JP2013031871A - Method for detecting displacement magnitude and laser processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting displacement magnitude which can accurately detect displacement magnitude between a light collector and an imaging means in a laser processor, and to provide the laser processor.SOLUTION: This method for detecting displacement magnitude detects the displacement magnitude between the light collector which condenses laser beams and irradiates an object to be processed held on a chuck table with the laser beam and the imaging means which images processed area of the object. The method includes a laser-beam engraving step of positioning the arbitrary detection site in the object directly beneath the light collector by operating a sending means, and engraving the arbitrary detection site in the object by emitting laser beams from the light collector by operating the laser beam irradiation means; and after performing the laser-beam engraving step, a displacement magnitude detecting step of moving the chuck table by a predetermined distance by operating the sending means so as to position directly beneath the imaging means, and determining displacement magnitude in the X-axis direction and Y-axis direction from the center of imaging area of the engraved mark formed on the object by the imaging means.

Description

  Disclosed is a displacement amount detection method for detecting a displacement amount between a condenser for condensing and irradiating a laser beam in a laser processing apparatus for performing laser processing on a workpiece such as a semiconductor wafer and an imaging means for imaging a processing region. And a laser processing apparatus.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines (scheduled processing lines) called streets arranged in a lattice pattern on the surface of a substantially disk-shaped semiconductor substrate, and ICs are formed in these partitioned regions. A device such as an LSI is formed. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual devices. In addition, optical device wafers in which light-receiving elements such as photodiodes and light-emitting elements such as laser diodes are stacked on the surface of the sapphire substrate are also divided into optical devices such as individual photodiodes and laser diodes by cutting along the streets. And widely used in electrical equipment.

  As a method of dividing the wafer such as the semiconductor wafer or the optical device wafer described above along the street, a laser processing groove is formed by irradiating a pulse laser beam along the street formed on the wafer, and along the laser processing groove. A method of breaking is proposed. (For example, refer to Patent Document 1.)

  In addition, as a method of dividing the wafer along the street, a pulse laser beam having a wavelength that is transparent to the wafer is irradiated along the street with a converging point aligned inside, and the wafer is broken along the street. A method of dividing the wafer along the street by applying an external force along the street where the altered layer as the starting point is formed continuously and the altered layer as the starting point of breakage is formed and the strength is reduced has been proposed. ing. (For example, see Patent Document 2.)

  As described above, a laser processing apparatus for performing laser processing on a wafer as a workpiece includes a chuck table having a workpiece holding surface for holding the workpiece, and a laser on the workpiece held on the chuck table. Laser beam irradiating means having a laser beam oscillating means for oscillating a laser beam for processing, and a condenser for condensing the laser beam oscillated by the laser beam oscillating means, the chuck table and the laser beam irradiating means in the processing feed direction (X Machining feed means for relatively moving in the axial direction), index feeding means for relatively moving the chuck table and the laser beam irradiation means in the index feeding direction (Y-axis direction) orthogonal to the X-axis direction, and machining feed X-axis direction position detecting means for detecting the X-axis direction moving position of the chuck table by means, And Y-direction position detecting means for detecting the Y-axis direction moving position of the chuck table by issuing feeding means, and a imaging means for imaging the processing region of the workpiece held on the chuck table. (For example, refer to Patent Document 3.)

JP 2006196664 A1 JP 2005-328441 A JP 2011-33383 A

In the laser processing apparatus described above, the condenser and the imaging means are disposed at a predetermined interval set on the same line in the processing feed direction (X-axis direction), and this positional relationship is accurately maintained. is important. However, the positional relationship between the condenser and the imaging means is shifted due to the thermal expansion or the like of the assembly parts constituting the laser processing apparatus. As a result, there is a problem that the spot of the laser beam emitted from the condenser cannot be positioned at the street position detected by the imaging means.
If processing is performed by positioning the spot of the laser beam irradiated from the condenser while being indexed and fed in the indexing direction (Y-axis direction) on the street, it forms a thermal expansion of the workpiece or a laser processing apparatus. Since the spot of the laser beam emitted from the collector is off the street due to the thermal expansion of the assembled parts, the processing of the wafer is interrupted halfway and the street line relative to the reference line formed in the imaging area of the imaging means Although misalignment is detected and the index feed amount in the Y-axis direction is corrected, it may not be corrected properly. In addition, the positional relationship between the condenser and the imaging means is shifted in the X-axis direction, and there is a problem that no correction can be made when there is a shift between the processing start point and the end point.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is a displacement amount detection method and laser processing capable of accurately detecting the displacement amount between a condenser and an imaging means in a laser processing apparatus. Is to provide a device.

In order to solve the main technical problem, according to the present invention, a chuck table having a workpiece holding surface for holding a workpiece, and a laser beam for laser processing the workpiece held on the chuck table. A laser beam irradiating unit having a laser beam oscillating unit that oscillates the laser beam and a condenser that condenses the laser beam oscillated by the laser beam oscillating unit; Processing feed means for moving the chuck table, index feed means for relatively moving the chuck table and the laser beam irradiation means in an index feed direction (Y-axis direction) orthogonal to the X-axis direction, and the chuck table by the work feed means X-axis direction position detecting means for detecting the X-axis direction moving position and the index feeding means Y-axis position detection means for detecting the movement position of the table in the Y-axis direction, and an image of the processing area of the workpiece that is arranged at a predetermined distance in the X-axis direction from the condenser and held on the chuck table A displacement amount detection method for detecting a displacement amount between the condenser and the imaging means in a laser processing apparatus comprising:
The processing feed means is operated to position an arbitrary detection portion of the workpiece held on the chuck table immediately below the light collector, and the laser beam irradiation means is operated to irradiate the laser beam from the light collector. A laser beam marking step for marking an arbitrary detection portion in the workpiece held by the chuck table;
After performing the laser beam marking step, the machining feed means is operated to move the chuck table by a predetermined distance so as to be positioned directly below the imaging means, and the marking formed on the workpiece held on the chuck table A displacement amount detecting step for obtaining a displacement amount in the X-axis direction and the Y-axis direction from the center of the imaging region of the imaging means,
A displacement amount detection method is provided.

Further, according to the present invention, a chuck table having a workpiece holding surface for holding a workpiece, and a laser beam oscillation means for oscillating a laser beam for laser processing the workpiece held on the chuck table; Laser beam irradiating means having a condenser for condensing the laser beam oscillated by the laser beam oscillating means, and machining feed means for relatively moving the chuck table and the laser beam irradiating means in the machining feed direction (X-axis direction) An index feed means for relatively moving the chuck table and the laser beam irradiation means in an index feed direction (Y-axis direction) perpendicular to the X-axis direction, and a position of the chuck table moved by the machining feed means in the X-axis direction. X-axis direction position detection means to detect, and the Y-axis direction movement position of the chuck table by the index feed means Y-axis direction position detecting means for detecting; imaging means for imaging a processing area of a workpiece that is disposed at a predetermined distance in the X-axis direction from the condenser and held on the chuck table; and the condenser A laser processing apparatus comprising: a control means including a memory for storing a displacement amount between the image pickup means and the imaging means;
The control means operates the processing feed means to position an arbitrary detection part in the workpiece held on the chuck table directly below the condenser, and operates the laser beam irradiation means to operate from the condenser. A laser beam marking step for marking an arbitrary detection portion in the workpiece held on the chuck table by irradiating a laser beam, and after performing the laser beam marking step, the processing feeding means is operated to operate the chuck table. Is moved by the predetermined distance and positioned immediately below the image pickup means, and the displacement in the X-axis direction and the Y-axis direction from the center of the image pickup area by the image pickup means of the mark formed on the workpiece held on the chuck table The displacement obtained by the displacement amount detection step is performed, and the displacement amount of the condenser and the imaging means stored in the memory is calculated. To update to,
A laser processing apparatus is provided.

  In the displacement amount detection method and laser processing apparatus according to the present invention, the processing feed means is operated to position an arbitrary detection portion in the workpiece held on the chuck table directly under the condenser, and the laser beam irradiation means is operated. By irradiating a laser beam from the condenser to mark an arbitrary detection part in the workpiece held on the chuck table, the machining feed means is operated to move the chuck table by a predetermined distance and immediately below the imaging means. The amount of displacement in the X-axis direction and Y-axis direction from the center of the imaging area by the imaging means of the positioning and marking formed on the workpiece held on the chuck table is obtained, so the machining positions detected by the imaging means are collected. Correct laser processing at the set processing position of the workpiece by correcting the amount of displacement when positioned directly below the optical device. Door can be.

  Further, the displacement amount detection method and laser processing apparatus according to the present invention include positioning and marking an arbitrary detection part in the workpiece held on the chuck table directly under the condenser, and then operating the processing feed means to check the chuck table. Is moved by a predetermined distance and positioned directly below the imaging means, and the displacement of the X-axis direction and the Y-axis direction from the center of the imaging area by the marking imaging means is determined. Even during laser processing, it can be easily performed, and the amount of displacement between the condenser and the imaging means can be updated, and the amount of movement of the chuck table can be adjusted based on the updated new amount of displacement. It can be corrected.

The perspective view of the laser processing apparatus comprised according to this invention. FIG. 2 is a block configuration diagram of laser beam irradiation means equipped in the laser processing apparatus shown in FIG. FIG. 2 is a block configuration diagram of control means equipped in the laser processing apparatus shown in FIG. The perspective view of the semiconductor wafer as a to-be-processed object. The perspective view which shows the state which affixed the semiconductor wafer shown in FIG. 4 on the surface of the protective tape with which the cyclic | annular flame | frame was mounted | worn. FIG. 2 is an explanatory diagram of a laser beam marking step in the displacement detection method according to the present invention that is performed in the laser processing apparatus shown in FIG. FIG. 2 is an explanatory diagram of a displacement amount detection step in the displacement amount detection method according to the present invention that is performed in the laser processing apparatus shown in FIG. FIG. 2 is an explanatory diagram of a laser processing groove forming step performed in the laser processing apparatus shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a displacement detection method and a laser processing apparatus 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. 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. And a laser beam irradiation unit 4 as a laser beam irradiation means disposed on the stationary base 2.

  The chuck table mechanism 3 includes a pair of guide rails 31 and 31 disposed in parallel along the X-axis direction on the stationary base 2, and is arranged on the guide rails 31 and 31 so as to be movable in the X-axis direction. A first sliding block 32 provided, a second sliding block 33 movably disposed on the first sliding block 32 in the Y-axis direction, and a cylindrical member on the second sliding 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 circular semiconductor wafer as a workpiece on a holding surface which is the upper surface of the suction chuck 361 by suction means (not shown). It is supposed to be. 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 that supports a workpiece such as a semiconductor wafer via a protective tape.

  The first sliding block 32 has a pair of guided grooves 321 and 321 fitted to the pair of guide rails 31 and 31 on the lower surface thereof, and is parallel to the upper surface along the Y-axis direction. A pair of formed guide rails 322 and 322 are provided. The first sliding block 32 configured in this manner moves in the X-axis direction along the pair of guide rails 31, 31 when the guided grooves 321, 321 are fitted into the pair of guide rails 31, 31. Configured to be possible. The chuck table mechanism 3 in the illustrated embodiment includes a processing feed means 37 for moving the first slide block 32 along the pair of guide rails 31, 31 in the X-axis direction. 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. Therefore, the first slide block 32 is moved in the X-axis direction along the guide rails 31 and 31 by driving the male screw rod 371 forward and backward by the pulse motor 372.

  The laser processing apparatus in the illustrated embodiment includes X-axis direction position detection means 374 for detecting the X-axis direction position of the chuck table 36. The X-axis direction position detecting means 374 is a linear scale 374a disposed along the guide rail 31, and a reading that is disposed along the linear scale 374a together with the first sliding block 32 disposed along the first sliding block 32. It consists of a head 374b. In the illustrated embodiment, the reading head 374b of the X-axis direction position detecting means 374 sends a pulse signal of one pulse every 1 μm to the control means described later. The control means described later detects the position of the chuck table 36 in the X-axis direction by counting the input pulse signals. When a pulse motor 372 is used as a drive source for the machining feed means 37, the drive pulse of a control means, which will be described later, that outputs a drive signal to the pulse motor 372 is counted, so that the X direction of the chuck table 36 The position can also be detected. When a servo motor is used as a drive source for the machining feed means 37, a pulse signal output from a rotary encoder that detects the rotation speed of the servo motor is sent to a control means described later, and the pulse signal input by the control means. Can be detected to detect the position of the chuck table 36 in the X-axis direction.

  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 Y-axis direction. The chuck table mechanism 3 in the illustrated embodiment includes an index feeding means 38 for moving the second sliding block 33 in the Y-axis direction along a pair of guide rails 322 and 322 provided on the first sliding block 32. It has. The index feeding 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. 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 Y-axis direction.

  The laser processing apparatus in the illustrated embodiment includes Y-axis direction position detecting means 384 for detecting the Y-axis direction position of the second sliding block 33. The Y-axis direction position detecting means 384 is a linear scale 384a disposed along the guide rail 322, and a reading which is disposed along the linear scale 384a together with the second sliding block 33 disposed along the second sliding block 33. And a head 384b. In the illustrated embodiment, the reading head 384b of the Y-axis direction position detecting means 384 sends a pulse signal of one pulse every 1 μm to the control means described later. The control means described later detects the position of the chuck table 36 in the Y-axis direction by counting the input pulse signals. When the pulse motor 382 is used as the drive source of the index feed means 38, the drive pulse of the control means, which will be described later, that outputs a drive signal to the pulse motor 382 is counted, so that the chuck table 36 is moved in the Y-axis direction. The position can also be detected. Further, when a servo motor is used as the drive source of the index feed means 38, a pulse signal output from a rotary encoder that detects the rotation speed of the servo motor is sent to the control means described later, and the pulse signal input by the control means Can be detected to detect the position of the chuck table 36 in the Y-axis direction.

  The laser beam irradiation unit 4 includes a support member 41 disposed on the stationary base 2, a casing 42 supported by the support member 41 and extending substantially horizontally, and a laser beam disposed on the casing 42. Irradiation means 5 and imaging means 6 for detecting a processing region to be laser processed are provided. As shown in FIG. 2, the laser beam irradiation means 5 condenses the pulse laser beam oscillation means 51 and the workpiece W held on the chuck table 36 by condensing the pulse laser beam oscillated from the pulse laser beam oscillation means 51. A condenser 52 is provided. The pulse laser beam oscillation means 51 is composed of a pulse laser beam oscillator 511 composed of a YAG laser oscillator or a YVO4 laser oscillator, and a repetition frequency setting means 512 attached thereto. The condenser 52 condenses the direction changing mirror 521 for changing the direction of the pulse laser beam oscillated from the pulse laser beam oscillating means 51 downward in FIG. 2 and the pulse laser beam changed in direction by the direction changing mirror 521. And a condensing lens 522.

  As shown in FIG. 1, the imaging means 6 is disposed at a predetermined distance (L) on the same line in the X-axis direction from the condenser 52. The imaging unit 6 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, 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 the infrared rays captured by the optical system is used, and the captured image signal is sent to a control means to be described later.

  Continuing the description with reference to FIG. 1, the laser processing apparatus in the illustrated embodiment includes display means 7 disposed on the casing 42. The display means 7 displays an image taken by the imaging means 6 and the like.

  The laser processing apparatus in the illustrated embodiment includes the control means 8 shown in FIG. The control means 8 is constituted by a computer, and a central processing unit (CPU) 81 that performs arithmetic processing according to a control program, a read-only memory (ROM) 82 that stores a control program and the like, and a readable and writable memory that stores arithmetic results and the like. A random access memory (RAM) 83, an input interface 84 and an output interface 85 are provided. Detection signals from the X-axis direction position detection means 374, the Y-axis direction position detection means 384, the imaging means 6 and the like are input to the input interface 84 of the control means 8 configured as described above. A control signal is output from the output interface 85 of the control means 8 to the processing feed means 37, the index feed means 38, the pulse laser beam oscillation means 51 constituting the laser beam irradiation means 5, and the like.

The laser processing apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
FIG. 4 shows a perspective view of a semiconductor wafer as a workpiece. A semiconductor wafer 10 shown in FIG. 4 is formed of a silicon wafer, and devices 102 such as ICs and LSIs are formed in a plurality of regions partitioned by a plurality of streets 101 formed in a lattice shape on the surface 10a. As shown in FIG. 5, the semiconductor wafer 10 thus formed is attached to the protective tape T made of a synthetic resin sheet such as polyolefin and attached to the annular frame F (protective tape attaching step). ). Therefore, the surface 10a of the semiconductor wafer 10 is on the upper side.

  When performing laser processing along the street 101 of the semiconductor wafer 10 using the laser processing apparatus described above, it is necessary to confirm the positional relationship between the condenser 52 of the laser beam irradiation means 5 and the imaging means 6. is there. As described above, the image pickup means 6 is arranged at a predetermined distance (L) on the same line in the X-axis direction from the condenser 52 as described above, and this positional relationship is determined based on the random access memory (the control means 8). RAM) 83. However, the positional relationship between the condenser 52 and the imaging means 6 is shifted due to the thermal expansion or the like of the assembly parts constituting the laser processing apparatus. Therefore, a displacement amount detection operation for detecting the displacement amount between the light collector 52 and the imaging means 6 based on this shift is performed.

  In the displacement detection operation, first, the protective tape T side of the semiconductor wafer 10 is placed on the chuck table 36. Then, by operating a suction means (not shown), the semiconductor wafer 10 is sucked and held on the chuck table 36 via the protective tape T (wafer holding step). Therefore, the surface 10a of the semiconductor wafer 10 held on the chuck table 36 is on the upper side.

  If the semiconductor wafer 10 is sucked and held on the chuck table 36 as described above, the control means 8 operates the processing feed means 37 and the semiconductor wafer held on the chuck table 36 as shown in FIG. 10 is positioned directly below the condenser 52. This arbitrary detection part may be an outer peripheral part of the semiconductor wafer 10 where the device 102 is not formed. Next, the control means 8 operates the laser beam irradiating means 5 and irradiates the laser beam from the condenser 52, thereby marking (G) an arbitrary detection portion in the semiconductor wafer 10 as shown in FIG. (Laser beam marking process).

  If the laser beam marking process described above is performed, the control means 8 operates the processing feed means 37 and moves the chuck table 36 by a predetermined distance (L) in the X-axis direction as shown in FIG. Position on means 6. In this way, when the chuck table 36 holding the semiconductor wafer 10 is positioned directly below the imaging means 6, the semiconductor wafer 10 held on the chuck table 36 is imaged by the imaging means 6 and the captured image signal is controlled. Send to means 8. Based on the image signal sent from the imaging means 6, the control means 8 displays the image captured by the imaging means 6 on the display means 7 as shown in FIG. Thus, based on the image displayed on the display means 7, the operator can mark the marking G formed on an arbitrary detection portion of the semiconductor wafer 10 held on the chuck table 36 from the center P of the imaging area by the imaging means 6. The displacement amounts Δx and Δy displaced in the X and Y directions can be detected (displacement amount detection step). In the embodiment shown in FIG. 7B, the center of the spot of the laser beam irradiated from the condenser 52 is displaced from the center P of the imaging means 6 by plus Δx in the X-axis direction and minus Δy in the Y-axis direction. Will be displaced only. It should be noted that the positional relationship between the condenser 52 and the imaging means 6 is assembled as designed, and there is no deviation in the positional relationship between the condenser 52 and the imaging means 6 due to thermal expansion or the like. The marking G formed on the semiconductor wafer 10 coincides with the center P of the imaging means 6. When the displacement amounts Δx and Δy between the condenser 52 and the imaging means 6 are detected as described above, the control means 8 updates the displacement amount data stored in the random access memory (RAM) 83.

  If the displacement amount detecting operation for detecting the displacement amount between the condenser 52 and the imaging means 6 is performed as described above and the displacement amount data stored in the random access memory (RAM) 83 is updated, the chuck A predetermined laser processing is performed on the semiconductor wafer 10 held on the table 36 along the street.

  First, the control means 8 operates the processing feed means 37 to position the chuck table 36 that sucks and holds the semiconductor wafer 10 directly below the imaging means 6. When the chuck table 36 is positioned immediately below the image pickup means 6 in this way, the control means 8 operates the image pickup means 6 to execute an alignment process for detecting a processing region to be laser processed on the semiconductor wafer 10. That is, the control unit 8 constitutes the street 101 formed in a predetermined direction of the semiconductor wafer 10 based on the image signal captured by the imaging unit 6 and the laser beam irradiation unit 5 that irradiates the laser beam along the street 101. Image processing such as pattern matching for alignment with the condenser 52 is executed, and alignment of the laser beam irradiation position is performed. The alignment of the laser beam irradiation position 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 process is performed as described above, the machining feed means 37 and the index feed means 38 are operated to move the chuck table 36 to the laser beam irradiation region where the condenser 52 of the laser beam irradiation means 5 is located. 8A, one end of the predetermined street 101 (the left end in FIG. 8A) is positioned directly below the condenser 52. At this time, as described above, the condenser 52 and the imaging means 6 are displaced by plus (+) Δx in the X-axis direction and are displaced by minus (−) Δy in the Y-axis direction. By correcting the displacements Δx and Δy and moving the chuck table 36, as shown in FIG. 8A, one end of the predetermined street 101 (the left end in FIG. 8A) is connected to the condenser 52. Can be positioned directly below. Next, the control unit 8 operates the laser beam irradiation unit 5 to operate the processing feed unit 37 while irradiating the semiconductor wafer with a pulsed laser beam having an absorptivity to the semiconductor wafer. In FIG. 8A, it is moved at a predetermined feed speed in the direction indicated by the arrow X1 (laser machining groove forming step). Then, as shown in FIG. 8B, when the other end of the predetermined street 101 (the right end in FIG. 8B) reaches directly below the condenser 52, the irradiation of the pulse laser beam is stopped and the chuck table is stopped. The movement of 36 is stopped. Thus, when stopping the movement of the chuck table 36, the control means 8 controls the machining feed means 37 based on the detection signal from the X-axis direction position detection means 374. Since the displacement amount in the X-axis direction between the optical device 52 and the imaging means 6 is plus (+) Δx, the displacement amount (+) Δx is corrected and the movement of the chuck table 36 is stopped, as shown in FIG. As shown in b), the movement of the chuck table 36 can be stopped at a position where the other end of the predetermined street 101 (the right end in FIG. 8B) reaches just below the condenser 52. In this laser processing groove forming step, the condensing point P of the pulse laser beam is matched with the vicinity of the upper surface of the optical device wafer 10. As a result, the laser processing groove 110 is formed along the street 101 in the optical device wafer 10.

The processing conditions in the laser processing groove forming step are set as follows, for example.
Light source: YAG laser Wavelength: 355 nm pulse laser Repeat frequency: 10 kHz
Average output: 3.5W
Condensing spot diameter: φ30μm
Processing feed rate: 100 mm / sec

  As described above, when the laser processing groove forming step is performed along all the streets 101 formed in a predetermined direction of the semiconductor wafer 10, the position where the chuck table 36 holding the semiconductor wafer 10 is rotated by 90 degrees. Position. Then, the laser processing groove forming step is performed along all the streets 101 formed in the direction orthogonal to the predetermined direction of the semiconductor wafer 10.

  As described above, the semiconductor wafer 10 in which the laser processing groove forming process is performed along all the streets 101 is transferred to the wafer dividing process in which the semiconductor wafer 10 is broken along the street 101 in which the laser processing grooves 110 are formed.

  As described above, the displacement amount detection method and the laser processing apparatus in the illustrated embodiment operate the processing feed means 37 so that an arbitrary detection portion in the workpiece held on the chuck table 36 is directly below the condenser 52. The laser beam irradiating means 5 is operated to irradiate the laser beam from the condenser 52, so that an arbitrary detection portion in the semiconductor wafer 10 which is a workpiece held by the chuck table 36 is engraved, and then the processing feed The imaging region by the imaging means 6 of the marking formed on the semiconductor wafer 10 which is the workpiece held by the chuck table 36 is operated by operating the means 37 and moving the chuck table 36 by a predetermined distance to be positioned immediately below the imaging means 6. Since the displacement amounts Δx and Δy from the center of the image are obtained, the processing position detected by the imaging means 6 is positioned directly below the condenser 52. When attaching, the amount of displacement [Delta] x, by correcting the [Delta] y, can be subjected to accurate laser processing set machining position of the workpiece.

  In the illustrated embodiment, the displacement detection method and the laser processing apparatus according to the present invention position and mark an arbitrary detection portion of the workpiece held on the chuck table 36 immediately below the condenser 52, and then process the feed. Since the means 37 is operated to move the chuck table 36 by a predetermined distance and is positioned immediately below the image pickup means 6, it is a simple operation of obtaining the displacement amounts Δx and Δy from the center of the image pickup area by the image pickup means 6 of the marking. Even while laser processing is being performed on the workpiece, the processing can be easily performed, and the displacement amounts Δx and Δy between the condenser 52 and the imaging means 6 are updated to be updated. The movement amount of the chuck table 36 can be corrected based on the displacement amounts Δx and Δy.

2: Stationary base 3: Chuck table mechanism 36: Chuck table 37: Processing feed means 374: X-axis direction position detection means 38: Indexing feed means 384: Y-axis direction position detection means 4: Laser beam irradiation unit 5: Laser beam irradiation means 51: Pulse laser beam oscillation means 52: Condenser 522: Condensing lens 6: Imaging means 7: Display means 8: Control means 10: Semiconductor wafer
F: Ring frame
T: Protective tape

Claims (2)

A chuck table having a workpiece holding surface for holding a workpiece, a laser beam oscillation means for oscillating a laser beam for laser processing the workpiece held on the chuck table, and the laser beam oscillation means oscillated by the laser beam oscillation means Laser beam irradiating means having a condenser for condensing the laser beam, processing feed means for moving the chuck table and the laser beam irradiating means relative to the processing feed direction (X-axis direction), the chuck table and the laser beam Index feed means for relatively moving the irradiation means in the index feed direction (Y-axis direction) orthogonal to the X-axis direction, and X-axis direction position detection means for detecting the X-axis direction movement position of the chuck table by the machining feed means And Y axis direction position detection for detecting the movement position of the chuck table in the Y axis direction by the index feed means. The light condensing in a laser processing apparatus comprising: an exiting means; and an imaging means that images a processing region of a workpiece that is disposed at a predetermined distance in the X-axis direction from the condenser and is held by the chuck table. A displacement amount detection method for detecting a displacement amount between a device and the imaging means,
The processing feed means is operated to position an arbitrary detection portion of the workpiece held on the chuck table immediately below the light collector, and the laser beam irradiation means is operated to irradiate the laser beam from the light collector. A laser beam marking step for marking an arbitrary detection portion in the workpiece held by the chuck table;
After performing the laser beam marking step, the machining feed means is operated to move the chuck table by a predetermined distance so as to be positioned directly below the imaging means, and the marking formed on the workpiece held on the chuck table A displacement amount detecting step for obtaining a displacement amount in the X-axis direction and the Y-axis direction from the center of the imaging region of the imaging means,
A displacement detection method characterized by the above. A chuck table having a workpiece holding surface for holding a workpiece, a laser beam oscillation means for oscillating a laser beam for laser processing the workpiece held on the chuck table, and the laser beam oscillation means oscillated by the laser beam oscillation means Laser beam irradiating means having a condenser for condensing the laser beam, processing feed means for moving the chuck table and the laser beam irradiating means relative to the processing feed direction (X-axis direction), the chuck table and the laser beam Index feed means for relatively moving the irradiation means in the index feed direction (Y-axis direction) orthogonal to the X-axis direction, and X-axis direction position detection means for detecting the X-axis direction movement position of the chuck table by the machining feed means And Y axis direction position detection for detecting the movement position of the chuck table in the Y axis direction by the index feed means. An output means, an image pickup means for picking up an image of a processing region of a workpiece that is disposed at a predetermined distance in the X-axis direction from the light collector and held on the chuck table, and the light collector and the image pickup means. In a laser processing apparatus comprising a control means having a memory for storing a displacement amount,
The control means operates the processing feed means to position an arbitrary detection part in the workpiece held on the chuck table directly below the condenser, and operates the laser beam irradiation means to operate from the condenser. A laser beam marking step for marking an arbitrary detection portion in the workpiece held on the chuck table by irradiating a laser beam, and after performing the laser beam marking step, the processing feeding means is operated to operate the chuck table. Is moved by the predetermined distance and positioned immediately below the image pickup means, and the displacement in the X-axis direction and the Y-axis direction from the center of the image pickup area by the image pickup means of the mark formed on the workpiece held on the chuck table The displacement obtained by the displacement amount detection step is performed, and the displacement amount of the condenser and the imaging means stored in the memory is calculated. To update to,
Laser processing equipment characterized by that.

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