JP2010064106A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus for efficiently performing laser beam machining correspondingly to a meandering machining position of a workpiece. <P>SOLUTION: The laser beam machining apparatus includes: a laser beam irradiation means including a laser beam oscillating means for oscillating a laser beam and a condenser 53 having a condensing lens 534 for converging a laser beam oscillated from the laser beam oscillating means; a condenser moving actuator 8 for moving the condenser in the Y axis direction; a condenser moving position detector for detecting the moving position of the condenser in the Y axis direction; a machining position displacement detector 7 for detecting displacement of the workpiece in the Y axis direction, in the machining position in front of the machining direction from the optical axis of the laser beam converged by the condensing lens; and a controller for controlling the condenser moving actuator 8 on the basis of a detection signal from the machining position displacement detector 7 and the condenser moving position detector. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that performs laser processing by irradiating a workpiece with a laser beam, and more specifically, a wafer having a device formed in a plurality of regions partitioned by a street formed in a lattice shape on the surface. The present invention relates to a laser processing apparatus suitable for cutting an die bonding adhesive film mounted on the back surface of each device.

  For example, in a semiconductor device manufacturing process, devices such as IC and LSI are formed in a plurality of regions partitioned by streets (division lines) formed in a lattice shape on the surface of a semiconductor wafer having a substantially disk shape, Individual devices are manufactured by dividing each region in which the devices are formed along a street. As a dividing device for dividing a semiconductor wafer, a cutting device called a dicing device is generally used. This cutting device cuts a semiconductor wafer along a street with a cutting blade having a thickness of several tens of micrometers. Devices divided in this way are packaged and widely used in electric devices such as mobile phones and personal computers.

Each of the divided devices has a die bonding adhesive film called a die attach film having a thickness of 20 to 40 μm formed of an epoxy resin or the like on the back surface thereof, and a die that supports the device through the adhesive film. Bonding is performed by heating the bonding frame. As a method of attaching an adhesive film for die bonding to the back surface of the device, the adhesive film is attached to the back surface of the semiconductor wafer, the semiconductor wafer is attached to the dicing tape through this adhesive film, and then the surface of the semiconductor wafer By cutting the adhesive film together with the semiconductor wafer with a cutting blade along the street formed in the above, a device having the adhesive film mounted on the back surface is formed. (For example, refer to Patent Document 1.)
JP 2000-182959 A

  In recent years, electric devices such as mobile phones and personal computers are required to be lighter and smaller, and thinner devices are required. As a technique for dividing a device thinner, a so-called dicing method called a dicing method has been put into practical use. In this tip dicing method, a dividing groove having a predetermined depth (a depth corresponding to the finished thickness of the device) is formed along the street from the surface of the semiconductor wafer, and then the semiconductor wafer having the dividing groove formed on the surface is formed. This is a technique in which the back surface is ground and a dividing groove is exposed on the back surface to divide the device into individual devices, which can be processed to a thickness of 50 μm or less.

  However, when the semiconductor wafer is divided into individual devices by the tip dicing method, after forming a dividing groove having a predetermined depth along the street from the surface of the semiconductor wafer, the back surface of the semiconductor wafer is ground to the back surface. Since the dividing groove is exposed, the adhesive film for die bonding cannot be mounted on the back surface of the semiconductor wafer in advance. Therefore, when bonding a device manufactured by the previous dicing method to the die bonding frame, the bonding agent must be inserted between the device and the die bonding frame, and the bonding operation should be performed smoothly. There is a problem that can not be.

In order to solve such problems, an adhesive film for die bonding is attached to the back surface of the semiconductor wafer divided into individual devices by the pre-dicing method, and the semiconductor wafer is attached to the dicing tape through this adhesive film. After that, the portion of the adhesive film exposed along the gap between the devices is irradiated with a laser beam from the surface side of the device through the gap, so that the portion of the adhesive film exposed in the gap is fused. A device manufacturing method has been proposed. (For example, see Patent Document 2.)
JP 2002-118081 A

  However, the divided grooves of the semiconductor wafer divided into individual devices by the above-described dicing method in which the rear surface of the semiconductor wafer is ground to expose the divided grooves are meandering. For this reason, it is difficult to irradiate the adhesive film mounted on the back surface of the semiconductor wafer meandering with the dividing grooves along the dividing grooves. Therefore, the semiconductor device manufacturing method disclosed in Patent Document 2 has a problem in that the surface of the device is irradiated with a laser beam to damage the device.

In order to solve such a problem, before irradiating the laser beam along the dividing groove to the adhesive film mounted on the back surface of the semiconductor wafer divided into individual devices by the dicing method, the meandering state of the dividing groove is changed. There has been proposed a laser processing method for detecting and storing in a storage means and irradiating the adhesive film with a laser beam along the dividing groove based on the meandering information. (For example, refer to Patent Document 3.)
JP 2006-278684 A

  Thus, although the technique disclosed in Patent Document 3 can irradiate a laser beam along the meandering divided grooves, it is necessary to perform a detection process for detecting the meandering state of all the divided grooves. For this reason, it is not always satisfactory in terms of productivity.

  The present invention has been made in view of the above facts, and a main technical problem thereof is to provide a laser processing apparatus capable of efficiently performing laser processing corresponding to a meandering processing position of a workpiece. .

In order to solve the main technical problem, according to the present invention, a chuck table for holding a workpiece, laser beam irradiation means for irradiating a workpiece held on the chuck table with a laser beam, the chuck table, Processing feed means for relatively moving the laser beam irradiation means in the processing feed direction (X-axis direction); Index feed direction (Y-axis) orthogonal to the chuck table and the laser beam irradiation means in the processing feed direction (X-axis direction) In a laser processing apparatus comprising indexing feeding means that can move relative to (direction),
The laser beam irradiating unit includes a laser beam oscillating unit that oscillates a laser beam, and a condenser including a condensing lens that condenses the laser beam oscillated from the laser beam oscillating unit.
A condenser moving actuator for moving the condenser in the Y-axis direction;
A collector moving position detecting means for detecting a moving position of the collector in the Y-axis direction;
Machining position displacement detection means for detecting the displacement of the workpiece in the Y axis direction at the machining position ahead of the machining direction from the optical axis of the laser beam collected by the condenser lens;
Control means for controlling the condenser movement actuator based on detection signals from the processing position displacement detection means and the condenser movement position detection means,
A laser processing apparatus is provided.

The machining position displacement detection means detects the displacement of the workpiece in the Y-axis direction at the machining position through the condenser lens.
The condenser includes a dichroic mirror that guides the laser beam oscillated from the laser beam oscillation means to the condenser lens, and the machining position displacement detection means passes through the dichroic mirror and the condenser lens in the Y-axis direction at the machining position. Detect the displacement of the workpiece.
The processing position displacement detection means is preferably disposed on both sides in the processing direction with respect to the optical axis of the laser beam condensed by the condenser lens.

  The laser processing apparatus according to the present invention is configured as described above, and controls the condenser moving actuator in accordance with the amount of deviation in the Y-axis direction of the processing position detected by the processing position displacement detection means. Even if the processing position is meandering, laser processing can be efficiently performed corresponding to the meandering processing position.

  Preferred embodiments of a wafer laser processing method and a laser processing apparatus according to the present invention will be described below 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. A laser processing apparatus shown in FIG. 1 includes a stationary base 2 and a chuck table mechanism 3 that is disposed on the stationary base 2 so as to be movable in a machining feed direction (X-axis direction) indicated by an arrow X and holds a workpiece. A laser beam irradiation unit support mechanism 4 disposed on the stationary base 2 so as to be movable in an index feed direction (Y-axis direction) indicated by an arrow Y perpendicular to the direction indicated by the arrow X, and the laser beam unit support mechanism 4 And a laser beam irradiation unit 5 disposed so as to be movable in the direction indicated by the arrow Z.

  The chuck table mechanism 3 includes a pair of guide rails 31, 31 arranged on the stationary base 2 in parallel along the machining feed direction (X-axis direction) indicated by an arrow X, and the guide rails 31, 31. The first sliding block 32 is movably arranged in the processing feed direction indicated by the arrow X, and is movably arranged on the first sliding block 32 in the index feed direction (Y-axis direction) indicated by the arrow Y. A second slide block 33 is provided, a support table 35 supported by a cylindrical member 34 on the second slide block 33, and a chuck table 36 as a workpiece holding means. The chuck table 36 includes a suction chuck 361 formed of a porous material, and holds, for example, a disk-shaped wafer, which is a workpiece, on a holding surface which is the upper surface of the suction chuck 361 by suction means (not shown). It is like that. The chuck table 36 configured as described above is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. The chuck table 36 is provided with a clamp 362 for fixing an annular frame described later.

  The first sliding block 32 is provided with a pair of guided grooves 321 and 321 fitted to the pair of guide rails 31 and 31 on the lower surface thereof, and in the index feed direction indicated by an arrow Y on the upper surface thereof. A pair of guide rails 322 and 322 formed in parallel with each other are provided. The first sliding block 32 configured in this way is processed by the arrow X along the pair of guide rails 31, 31 when the guided grooves 321, 321 are fitted into the pair of guide rails 31, 31. It is configured to be movable in the feed direction. The chuck table mechanism 3 in the illustrated embodiment includes a machining feed means 37 for moving the first sliding block 32 along the pair of guide rails 31 and 31 in the machining feed direction indicated by the arrow X. The processing feed means 37 includes a male screw rod 371 disposed in parallel between the pair of guide rails 31 and 31, and a drive source such as a pulse motor 372 for rotationally driving the male screw rod 371. One end of the male screw rod 371 is rotatably supported by a bearing block 373 fixed to the stationary base 2, and the other end is connected to the output shaft of the pulse motor 372 by transmission. The male screw rod 371 is screwed into a penetrating female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the first sliding block 32. Accordingly, by driving the male screw rod 371 in the forward and reverse directions by the pulse motor 372, the first slide block 32 is moved along the guide rails 31 and 31 in the machining feed direction (X-axis direction) indicated by the arrow X. .

  The second sliding block 33 is provided with a pair of guided grooves 331 and 331 which are fitted to a pair of guide rails 322 and 322 provided on the upper surface of the first sliding block 32 on the lower surface thereof. By fitting the guided grooves 331 and 331 to the pair of guide rails 322 and 322, the guided grooves 331 and 331 are configured to be movable in the indexing feed direction indicated by the arrow Y (Y-axis direction). The chuck table mechanism 3 in the illustrated embodiment includes an index feed direction (Y-axis direction) indicated by an arrow Y along the pair of guide rails 322 and 322 provided on the first slide block 32. The first index feeding means 38 for moving to the first position is provided. The first index feed means 38 includes a male screw rod 381 disposed in parallel between the pair of guide rails 322 and 322, and a drive source such as a pulse motor 382 for rotationally driving the male screw rod 381. It is out. One end of the male screw rod 381 is rotatably supported by a bearing block 383 fixed to the upper surface of the first sliding block 32, and the other end is connected to the output shaft of the pulse motor 382. The male screw rod 381 is screwed into a penetrating female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the second sliding block 33. Therefore, by driving the male screw rod 381 forward and backward by the pulse motor 382, the second slide block 33 is moved along the guide rails 322 and 322 in the indexing feed direction (Y-axis direction) indicated by the arrow Y. .

  The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41, 41 arranged in parallel along the indexing feed direction indicated by the arrow Y on the stationary base 2, and the arrow Y on the guide rails 41, 41. The movable support base 42 is provided so as to be movable in the direction indicated by (Y-axis direction). The movable support base 42 includes a movement support portion 421 that is movably disposed on the guide rails 41, 41, and a mounting portion 422 that is attached to the movement support portion 421. The mounting portion 422 is provided with a pair of guide rails 423 and 423 extending in the direction indicated by the arrow Z on one side surface in parallel. The laser beam irradiation unit support mechanism 4 in the illustrated embodiment has a second index for moving the movable support base 42 along the pair of guide rails 41 and 41 in the index feed direction (Y-axis direction) indicated by the arrow Y. A feeding means 43 is provided. The second index feed means 43 includes a male screw rod 431 disposed in parallel between the pair of guide rails 41, 41, and a drive source such as a pulse motor 432 for rotationally driving the male screw rod 431. It is out. One end of the male screw rod 431 is rotatably supported by a bearing block (not shown) fixed to the stationary base 2, and the other end is connected to the output shaft of the pulse motor 432. The male screw rod 431 is screwed into a female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the moving support portion 421 constituting the movable support base 42. Therefore, the movable support base 42 is moved along the guide rails 41 and 41 in the indexing feed direction (Y-axis direction) indicated by the arrow Y by driving the male screw rod 431 forward and backward by the pulse motor 432. .

  The laser beam irradiation unit 5 in the illustrated embodiment includes a unit holder 51 and laser beam irradiation means 52 attached to the unit holder 51. The unit holder 51 is provided with a pair of guided grooves 511 and 511 that are slidably fitted to a pair of guide rails 423 and 423 provided in the mounting portion 422. By being fitted to the guide rails 423 and 423, the guide rails 423 and 423 are supported so as to be movable in the direction indicated by the arrow Z (Z-axis direction).

  The illustrated laser beam irradiation means 52 includes a cylindrical casing 521 that is fixed to the unit holder 51 and extends substantially horizontally. Further, as shown in FIG. 2, the laser beam irradiation unit 52 adjusts the output of the pulse laser beam oscillated by the pulse laser beam oscillation unit 522 that oscillates the pulse laser beam LB disposed in the casing 521 and the pulse laser beam oscillation unit 522. Output adjusting means 523, and a condenser 53 that is disposed at the tip of the casing 521 and irradiates the workpiece held by the chuck table 36 with a pulse laser beam oscillated by the pulse laser beam oscillation means 522. . The pulse laser beam oscillation means 522 is composed of a pulse laser beam oscillator 522a composed of a YAG laser oscillator or a YVO4 laser oscillator, and a repetition frequency setting means 522b attached thereto.

The condenser 53 will be described with reference to FIGS.
The condenser 53 shown in FIGS. 3 to 5 includes a condenser housing 531, and the condenser housing 531 is attached to the tip of the casing 521 constituting the laser beam irradiation means 52 as shown in FIG. 3. The two support rods 6 and 6 are mounted so as to be movable in the Y-axis direction. That is, through holes 531a and 531a are provided on both sides of the collector housing 531, respectively. By inserting these through holes 531a and 531a into the two support rods 6 and 6, the collector housing is provided. 531 is slidably supported on the two support rods 6 and 6. An opening 531b is formed in the upper wall of the concentrator housing 531, and a transparent glass plate 532 is attached to the opening 531b. In the concentrator housing 531, as shown in FIG. 4, a dichroic mirror 533 that redirects the pulse laser beam LB oscillated from the pulse laser beam oscillation means 522 downward, and directed downward by the dichroic mirror 533. A condensing lens 534 for condensing the direction-converted pulsed laser beam LB and irradiating the workpiece W held on the chuck table 36 is provided. In the condenser housing 531, a band pass filter 535 and an imaging lens 536 are disposed above the dichroic mirror 533.

  On the upper side of the condenser 53 described above, a machining position displacement detection that detects the displacement of the workpiece in the Y-axis direction at the machining position ahead of the machining direction from the optical axis of the pulsed laser beam LB condensed by the condenser lens 534. Means 7 are provided. As shown in FIG. 5, the processing position displacement detection means 7 is composed of two line image sensors 7a and 7b in the illustrated embodiment, and is disposed at intervals in the processing feed direction (X-axis direction). ing. The one line image sensor 7a passes through the imaging lens 536, the band pass filter 535, the dichroic mirror 533, and the condenser lens 534, for example, 3 mm right in FIG. The machining position P1 is detected. Further, the other line image sensor 7b has an imaging lens 536, a band pass filter 535, a dichroic mirror 533, and a condenser lens 534 through the optical axis of the pulse laser beam LB collected by the condenser lens 534 in FIG. The left processing position P2 is detected. The line image sensors 7a and 7b detect a deviation in the Y-axis direction of a division groove which is a processing region described later. As the processing position detection means 7, a position detection element (PSD) may be used.

  The laser beam irradiation unit 5 in the illustrated embodiment includes a condenser moving actuator 8 that moves the condenser 53 in the Y-axis direction. The concentrator moving actuator 8 is a voice coil motor in the illustrated embodiment. As shown in FIG. 4, the concentrator moving actuator 8 composed of a voice coil motor includes a columnar movable rod 81 connected to the concentrator housing 531 and a permanent rod disposed on the outer peripheral surface of the movable rod 81. A magnet 82, a cup-shaped coil support member 83 fixed to the two support rods 6, 6, and a coil 84 disposed so as to surround the permanent magnet 82 on the inner peripheral surface of the coil support member 83. And is composed of. As shown in FIG. 3, the coil support member 83 has through holes 831 and 831 on both sides, and the through holes 831 and 831 are fitted into the two support rods 6 and 6. Then, one end face of the coil support member 83 (end face on the collector housing 531 side) is brought into contact with stoppers 61, 61 provided on the two support rods 6, 6, and the tip ends of the two support rods 6, 6. The coil support member 83 is fixed to the two support rods 6 and 6 by screwing the fastening nuts 85 into the male screws 62 and 62 formed in FIG. The condenser moving actuator 8 composed of the voice coil motor configured as described above generates a thrust in the moving rod 81 provided with the permanent magnet 82 in accordance with Fleming's left-hand rule when a current is passed through the coil 84. That is, for example, when a current is applied to the coil 84 from one direction, a thrust is generated in the moving rod 81 provided with the permanent magnet 82 in the right direction in FIG. For example, a thrust is generated on the moving rod 81 provided with the magnet 82 to the left in FIG. Therefore, the collector housing 531 to which the movable rod 81 is connected is moved rightward or leftward in FIG. 4 depending on the direction of the current applied to the coil 84.

  Continuing the description with reference to FIG. 3, the laser beam irradiation unit 5 in the illustrated embodiment includes a collector moving position detecting means 9 for detecting the Y-axis direction moving position of the collector 53. The collector moving position detecting means 9 includes a linear scale 91 disposed on the side surface of the collector housing 531 and a read head 92 attached to a casing 521 constituting the laser beam irradiation means 52. In the illustrated embodiment, the reading head 92 of the condenser moving position detecting means 9 sends a pulse signal of one pulse every 1 μm to the control means described later.

  Returning to FIG. 1, the description will be continued. At the front end of the casing 521 constituting the laser beam irradiation means 52, an imaging means 11 for detecting a processing region to be laser processed by the laser beam irradiation means 52 is disposed. . In the illustrated embodiment, the imaging unit 11 includes, in addition to a normal imaging device (CCD) that captures an image with visible light, an infrared illumination unit that irradiates a workpiece with infrared rays, and an infrared ray that is irradiated by the infrared illumination units. And an imaging device (infrared CCD) that outputs an electrical signal corresponding to the infrared rays captured by the optical system, and sends the captured image signal to a control means (not shown).

  The laser beam irradiation unit 5 in the illustrated embodiment includes a moving means 54 for moving the unit holder 51 along the pair of guide rails 423 and 423 in the direction indicated by the arrow Z. The moving means 54 includes a male screw rod (not shown) disposed between the pair of guide rails 423 and 423, and a driving source such as a pulse motor 542 for rotationally driving the male screw rod. By driving the male screw rod (not shown) by the motor 542 in the forward and reverse directions, the unit holder 51 and the laser beam irradiation means 52 are moved along the guide rails 423 and 423 in the direction indicated by the arrow Z. In the illustrated embodiment, the laser beam irradiation means 52 is moved upward by driving the pulse motor 542 in the forward direction, and the laser beam irradiation means 52 is moved downward by driving the pulse motor 542 in the reverse direction. Yes.

  The laser processing apparatus in the illustrated embodiment includes the control means 12 shown in FIG. The control means 12 is composed of a computer, and a central processing unit (CPU) 121 that performs arithmetic processing according to a control program, a read-only memory (ROM) 122 that stores a control program, and a readable / writable data that stores arithmetic results. A random access memory (RAM) 123, an input interface 124 and an output interface 125 are provided. Detection signals from the line image sensors 7a and 7b, the condenser moving position detection means 9, the imaging means 11 and the like are input to the input interface 124 of the control means 12. The output interface 125 of the control means 12 includes the pulse motor 372, the pulse motor 382, the pulse motor 432, the pulse motor 542, the pulse laser beam oscillation means 522 of the laser beam irradiation means 52, the output adjustment means 523, and a voice coil motor. A control signal is output to the coil 84 and the like of the condenser moving actuator 8.

The laser processing apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
Here, a semiconductor wafer as a wafer to be processed by the laser processing apparatus will be described with reference to FIG. The semiconductor wafer 10 shown in FIG. 7 is made of, for example, a silicon wafer having a thickness of 600 μm, and a plurality of streets 101 are formed in a lattice shape on the surface 10a. On the surface 10a of the semiconductor wafer 10, devices 102 such as IC and LSI are formed in a plurality of regions partitioned by a plurality of streets 101 formed in a lattice shape. A procedure for dividing the semiconductor wafer 10 into individual semiconductor devices by the prior dicing method will be described.

  In order to divide the semiconductor wafer 10 into individual semiconductor devices by the tip dicing method, first, the semiconductor wafer 10 is cut along the street 101 with a cutting blade from the surface 10a side of the semiconductor wafer 10, and has a depth corresponding to the finished thickness of the device 102. A split groove forming step for forming the split grooves is performed. This dividing groove forming step is performed using a cutting device 13 shown in FIG. The cutting device 13 shown in FIG. 8A is held by the chuck table 131 that holds the workpiece, the cutting means 132 that cuts the workpiece held on the chuck table 131, and the chuck table 131. An image pickup means 133 for picking up an image of the workpiece is provided. The chuck table 131 is configured to suck and hold a workpiece. The chuck table 131 is moved in a cutting feed direction indicated by an arrow X in FIG. 8 by a cutting feed means (not shown) and is indicated by an arrow Y by an index feed means (not shown). It can be moved in the index feed direction shown.

  The cutting means 132 includes a spindle housing 134 disposed substantially horizontally, a rotary spindle 135 rotatably supported on the spindle housing 134, and a cutting blade 136 attached to the tip of the rotary spindle 135. The rotating spindle 135 is rotated in the direction indicated by the arrow 135a by a servo motor (not shown) disposed in the spindle housing 134. The imaging means 133 is attached to the tip of the spindle housing 134, and illuminates the work piece, an optical system that captures an area illuminated by the illumination means, and an image captured by the optical system. An image pickup device (CCD) or the like for picking up images is provided, and the picked up image signal is sent to a control means (not shown).

  In order to perform the division groove forming process using the cutting device 13 described above, the back surface 10b side of the semiconductor wafer 10 is placed on the chuck table 131 as shown in FIG. By operating, the semiconductor wafer 10 is held on the chuck table 131. Therefore, the surface 10a of the semiconductor wafer 10 held on the chuck table 131 is on the upper side. In this manner, the chuck table 131 that sucks and holds the semiconductor wafer 10 is positioned directly below the imaging unit 133 by a cutting feed unit (not shown).

  When the chuck table 131 is positioned immediately below the image pickup means 133, an alignment operation for detecting a cutting region in which the division grooves are to be formed along the street 101 of the semiconductor wafer 10 is executed by the image pickup means 133 and a control means (not shown). That is, the imaging unit 133 and a control unit (not shown) perform image processing such as pattern matching for aligning the street 101 formed in a predetermined direction of the semiconductor wafer 10 and the cutting blade 136, and cutting region Alignment is performed (alignment process). Further, the alignment of the cutting region is similarly performed on the street 101 formed in the semiconductor wafer 10 and extending in a direction orthogonal to the predetermined direction.

  When the alignment for detecting the cutting area of the semiconductor wafer 10 held on the chuck table 131 is performed as described above, the chuck table 131 holding the semiconductor wafer 10 is moved to the cutting start position of the cutting area. . Then, the cutting blade 136 is moved downward while rotating in the direction indicated by the arrow 135a in FIG. In this cutting feed position, the outer peripheral edge of the cutting blade 136 is set to a depth position (for example, 50 μm) corresponding to the finished thickness of the device from the surface of the semiconductor wafer 10. When the cutting blade 136 is cut and fed in this way, the chuck table 131 is cut and fed in the direction indicated by the arrow X in FIG. As shown in FIG. 4B, a dividing groove 110 having a depth (for example, 50 μm) corresponding to the finished thickness of the device is formed along the street 101 (dividing groove forming step).

  9A and 9B are formed after the above-described dividing groove forming step is performed to form the dividing groove 110 having a depth corresponding to the finished thickness of the device along the street 101 on the surface 10a of the semiconductor wafer 10. ), A protective tape 14 for grinding that protects the device 102 is attached to the surface 10a (surface on which the device 102 is formed) of the semiconductor wafer 10 (protective tape attaching step). The protective tape 14 is a polyolefin sheet having a thickness of 150 μm in the illustrated embodiment.

  Next, a wafer dividing step is performed in which the back surface 10b of the semiconductor wafer 10 having the protective tape 14 attached to the front surface is ground, and the dividing grooves 110 are exposed on the back surface 10b and divided into individual devices. This wafer dividing step is performed using a grinding apparatus 15 shown in FIG. A grinding apparatus 15 shown in FIG. 10A includes a grinding table 153 having a chuck table 151 for holding a workpiece and a grinding wheel 152 for grinding the workpiece held on the chuck table 151. It has. In order to perform the wafer dividing step using the grinding device 15, the protective tape 14 side of the semiconductor wafer 10 is placed on the chuck table 151, and the suction means (not shown) is operated to bring the semiconductor wafer 10 into the chuck table. 151 on. Accordingly, the back surface 10b of the semiconductor wafer 10 held on the chuck table 151 is on the upper side. When the semiconductor wafer 10 is held on the chuck table 151 in this way, the grinding wheel 152 of the grinding means 153 is moved in the direction indicated by the arrow 152a while the chuck table 151 is rotated in the direction indicated by the arrow 151a, for example, at 300 rpm. For example, while rotating at 6000 rpm, the back surface 10b of the semiconductor wafer 10 is brought into contact with the surface of the semiconductor wafer 10 to be ground, and the divided grooves 110 are ground until the dividing grooves 110 appear on the back surface 10b as shown in FIG. By grinding until the dividing grooves 110 are exposed in this way, the semiconductor wafer 10 is divided into individual devices 102 as shown in FIG. In addition, since the protective tape 14 is stuck on the surface of the plurality of divided devices 102, the form of the semiconductor wafer 10 is maintained without being separated.

  If the semiconductor wafer 10 is divided into individual devices 102 by performing the wafer dividing step by the above-described dicing method, an adhesive film for die bonding is applied to the back surface 10b of the semiconductor wafer 10 divided into the individual devices 102. The adhesive film mounting process to mount is implemented. That is, as shown in FIGS. 11A and 11B, the adhesive film 16 is attached to the back surface 10 b of the semiconductor wafer 10 divided into individual devices 102. At this time, as described above, the adhesive film 16 is pressed and adhered to the back surface 10b of the semiconductor wafer 10 while being heated at a temperature of 80 to 200 ° C.

  If the adhesive film dividing step described above is performed, the adhesive film 16 side of the semiconductor wafer 10 is attached to the surface of the dicing tape attached to the annular frame, and the protection attached to the surface of the semiconductor wafer 10. A wafer support process for peeling the tape 14 is performed. That is, as shown in FIG. 12, the adhesive film 16 side of the semiconductor wafer 10 on which the adhesive film dividing step has been performed is attached to the surface of the dicing tape 18 mounted on the annular frame 17. Then, the protective tape 14 attached to the surface of the semiconductor wafer 10 is peeled off.

Next, an adhesive film cutting process is performed in which the adhesive film 16 mounted on the back surface of the semiconductor wafer 10 is irradiated with a laser beam along the divided grooves 110 to cut the adhesive film 16 along the divided grooves 110. This adhesive film dividing step is performed using the laser processing apparatus shown in FIGS.
In order to perform the adhesive film cutting step, the semiconductor wafer 10 supported on the annular frame 17 via the dicing tape 18 as shown in FIG. 12 is placed on the chuck table 36 of the laser processing apparatus shown in FIG. Place the side. Then, by operating a suction means (not shown), the semiconductor wafer 10 is sucked and held on the chuck table 36 via the dicing tape 18. The annular frame 17 is fixed by a clamp 362.

  As described above, the chuck table 36 that sucks and holds the semiconductor wafer 10 is positioned immediately below the imaging unit 11 by the processing feed unit 37. When the chuck table 36 is positioned immediately below the image pickup means 11, the image pickup means 11 and the control means 12 execute an alignment operation for detecting a processing region to be laser processed of the adhesive film 16 mounted on the back surface of the semiconductor wafer 10. That is, the imaging unit 11 and the control unit 12 perform image processing such as pattern matching for aligning the dividing grooves 110 formed in a predetermined direction of the semiconductor wafer 10 and the condenser 11 to perform alignment. Carry out. In addition, alignment is similarly performed on the street 101 formed in the direction orthogonal to the predetermined direction formed in the semiconductor wafer 10.

  The dividing groove 110 formed on the surface side of the semiconductor wafer 10 in the dividing groove forming step shown in FIG. 8 is accurately formed along the street 101. In the wafer dividing step shown in FIG. When the back surface of the semiconductor wafer 10 is ground to divide the semiconductor wafer 10 into the individual devices 102, the devices 102 are displaced as shown in FIG. The deviation of the device 102 may be about 100 μm at maximum. Therefore, when the laser beam is irradiated linearly, the surface of the device 102 is irradiated with the laser beam and the device 102 is damaged. In order to solve this problem, the laser processing apparatus in the illustrated embodiment performs the adhesive film cutting step as follows.

  When the alignment of the laser beam irradiation position is performed as described above, the chuck table 36 is moved to the laser beam irradiation region where the condenser 53 of the laser beam irradiation means 52 is located, and as shown in FIG. One end of the dividing groove 110 (left end in FIG. 14A) is positioned directly below the condenser 53 of the laser beam irradiation means 52. Then, the control means 12 operates the one line image sensor 7a to process the processing position forward in the processing direction (rightward in FIG. 14A) from the optical axis of the pulsed laser beam LB emitted from the condenser 53. Detect P1. The line image sensor 7 a detects a shift in the Y-axis direction of the dividing groove 110 and sends a detection signal to the control means 12. Next, the control means 12 operates the machining feed means 37 to move the chuck table 36 in the direction indicated by the arrow X1 in FIG. 14A at a predetermined feed speed, as shown in FIG. 14B. When the irradiation position of the pulsed laser beam LB irradiated from the condenser 53 reaches one end of the dividing groove 110 (the left end in FIG. 14A), the laser beam irradiation means 52 is operated to remove the adhesive film from the condenser 53. 16 is irradiated with a laser beam LB having an absorptive wavelength, and the other end of the dividing groove 110 (the right end in FIG. 14B) is the irradiation position of the condenser 53 as shown in FIG. Is reached, the operation of the laser beam irradiation means 52 is stopped and the operation of the processing feed means 37 is stopped (first adhesive film cutting step). At this time, the pulse laser beam LB irradiated from the condenser 53 of the laser beam irradiation means 52 is irradiated through the dividing groove 110 with the focal point P aligned with the upper surface of the adhesive film 16.

  In the first adhesive film dividing step, the processing position P1 ahead of the processing direction is detected from the optical axis of the pulsed laser beam LB irradiated from the condenser 53 by the line image sensor 7a, and control is performed based on this detection signal. The means 12 obtains the deviation of the dividing groove 110 in the Y-axis direction, and controls the current applied to the coil 84 of the condenser moving actuator 8 composed of a voice coil motor corresponding to the deviation amount of the dividing groove 110 in the Y-axis direction. Then, the condenser 53 is moved in the Y-axis direction. On the other hand, the control means 12 inputs the position information of the condenser 53 from the read head 92 of the condenser movement position detecting means 9, and the condenser 53 corresponds to the amount of deviation of the dividing groove 110 in the Y-axis direction. When the measured position is reached, the operation of the condenser moving actuator 8 is stopped. In other words, in the illustrated embodiment, the condenser moving actuator 8 positions the condenser 53 at a position corresponding to the amount of deviation when the chuck table 36 is processed by 3 mm from the time of detection by the line image sensor 7a. Thus, by controlling the condenser moving actuator 8 formed of a voice coil motor in accordance with the amount of deviation in the Y-axis direction of the dividing groove 110 detected by the line image sensor 7a, (a) and (a) in FIG. As shown in b), the adhesive film 16 has a cut groove 160 which is melted and evaporated along the meandering divided groove 110. In the first adhesive film dividing step described above, the line image sensor 7a that detects the processing position P1 ahead of the processing direction from the optical axis of the pulsed laser beam LB collected by the condensing lens 534 detects through the condensing lens 534. Therefore, the position close to the optical axis of the pulse laser beam LB condensed by the condenser lens 534 can be detected. Therefore, the moving stroke of the chuck table 36 in the first adhesive film dividing step does not become long.

In addition, the processing conditions in the said adhesive film division | segmentation process are set as follows, for example.
Laser beam type: Solid laser (YVO4 laser, YAG laser)
Wavelength: 355nm
Repetition frequency: 50 kHz
Average output: 0.5W
Condensing spot diameter: φ10μm
Processing feed rate: 500 mm / sec

  If the first adhesive film dividing step is performed, the chuck table 36 is divided from the state shown in FIG. 14C in the indexing feed direction (direction perpendicular to the paper surface in FIG. 14C). The index is sent out at intervals of 110. This state is the state shown in FIG. Then, the control means 12 operates the line image sensor 7b to set the processing position P2 ahead of the processing direction (leftward in FIG. 16A) from the optical axis of the pulse laser beam LB irradiated from the condenser 53. To detect. Next, the control means 12 operates the machining feed means 37 to move the chuck table 36 in the direction indicated by the arrow X2 in FIG. 16A at a predetermined feed speed, as shown in FIG. 16B. When the irradiation position of the pulsed laser beam LB irradiated from the condenser 53 reaches the other end of the dividing groove 110 (the right end in FIG. 16A), the laser beam irradiation means 52 is activated to bond from the condenser 53. The film 16 is irradiated with a laser beam LB having an absorptive wavelength, and one end of the dividing groove 110 (the left end in FIG. 16B) is the irradiation position of the condenser 53 as shown in FIG. Is reached, the operation of the laser beam irradiation means 52 is stopped and the operation of the processing feed means 37 is stopped (second adhesive film cutting step). As a result, similar to the first adhesive film dividing step, the adhesive film 16 has a meandering along the dividing groove 110 meandering corresponding to the amount of deviation of the dividing groove 110 in the Y-axis direction detected by the line image sensor 7a. A cutting groove is formed.

  When the first adhesive film dividing step and the second adhesive film dividing step described above are alternately performed and the adhesive film 16 is divided along all the dividing grooves 110 formed in a predetermined direction, the chuck table 36 is By rotating 90 degrees and alternately executing the first adhesive film dividing step and the second adhesive film dividing step along the dividing groove 110 formed in a direction orthogonal to the predetermined direction, The adhesive film 16 mounted on the back surface of the semiconductor wafer 10 is cut and divided for each device 102 divided by the dividing grooves 110. As described above, the laser processing apparatus according to the illustrated embodiment includes the two line image sensors 7a and 7b disposed as the processing position detection means 7 with an interval in the processing feed direction (X-axis direction). Therefore, when the first adhesive film dividing step is performed, one line image sensor 7a is activated, and when the second adhesive film dividing step is performed, the other line image sensor 7b is activated. Since the adhesive film dividing step can be performed when the chuck table 36 is reciprocated, the working efficiency can be improved.

The perspective view of the laser processing apparatus comprised according to this invention. The block diagram which shows simply the structure of the laser beam irradiation means with which the laser processing apparatus shown in FIG. 1 is equipped. The disassembled perspective view of the condensing device and the concentrator moving actuator which comprise the laser beam irradiation means shown in FIG. Sectional drawing of the collector shown in FIG. 3 and a collector moving actuator. AA line sectional view in FIG. The block diagram which shows the control means with which the laser processing apparatus shown in FIG. 1 is equipped. The perspective view of the semiconductor wafer as a to-be-processed object. Explanatory drawing of the division | segmentation groove | channel formation process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 7 along a street. Explanatory drawing of the protective tape sticking process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 7 along a street. Explanatory drawing of the wafer division | segmentation process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 7 along a street. Explanatory drawing of the adhesive film cutting process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 7 along a street. Explanatory drawing of the wafer support process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 7 along a street. FIG. 11 is an explanatory diagram showing a state of divided grooves formed in a semiconductor wafer divided into individual devices by the wafer dividing step shown in FIG. 10. Explanatory drawing of the 1st adhesive film cutting process implemented using the laser processing apparatus shown in FIG. Explanatory drawing which shows the processing state of an adhesive film in which an adhesive film cutting process is implemented using the laser processing apparatus shown in FIG. Explanatory drawing of the 2nd adhesive film cutting process implemented using the laser processing apparatus shown in FIG.

Explanation of symbols

2: Stationary base 3: Chuck table mechanism 31: Guide rail 36: Chuck table 37: Processing feed means 38: First index feed means
4: Laser beam irradiation unit support mechanism 41: Guide rail 42: Movable support base 43: Second index feed means
5: Laser beam irradiation unit 51: Unit holder 52: Laser beam processing means 522: Pulse laser beam oscillation means 53: Condenser 531: Condenser housing 533: Dichroic mirror 534: Condensing lens 535: Band pass filter 535
536: Imaging lens 7: Processing position displacement detection means 7a, 7b: Line image sensor 8: Concentrator movement actuator 9: Concentrator movement position detection means 10: Semiconductor wafer 11: Imaging means 12: Control means 13: Cutting device 14: protective tape 15: grinding device 16: adhesive film 17: annular frame 18: dicing tape

Claims (4)

A chuck table for holding a workpiece, a laser beam irradiation means for irradiating a workpiece held on the chuck table with a laser beam, and the chuck table and the laser beam irradiation means relative to the machining feed direction (X-axis direction) A machining feed means for moving the chuck table and the laser beam irradiation means relative to an index feed direction (Y-axis direction) perpendicular to the machining feed direction (X-axis direction). Laser processing equipment
The laser beam irradiating unit includes a laser beam oscillating unit that oscillates a laser beam, and a condenser including a condensing lens that condenses the laser beam oscillated from the laser beam oscillating unit.
A condenser moving actuator for moving the condenser in the Y-axis direction;
A collector moving position detecting means for detecting a moving position of the collector in the Y-axis direction;
Machining position displacement detection means for detecting the displacement of the workpiece in the Y axis direction at the machining position ahead of the machining direction from the optical axis of the laser beam collected by the condenser lens;
Control means for controlling the condenser movement actuator based on detection signals from the processing position displacement detection means and the condenser movement position detection means,
Laser processing equipment characterized by that.   The laser processing apparatus according to claim 1, wherein the processing position displacement detection means detects a displacement of the workpiece in the Y-axis direction at the processing position through the condenser lens.   The condenser includes a dichroic mirror that guides the laser beam oscillated from the laser beam oscillation means to the condenser lens, and the machining position displacement detection means passes through the dichroic mirror and the condenser lens in the Y-axis direction at the machining position. The laser processing apparatus according to claim 2, wherein a displacement of the workpiece is detected.   4. The laser processing apparatus according to claim 1, wherein the processing position displacement detection means is disposed on both sides in a processing direction with respect to an optical axis of a laser beam condensed by the condenser lens.

Images