JP6013894B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus for performing laser processing on a workpiece such as a semiconductor wafer.

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

  As a method of dividing a wafer such as the above-described semiconductor wafer or optical device wafer along the street, laser processing grooves are formed by ablation processing by irradiating a pulse laser beam along the street formed on the wafer, and the wafer is formed. A method of dividing along the street has been proposed.

  A laser processing apparatus for performing laser processing on a workpiece includes a workpiece holding means for holding the workpiece, a laser beam irradiation means for irradiating a workpiece with the laser beam to the workpiece held by the workpiece holding means, Processing feed means for processing and feeding the workpiece holding means and the laser beam irradiation means relative to the processing feed direction, and indexing for feeding and feeding the workpiece holding means and the laser beam irradiation means in the index feeding direction orthogonal to the machining feed direction Feeding means are provided. Laser beam irradiating means includes laser beam oscillating means for oscillating a laser beam, a condenser for condensing the laser beam oscillated by the laser beam oscillating means and irradiating the workpiece held by the workpiece holding means, and laser beam oscillating means And an optical system such as an output adjusting means for adjusting the output of the laser beam, which is disposed between the optical condenser and the condenser. (For example, refer to Patent Document 1.)

JP 2006-253432 A

The optical system constituting the laser beam irradiation means of the laser processing apparatus has a fate that deteriorates with time.
However, since the deterioration of the optical system constituting the laser beam irradiation means cannot be detected, there is a problem that the processing quality of the workpiece is lowered.
For example, when the laser beam oscillation means including the laser beam oscillator is deteriorated, it is possible to maintain the processing quality of the workpiece by temporarily adjusting the output by controlling the output adjustment means. Since it is impossible to know, it is not possible to determine whether provisional measures are required or whether the laser beam oscillator needs to be replaced. There is a problem of inviting.

  The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is to provide a laser processing apparatus capable of self-diagnosis of deterioration of the laser beam irradiation means.

In order to solve the main technical problem, according to the present invention, a laser processing apparatus for laser processing a wafer formed by dividing a plurality of devices by streets while stepping a unit reticle on the surface of a substrate,
A workpiece holding means for holding a wafer, a laser beam irradiating means for irradiating a wafer held by the workpiece holding means with a laser beam, and the workpiece holding means and the laser beam irradiating means relative to each other in the X-axis direction. X-axis moving means for processing and feeding, Y-axis moving means for indexing and feeding the workpiece holding means and the laser beam irradiation means in the Y-axis direction orthogonal to the X-axis direction, and the workpiece holding means An imaging means for imaging a laser processing groove formed on a held wafer, and a control means for diagnosing the laser beam irradiation means based on the laser processing groove imaged by the imaging means,
The control means includes a memory for storing coordinate values of a plurality of unit reticles formed on a substrate constituting the wafer, and is stored in the memory in a laser processing groove formed on the wafer by operating the imaging means. A specific coordinate region of the same region of at least two unit reticles of a plurality of unit reticles is imaged, and self-diagnosis of the laser beam irradiation unit is performed based on changes in at least two laser processing grooves imaged by the imaging unit And display the diagnosis result on the display means,
A laser processing apparatus is provided.

  The change in the laser processed groove detects a change in the width dimension.

  The laser processing apparatus according to the present invention is configured to image a laser beam irradiating unit that irradiates a wafer held by a workpiece holding unit with a laser beam and a laser processing groove formed on the wafer held by the workpiece holding unit. And a control means for diagnosing the laser beam irradiation means based on the laser processing groove imaged by the imaging means, the control means obtaining the coordinate values of a plurality of unit reticles formed on the substrate constituting the wafer. A memory for storing is provided, and imaging means is operated to image a specific coordinate area of the same area of at least two unit reticles of a plurality of unit reticles stored in the memory in a laser processing groove formed on the wafer. The laser beam irradiation means self based on the change of at least two laser processing grooves imaged by the means Sectional then, since display means to display the diagnosis result, without variation by the device occurs, it is possible to accurately determine the deterioration of the laser beam irradiation means. As a result, the processing quality can be maintained by temporarily adjusting the output or exchanging the laser beam oscillator of the laser beam irradiation means.

The perspective view of the laser processing apparatus comprised according to this invention. The block block diagram of the laser beam irradiation means with which the laser processing apparatus shown in FIG. 1 is equipped. The block block diagram of 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. The plane which shows the state which affixed the semiconductor wafer shown in FIG. 4 on the dicing tape with which the cyclic | annular flame | frame was mounted | worn. FIG. 5 is an explanatory diagram showing a relationship with a coordinate position in a state where the semiconductor wafer shown in FIG. 4 is held at a predetermined position of a chuck table as a workpiece holding means of the laser processing apparatus shown in FIG. 1. Explanatory drawing of the laser processing groove | channel formation process implemented by the laser processing apparatus shown in FIG. Explanatory drawing of the laser processing groove | channel displayed on a display means by the laser processing groove | channel confirmation process implemented by the laser processing apparatus shown in FIG.

  Preferred embodiments of a laser processing apparatus configured according to the present invention will be described below in more 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 stationary base 2 and a chuck for holding a wafer as a workpiece, which 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. A table mechanism 3, a laser beam irradiation unit support mechanism 4 disposed on the stationary base 2 so as to be movable in an indexing feed direction (Y axis direction) indicated by an arrow Y orthogonal to the X axis direction, and the laser beam irradiation unit support mechanism 4 includes a laser beam irradiation unit 5 disposed so as to be movable in a condensing point position adjustment direction (Z-axis direction) indicated by an arrow Z.

  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 A cover table 35 supported by 34 and a chuck table 36 as a workpiece holding means are provided. The chuck table 36 includes a suction chuck 361 formed of a porous material, and holds, for example, a disk-shaped semiconductor wafer, which is a workpiece, on the suction chuck 361 by suction means (not shown). . 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 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 way 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 an X-axis moving means 37 for moving the first sliding block 32 along the pair of guide rails 31, 31 in the X-axis direction. The X-axis moving 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. Yes. 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, when the male screw rod 371 is driven forward and backward by the pulse motor 372, the first sliding block 32 is moved along the guide rails 31, 31 in the X-axis direction.

  The laser processing apparatus in the illustrated embodiment includes X-axis direction position detecting means 374 for detecting the processing feed amount of the chuck table 36, that is, the X-axis direction position. 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 counts the input pulse signal to detect the machining feed amount of the chuck table 36, that is, the position in the X-axis direction. When the pulse motor 372 is used as the drive source of the machining feed means 37, the machining feed amount of the chuck table 36 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 372. That is, the position in the X-axis direction can also be detected.

  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 a first Y for moving the second sliding block 33 in the Y-axis direction along a pair of guide rails 322 and 322 provided in the first sliding block 32. An axis moving means 38 is provided. The first Y-axis moving 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. Is included. One end of the male screw rod 381 is rotatably supported by a bearing block 383 fixed to the upper surface of the first slide 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 through female screw hole formed in a female screw block (not shown) provided on the lower surface of the center portion of the second sliding block 33. Therefore, the second sliding block 33 is moved in the Y-axis direction along the guide rails 322 and 322 by driving the male screw rod 381 forward and backward by the pulse motor 382.

  The laser processing apparatus in the illustrated embodiment includes Y-axis direction position detecting means 384 for detecting the indexing processing feed amount of the second sliding block 33, that is, the Y-axis direction position. The Y-axis direction position detecting means 384 moves along the linear scale 384a together with the linear scale 384a disposed along the guide rail 322 and the second sliding block 33. And a reading 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 counts the input pulse signal to detect the index feed amount of the chuck table 36, that is, the position in the Y-axis direction. When the pulse motor 382 is used as the drive source of the first Y-axis moving means 38, the chuck table 36 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 382. It is also possible to detect the index feed amount, that is, the position in the Y-axis direction.

  The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41 and 41 disposed in parallel along the Y-axis direction on the stationary base 2 and a direction indicated by an arrow Y on the guide rails 41 and 41. A movable support base 42 is provided so as to be movable. 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 Z-axis direction on one side surface in parallel. The laser beam irradiation unit support mechanism 4 in the illustrated embodiment includes second Y-axis moving means 43 for moving the movable support base 42 along the pair of guide rails 41 and 41 in the Y-axis direction. . The second Y-axis moving 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. Is included. 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. For this reason, when the male screw rod 431 is driven to rotate forward and reversely by the pulse motor 432, the movable support base 42 is moved along the guide rails 41, 41 in the Y-axis direction.

  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 Z-axis direction.

  The laser beam irradiation unit 5 in the illustrated embodiment includes a condensing point position adjusting means 53 for moving the unit holder 51 along the pair of guide rails 423 and 423 in the Z-axis direction. The condensing point position adjusting means 53 includes a male screw rod (not shown) disposed between the pair of guide rails 423 and 423, and a drive source such as a pulse motor 532 for rotationally driving the male screw rod. Thus, the unit holder 51 and the laser beam irradiation means 52 are moved along the guide rails 423 and 423 in the Z-axis direction by driving the male screw rod (not shown) by the pulse motor 532 in the normal direction and the reverse direction. In the illustrated embodiment, the laser beam irradiation means 52 is moved upward by driving the pulse motor 532 forward, and the laser beam irradiation means 52 is moved downward by driving the pulse motor 532 in reverse. Yes.

The illustrated laser beam application means 52 includes a cylindrical casing 521 that is fixed to the unit holder 51 and extends substantially horizontally. The laser beam irradiation means 52 will be described with reference to FIG.
The illustrated laser beam application means 52 includes a pulse laser beam oscillation means 522 disposed in the casing 521, an output adjustment means 523 for adjusting the output of the pulse laser beam oscillated by the pulse laser beam oscillation means 522, and the output adjustment. A condenser 524 for irradiating the workpiece W held on the holding surface of the chuck table 36 with the pulse laser beam whose output is adjusted by the means 523 is provided.

  The pulse laser beam oscillation means 522 includes a pulse laser beam oscillator 522a that oscillates a pulse laser beam, and a repetition frequency setting means 522b that sets a repetition frequency of the pulse laser beam oscillated by the pulse laser beam oscillator 522a. The output adjusting unit 523 adjusts the output of the pulse laser beam oscillated from the pulse laser beam oscillating unit 522 to a predetermined output. The pulse laser beam oscillator 522a, the repetition frequency setting unit 522b, and the output adjustment unit 523 of the pulse laser beam oscillation unit 522 are controlled by a control unit (not shown) to be described later.

  The condenser 524 includes a direction changing mirror 524a for changing the direction of the pulse laser beam oscillated from the pulse laser beam oscillating means 522 and having the output adjusted by the output adjusting means 523 toward the holding surface of the chuck table 36, and the direction changing mirror. A condensing lens 524b for condensing the pulse laser beam whose direction has been changed by 524a and irradiating the workpiece W held on the chuck table 36 is provided. The concentrator 524 configured in this way is attached to the tip of the casing 521 as shown in FIG.

  Returning to FIG. 1, the description is continued. At the tip of the casing 521 constituting the laser beam irradiation means 52, an imaging means 6 for detecting a processing region to be laser processed by the laser beam irradiation means 52 is disposed. The image pickup means 6 is composed of an optical system such as a microscope and an image pickup device (CCD), and sends the picked-up image signal to a control means described later.

  The laser processing apparatus in the illustrated embodiment includes a control means 7 shown in FIG. The control means 7 is constituted by a computer, and a central processing unit (CPU) 71 that performs arithmetic processing according to a control program, a read only memory (ROM) 72 that stores a control program and the like, and a design value of a workpiece to be described later. A readable / writable random access memory (RAM) 73 that stores data, calculation results, and the like, a counter 74, an input interface 75, and an output interface 76 are provided. Detection signals from the X-axis direction position detection unit 374, the Y-axis direction position detection unit 384, the imaging unit 6 and the like are input to the input interface 75 of the control unit 7, and an input signal is input from the input unit 77. The From the output interface 76 of the control means 7, the pulse motor 372, the pulse motor 382, the pulse motor 432, the pulse motor 532, the pulse laser beam oscillator 522a of the laser beam irradiation means 52, the repetition frequency setting means 522b, the output adjustment means 523, etc. A control signal is output to the display means 70 and a display signal is output to the display means 70.

Next, a method for forming a laser processing groove on a wafer as a workpiece using the laser processing apparatus described above will be described.
FIG. 4 shows a perspective view of a semiconductor wafer as a workpiece. A semiconductor wafer 10 shown in FIG. 4 includes, for example, a plurality of devices 101 and a plurality of first streets 102 orthogonal to the first streets 102 while stepping the unit reticle 100 on a surface 10a of a silicon substrate having a thickness of 200 μm. It is divided and formed by the street 103. Note that the unit reticle 100 includes six devices 101 partitioned by a plurality of first streets 102 and second streets 103 in the illustrated embodiment.

  4, the back surface of the semiconductor wafer 10 shown in FIG. 4 is attached to the surface of the dicing tape T attached to the annular frame F as shown in FIG. 5 (wafer attaching step). Therefore, the surface 10a of the semiconductor wafer 10 attached to the surface of the dicing tape T is on the upper side.

  If the wafer sticking step described above is performed, the dicing tape T side of the semiconductor wafer 10 is placed on the chuck table 36 of the laser processing apparatus shown in FIG. Then, the semiconductor wafer 10 is sucked and held on the chuck table 36 via the dicing tape T by operating a suction means (not shown) (wafer holding step). Therefore, the surface 10a of the semiconductor wafer 10 held on the chuck table 36 is on the upper side. The annular frame F 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 6 by the X-axis moving unit 37. When the chuck table 36 is positioned immediately below the image pickup means 6 in this way, an alignment operation for detecting a processing region to be laser processed on the semiconductor wafer 10 is executed by the image pickup means 6 and the control means 7. That is, the imaging means 6 and the control means 7 are the first street 102 formed in a predetermined direction of the semiconductor wafer 10 and the laser beam irradiating means 52 that irradiates the laser beam along the first street 102. Image processing such as pattern matching for alignment with the optical device 524 is executed, and alignment of the laser beam irradiation position is performed. Similarly, the alignment of the laser beam irradiation position is also performed on the second street 103 formed in the semiconductor wafer 10 and extending in a direction orthogonal to the first street 102.

  When alignment is performed as described above, the semiconductor wafer 10 on the chuck table 36 is positioned at the coordinate position shown in FIG. FIG. 6B shows a state in which the chuck table 36, that is, the semiconductor wafer 10, is rotated 90 degrees from the state shown in FIG.

  As described above, the design coordinate values of the plurality of unit reticles 100 in the semiconductor wafer 10 positioned at the coordinate positions shown in FIGS. 6A and 6B are the random access memory of the control means 7. (RAM) 73. In the state of FIG. 6A, a plurality of specific coordinates A1, A2, A3 of the first street 102 in the same region in the unit reticle 100 are selected, and the specific coordinates A1, A2, A3 are randomly selected. It is stored in an access memory (RAM) 73. In the state of FIG. 6B, a plurality of specific coordinates B1, B2, B3 of the second street 103 in the same region in the unit reticle 100 are selected, and the specific coordinates B1, B2, B3 are randomly selected. It is stored in an access memory (RAM) 73. The plurality of specific coordinates of the first street 102 and the plurality of specific coordinates B1, B2, B3 of the second street 103 in the same region in the unit reticle 100 are selected by a plurality of devices included in the unit reticle 100. Each 101 has individuality and is not necessarily the same. Therefore, by specifying the same street that divides devices having the same individuality, the variation in processing due to individuality is eliminated.

  In the example described above, the design coordinate values of the plurality of unit reticles 100 in the semiconductor wafer 10 and the plurality of specific coordinates A1, A2, A3 and the second streets 103 of the first street 102 in the same region in the unit reticle 100 are used. In the above example, a plurality of specific coordinates B1, B2, and B3 are stored in advance in a random access memory (RAM) 73 of the control means 7, but a plurality of unit reticles 100 in the semiconductor wafer 10 held on the chuck table 36 are operated by an operator. May be detected and the specific coordinates may be input from the input means 77.

  When the alignment process is performed as described above, the chuck table 36 is moved so that the lowest first street 102 is positioned immediately below the condenser 524 of the laser beam irradiation means 52 in FIG. Further, as shown in FIG. 7A, one end of the first street 102 (the left end in FIG. 7A) is positioned directly below the condenser 524. Then, the condensing point P of the pulse laser beam irradiated through the condenser 524 is positioned near the surface 10 a (upper surface) of the semiconductor wafer 10.

  Next, the laser beam irradiating means 52 is operated to irradiate a pulse laser beam through the condenser 524, and the X-axis moving means 37 is operated to move the chuck table 36 in a direction indicated by an arrow X1 in FIG. Move at machining feed rate. When the irradiation position of the condenser 524 of the laser beam irradiation means 52 reaches the position of the other end of the first street 102 (the right end in FIG. 7B) as shown in FIG. The laser beam irradiation is stopped and the movement of the chuck table 36 is stopped (laser machining groove forming step). As a result, a laser processed groove 110 is formed along the first street 102 in the wafer 10 as shown in FIGS. 7B and 7C.

The processing conditions in the laser processing groove forming step are set as follows, for example.
Light source: Semiconductor pumped solid-state laser (Nd: YAG)
Wavelength: 355nm
Repetition frequency: 100 kHz
Average output: 3W
Condensing spot diameter: φ10μm
Processing feed rate: 100 mm / sec

  As described above, when the laser processing groove forming step is performed along the lowest first street 102 in FIG. 6A of the semiconductor wafer 10, the first Y-axis moving means 38 is activated. Then, the chuck table 36 is moved in the Y-axis direction by the interval of the first streets 102, and the second first street 102 from the lowest position is positioned directly below the condenser 524 of the laser beam irradiation means 52. Then, the laser processing groove forming step is performed along the second first street 102 from the bottom.

  In this way, when the laser machining groove forming step is performed along the second first street 102 from the bottom in FIG. 6A, the X-axis moving means 37 is operated to operate the chuck table 36. The specific coordinate A1 of the semiconductor wafer 10 held on the substrate is positioned directly below the imaging means 6. Then, the control unit 7 operates the imaging unit 6 to image the laser processing groove 110 formed along the first street 102 at the specific coordinate A1, and the imaging unit 6 sends the captured image signal to the control unit 7. . The control means 7 obtains the width dimension of the laser processing groove 110 based on the image signal sent from the imaging means 6, displays the width dimension L A1 together with the laser processing groove 110 on the display means 70 as shown in FIG. It is stored in the random access memory (RAM) 73 as the width dimension L A1 of the specific coordinate A1 (laser machining groove confirmation step).

  Thereafter, in FIG. 6A, the laser processing groove forming step is sequentially performed from the third first street 102 from the lowest to the highest first street 102, and the specific coordinate A2 is located. If the laser processing groove forming step is performed along one street 102, the specific coordinate A2 of the semiconductor wafer 10 is positioned immediately below the imaging means 6, and the laser processing groove checking step is performed. Then, the width dimension L A2 is displayed on the display means 70 together with the laser processing groove 110 at the specific coordinate A2, and further stored in a random access memory (RAM) 73. At this time, when the width dimension L A1 of the laser processing groove 110 at the specific coordinate A1 is, for example, 10 μm and the width dimension L A2 of the laser processing groove 110 at the specific coordinate A2 is 10 μm, the laser processing groove 110 does not change and is controlled. The means 7 determines that each element constituting the laser beam irradiation means 52 has not deteriorated, and performs the laser processing groove forming step. Then, if the laser processing groove forming step is performed along the first street 102 where the specific coordinate A3 is located, the specific coordinate A3 of the semiconductor wafer 10 is positioned directly below the imaging means 6, and the laser processing groove confirmation step is performed. carry out. Next, the width dimension L A3 is displayed on the display means 70 together with the laser processing groove 110 at the specific coordinate A3 and further stored in a random access memory (RAM) 73. At this time, when the width dimension L A3 of the laser processing groove 110 at the specific coordinate A3 is 9 μm, for example, the laser processing groove 110 has changed, and the control means 7 determines that the laser beam irradiation means 52 has deteriorated (self (Diagnosis step), and the output from the output adjustment means 523 of the laser beam irradiation means 52 is controlled to be, for example, 3.2 W, and the diagnosis result is displayed on the display means 70. Thereafter, the laser processing groove forming step is performed along the uppermost first street 102 in FIG. 6A in a state where the output from the output adjusting means 523 of the laser beam irradiation means 52 is adjusted to 3.2 W, for example. To do.

  As described above, when the laser processing groove forming step is performed along all the first streets 102 extending in a predetermined direction of the semiconductor wafer 10, the chuck table 36 is rotated by 90 degrees to turn the semiconductor wafer. 10 is changed to the state shown in FIG. 6B, and the laser processing groove forming step is performed along the second street 103, and the second coordinate 103 along which the specific coordinate B1, B2, and B3 regions are located. After performing the laser processing groove forming step, the laser processing groove confirmation step and the self-diagnosis step are performed, respectively. It should be noted that the difference between the width dimension of the laser processing groove 110 in the previous specific coordinate area and the width dimension of the laser processing groove 110 in the specific coordinate area detected this time in the laser processing groove confirmation process and the self-diagnosis process is, for example, 20% or more. The control means 7 determines that the pulse laser beam oscillator 522a of the laser beam irradiation means 52 has deteriorated and has reached the end of its life, and displays that fact on the display means 70.

In the embodiment described above, the specific coordinates A1, A2, A3 and the specific coordinates B1, B2, B3 of the first street 102 and the second street 103 in the same region in the unit reticle 100 are selected, and the specific coordinates A1, A2, A3 and specific coordinates B1, B2, B3 are stored in a random access memory (RAM) 73, and the first street 102 where the specific coordinates A1, A2, A3 and the specific coordinates B1, B2, B3 are located and Each time the laser processing groove forming step is performed along the second street 103, the state of the laser processing groove 110 formed in the specific coordinate area is detected, so that the deterioration of the laser beam irradiation means 52 is accurately detected. Can be determined.
In the above-described embodiment, the example in which the deterioration of the laser beam irradiation means 52 is determined by the reduction in the width dimension of the laser processing groove 110 formed in the specific coordinate region has been described. The deterioration of the laser beam irradiation means 52 may be determined by detecting a decrease in scattered debris.

2: stationary base 3: chuck table mechanism 36: chuck table 37: X-axis moving means 38: first Y-axis moving means 4: laser beam irradiation unit support mechanism 43: second Y-axis moving means 5: laser beam irradiation unit 52: Laser beam irradiation means 524: Condenser 53: Condensing point position adjusting means 6: Imaging means 7: Control means 70: Display means 10: Semiconductor wafer F: Ring frame T: Dicing tape

Claims (2)

A laser processing apparatus for laser processing a wafer formed by dividing a plurality of devices by streets while stepping a unit reticle on the surface of a substrate,
A workpiece holding means for holding a wafer, a laser beam irradiating means for irradiating a wafer held by the workpiece holding means with a laser beam, and the workpiece holding means and the laser beam irradiating means relative to each other in the X-axis direction. X-axis moving means for processing and feeding, Y-axis moving means for indexing and feeding the workpiece holding means and the laser beam irradiation means in the Y-axis direction orthogonal to the X-axis direction, and the workpiece holding means An imaging means for imaging a laser processing groove formed on a held wafer, and a control means for diagnosing the laser beam irradiation means based on the laser processing groove imaged by the imaging means,
The control means includes a memory for storing coordinate values of a plurality of unit reticles formed on a substrate constituting the wafer, and is stored in the memory in a laser processing groove formed on the wafer by operating the imaging means. A specific coordinate region of the same region of at least two unit reticles of a plurality of unit reticles is imaged, and self-diagnosis of the laser beam irradiation unit is performed based on changes in at least two laser processing grooves imaged by the imaging unit And display the diagnosis result on the display means,
Laser processing equipment characterized by that.   The laser processing apparatus according to claim 1, wherein the change in the laser processing groove detects a change in a width dimension.

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