KR20160096551A - Laser machining apparatus - Google Patents

Abstract

The present invention relates to a laser machining apparatus capable of simultaneously forming holes at a plurality of positions without generating cracks. The laser machining apparatus comprises: a chuck table which maintains a processing object on an XY plane; and a laser beam irradiation means which irradiates the processing object maintained on the chuck table with a laser beam. The laser beam irradiation means includes a pulse laser beam oscillation means which oscillates a pulse laser beam at repetition frequency M, a condenser which condenses the pulse laser beam oscillated by the pulse laser beam oscillation means, and irradiates the processing object maintained on the chuck table, and a pulse dispersion means which is disposed and formed between the pulse laser beam oscillation means and the condenser, and disperses the pulse laser beam on a plurality of X coordinates and a plurality of Y coordinates, and the pulse dispersion means includes a mirror which reflects the pulse laser beam oscillated at the repetition frequency M, and includes a scanner which fluctuates at repetition frequency M1 lower than the repetition frequency M and disperses the pulse laser beam on (M/M1) coordinates.

Description

[0001] LASER MACHINING APPARATUS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for performing laser processing on a workpiece such as a semiconductor wafer.

In a semiconductor device manufacturing process, a plurality of regions are partitioned by a line to be divided which is arranged in a lattice on the surface of a semiconductor wafer which is substantially in the shape of a disk, and a device such as IC or LSI is formed in the partitioned region. Then, the semiconductor wafer is cut along the line to be divided, thereby dividing the region where the device is formed to manufacture individual semiconductor device chips.

A module structure in which a plurality of semiconductor chips are stacked and electrodes of a plurality of stacked semiconductor devices are connected is put to practical use in order to make the device compact and highly functional. In this module structure, a laser beam is irradiated from a back surface corresponding to a point where an electrode is formed on a semiconductor wafer to form a through hole for burying an electrode, and a conductive material such as copper or aluminum (For example, Patent Document 1).

Japanese Laid-Open Patent Publication No. 2008-62261

However, as described above, in order to form a through hole by laser machining, it is necessary to irradiate a plurality of pulsed laser beams at one point (through-hole boring position), so that the repetition frequency of the pulsed laser beam is increased, It is desirable to improve the performance of the apparatus.

However, when a pulsed laser beam is irradiated to a point at a plurality of times with a high repetition frequency, a heat accumulation crack is generated and the quality of the device is deteriorated.

According to the experiment of the inventor of the present invention, it was found that the maximum repetition frequency that does not cause cracks when forming the through holes is 10 kHz.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is a main object of the present invention to provide a laser machining apparatus capable of simultaneously forming through holes at a plurality of positions without generating cracks.

According to the present invention, there is provided a laser machining apparatus comprising a chuck table for holding a workpiece in an XY plane, a laser beam irradiating means for irradiating a laser beam to a workpiece held on the chuck table, The laser beam irradiating means includes pulse laser beam oscillation means for oscillating a pulsed laser beam at a repetition frequency M, means for condensing the pulsed laser beam oscillated by the pulsed laser beam oscillation means, And a pulse dispersing means which is disposed between the pulsed laser beam emitting means and the condenser and disperses the pulsed laser beam into a plurality of X coordinates and a plurality of Y coordinates, , A mirror for reflecting pulsed laser light oscillated at the repetition frequency M, Swings to the repetition frequency of M1 to (M / M1) of coordinates of the laser machining apparatus characterized in that comprises a scanner for distributing the pulse laser beam is provided.

Preferably, the pulse dispersing means includes Y-coordinate dispersing means for dispersing the pulsed laser beam into a plurality of Y-coordinates, and X-coordinate dispersing means for dispersing the plurality of X-

The Y coordinate distribution means includes a first main scanner that oscillates at a repetition frequency M1 and a first beam scanner that oscillates at a repetition frequency of an integer multiple of the repetition frequency M1 to disperse the pulsed laser light , The phase of the repetition frequency of the first main scanner and the first beam scanner thereof is shifted to specify the Y coordinate to which the pulsed laser beam is irradiated,

The X-coordinate spreading means includes a second main scanner that oscillates at a repetition frequency M1 and a second beam scanner that oscillates at a repetition frequency that is an integral multiple of the repetition frequency M1 to disperse the pulsed laser beams, And the phase of the repetition frequency of the second beam scanner are shifted to specify the X coordinate to which the pulsed laser beam is irradiated.

The laser machining apparatus according to the present invention is characterized in that the laser beam irradiating means for irradiating the workpiece held on the chuck table held in the XY plane comprises pulse laser beam oscillation means for oscillating the pulse laser beam at the repetition frequency M, A condenser for condensing the pulsed laser beam oscillated by the pulsed laser beam oscillation means and for irradiating the workpiece held by the workpiece holding means, a pulsed laser beam arranged between the pulsed laser beam oscillation means and the condenser and having a plurality of X Coordinates and a plurality of Y coordinates, wherein the pulse dispersing means has a mirror for reflecting the pulsed laser beam oscillated at the repetition frequency M and oscillates at a repetition frequency M1 lower than the repetition frequency M (M / M1 ) Coordinates of the pulsed laser beam, it is possible to prevent the workpiece When a through hole is formed at the X coordinate and the Y coordinate position corresponding to the fixed coordinates, it is possible to simultaneously irradiate the pulsed laser beam with a plurality of coordinates at the maximum repetition frequency that does not cause cracking, and productivity is improved.

1 is a perspective view of a laser machining apparatus according to an embodiment of the present invention;
Fig. 2 is a block diagram of a laser beam irradiation means provided in the laser machining apparatus shown in Fig. 1. Fig.
Fig. 3 is a block diagram showing a Y-coordinate dispersing means constituting the laser beam irradiation means shown in Fig. 2; Fig.
Fig. 4 is a graph showing the relationship between the repetition frequency M01 (30 kHz) of the first borequitencer scanner constituting the Y coordinate dispersion means shown in Fig. 3, the repetition frequency M02 (20 kHz) of the second bore- And a summation repetition frequency MY obtained by summing the repetition frequencies M01 (30 kHz), M02 (20 kHz), and M1 (10 kHz).
Fig. 5 is a block diagram showing an X-coordinate distribution means constituting the laser beam irradiation means shown in Fig. 2; Fig.
Fig. 6 is a graph showing the relationship between the repetition frequency M01 (30 kHz) of the first borequiten scanner and the repetition frequency M02 (20 kHz) of the second borezone scanner constituting the X coordinate dispersing means shown in Fig. 5, (10 kHz) of the repetition frequency M01 (30 kHz), M02 (20 kHz) and M1 (10 kHz), respectively.
FIG. 7 is an explanatory diagram showing coordinates for irradiating a pulsed laser beam emitted from the pulsed laser beam oscillation means by means of pulse dispersion means comprising Y-coordinate dispersion means shown in FIG. 3 and X-coordinate dispersion means shown in FIG.
Fig. 8 is a block diagram of control means provided in the laser machining apparatus shown in Fig. 1. Fig.
9 is a perspective view of a semiconductor wafer as a workpiece;
Fig. 10 is a perspective view showing a state in which the semiconductor wafer shown in Fig. 9 is attached (adhered) to an adhesive tape mounted on an annular frame. Fig.
Fig. 11 is an explanatory diagram of a laser machining process performed by the laser machining apparatus shown in Fig. 1; Fig.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a laser machining apparatus constructed in accordance with the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a perspective view of a laser machining apparatus 1 according to an embodiment of the present invention. The laser machining apparatus 1 shown in Fig. 1 is provided with a stationary base 2 and a stationary base 2 which are arranged so as to be movable in the X-axis direction which is a processing transfer direction indicated by an arrow X in the stationary base 2, A chuck table mechanism 3 for holding a workpiece and a laser beam irradiation unit 4 as laser beam irradiation means arranged on the base 2. [

The chuck table mechanism 3 includes a pair of guide rails 31 and 31 formed on the stopper base 2 in parallel along the X axis direction and a pair of guide rails 31 and 31 on the guide rails 31 and 31, (Y) direction, which is an output transfer direction indicated by an arrow Y perpendicular to the X-axis direction, on the first active block 32. The first active block 32 is movable in a Y- A support table 35 supported by the cylindrical member 34 on the second active block 33 and a workpiece holding means 35 for holding the workpiece in the XY plane, And a chuck table 36 as a chuck table. The chuck table 36 is provided with a chucking chuck 361 made of a porous material and a circular semiconductor wafer, for example, a workpiece, which is a workpiece, is placed on a holding surface, which is an upper surface of the chucking chuck 361, Respectively. The chuck table 36 thus configured 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 for supporting a workpiece such as a semiconductor wafer through a protective tape.

The first active block 32 is formed with a pair of to-be-guided grooves 321 and 321 on the bottom surface thereof to be fitted with the pair of guide rails 31 and 31, A pair of guide rails 322 and 322 formed parallel to each other are formed. The first active block 32 constructed as described above is configured such that the guided grooves 321 and 321 are fitted to the pair of guide rails 31 and 31 so that X And is configured to be movable in the axial direction. The chuck table mechanism 3 according to the present embodiment includes an X axis direction moving means 37 for moving the first active block 32 along the pair of guide rails 31 and 31 in the X axis direction Respectively. The X-axis direction moving means 37 includes a male screw rod 371 formed parallel to the pair of guide rails 31 and 31 and a pulse motor 372 for rotating the male screw rod 371, And the like. One end of the male screw rod 371 is supported so as to freely rotate in a bearing block 373 fixed to the stationary base 2 and the other end thereof is transmitted to the output shaft of the pulse motor 372, It is connected. The male screw rod 371 is screwed to a through-hole formed in a female screw block (not shown) formed to protrude from a central bottom surface of the first active block 32. Therefore, the first active block 32 is moved in the X-axis direction along the guide rails 31, 31 by rotating the male screw rod 371 by the pulse motor 372 in a forward direction and a reverse direction do.

The laser machining apparatus 1 is provided with X-axis direction position detection means 374 for detecting the X-axis direction position of the chuck table 36. The X- The X-axis direction position detecting means 374 includes a linear scale 374a disposed along the guide rail 31 and a linear scale 374a disposed in the first active block 32 and coupled with the first active block 32, And a read head 374b that moves along the optical axis 374a. In the present embodiment, the read head 374b of the X-axis direction position detecting means 374 sends a pulse signal of one pulse every 1 占 퐉 to a control means described later. The control means, which will be described later, detects the position of the chuck table 36 in the X-axis direction by counting the inputted pulse signals. When the pulse motor 372 is used as the driving source of the processing and conveying means 37, the driving pulses of the control means described later for outputting the driving signal to the pulse motor 372 are counted, It is also possible to detect the position in the X-axis direction. When a servo motor is used as the driving source of the X-axis direction moving means 37, a pulse signal output from a rotary encoder for detecting the number of rotations of the servo motor is sent to a control means described later, The X-axis direction position of the chuck table 36 can be detected by counting the signals.

The second active block 33 includes a pair of guided grooves 331 and 331 for engaging with a pair of guide rails 322 and 322 formed on the upper surface of the first active block 32 And is configured so as to be movable in the Y-axis direction by fitting the guided grooves 331 and 331 into the pair of guide rails 322 and 322. The chuck table mechanism 3 includes Y-axis direction moving means for moving the second active block 33 along the pair of guide rails 322 and 322 formed in the first active block 32 in the Y-axis direction 38). The Y axis direction moving means 38 includes a male screw rod 381 arranged parallel to the pair of guide rails 322 and 322 and a pulse motor 382 for rotationally driving the male screw rod 381, And the like. One end of the male screw rod 381 is supported so as to freely rotate on a bearing block 383 fixed on the upper surface of the first active block 32 and the other end is supported on the output shaft of the pulse motor 382 It is electrically connected. The male screw rod 381 is screwed to a through-hole formed in a female screw block (not shown) formed to protrude from the center bottom face of the second active block 33. Thus, the second active block 33 is moved in the Y-axis direction along the guide rails 322 and 322 by driving the screw rod 381 by the pulse motor 382 in the forward and reverse directions.

The laser machining apparatus 1 is provided with a Y-axis direction position detecting means 384 for detecting the Y-axis direction position of the second active block 33. [ The Y-axis direction position detection means 384 includes a linear scale 384a formed along the guide rail 322 and a linear scale 384a arranged in the second active block 33 and coupled with the second active block 33, 384a. ≪ / RTI > In the present embodiment, the read head 384b of the Y-axis direction position detecting means 384 sends a pulse signal of one pulse every 1 占 퐉 to a control means described later. The control means, which will be described later, detects the position of the chuck table 36 in the Y-axis direction by counting the inputted pulse signals. When the pulse motor 382 is used as the driving source of the Y-axis direction moving means 38, the driving pulses of the control means described later for outputting the driving signal to the pulse motor 382 are counted, In the Y-axis direction. When a servo motor is used as the driving source of the Y-axis direction moving means 38, a pulse signal output from a rotary encoder for detecting the number of rotations of the servo motor is sent to a control means described later, It is also possible to detect the position of the chuck table 36 in the Y-axis direction by counting signals.

The laser beam irradiation unit 4 includes a support member 41 disposed on the base 2, a casing 42 supported substantially by the support member 41 and extending substantially horizontally, (50) formed on the front end of the casing (42) and detecting a machining area to be laser machined. The laser beam irradiating means (5) The imaging means 50 includes illumination means for illuminating a workpiece, an optical system for capturing an area illuminated by the illumination means, and an imaging element (CCD) for imaging an image captured by the optical system And sends the captured image signal to the control means described later.

The laser beam irradiation means 5 will be described with reference to Fig. 2, the laser beam irradiating means 5 includes a pulsed laser beam oscillation means 51 and a pulsed laser beam oscillation means 51 for condensing the pulsed laser beam and holding it on the chuck table 36 And a pulsed laser beam oscillated from the pulsed laser beam oscillation means 51 arranged between the pulsed laser beam oscillation means 51 and the condenser 52 to a plurality of Y coordinate and X coordinate, and optical path deflecting means 9 for deflecting the pulsed laser beam dispersed by the pulse dispersing means 6 in the X-axis direction. The pulse laser beam oscillation means 51 comprises a pulse laser oscillator 511 and a repetition frequency setting means 512 attached thereto. The pulse laser oscillator 511 of the pulse laser beam oscillation means 51 oscillates a pulse laser beam LB having a wavelength of 355 nm in this embodiment. The repetition frequency M of the pulse laser beam LB oscillated by the pulse laser beam oscillation means 51 is set to 40 kHz in the present embodiment. The condenser 52 is a pulse laser beam oscillated from the pulsed laser beam oscillation means 51 and guided through the Y coordinate dispersion means 7 and the X coordinate dispersion means 8 and the optical path deflection means 9 And a condenser lens 521 composed of an f? Lens for condensing the light beam LB.

The pulse dispersing means 6 disposed between the pulsed laser beam emitting means 51 and the condenser 52 is a device in which a plurality of pulsed laser beams LB oscillated from the pulsed laser beam emitting means 51 Coordinate dispersing means 8 for dispersing a pulse laser beam LB dispersed in Y coordinates by a Y-coordinate dispersing means 7 into a plurality of X-coordinates, ). The Y coordinate distribution means 7 includes a first borequiten scanner 71 having a reflection mirror 711 and a second borequincent scanner 72 having a reflection mirror 721 as shown in Fig. And a main resonant scanner 73 provided with a reflecting mirror 731. [

The first boresignant scanner 71 oscillates in response to the repetition frequency set by the frequency setter 712 and the second boresignant scanner 72 oscillates in response to the repetition frequency set by the frequency setter 722 And the main resonant scanner 73 is configured to pivot in response to the repetition frequency set by the frequency setter 732. [ The frequency setter 712 sets the repetition frequency M01 of the first boresignal scanner 71 to 30 kHz and the frequency setter 722 sets the repetition frequency M02 of the second boresignant scanner 72 to 20 kHz And the frequency setter 732 sets the repetition frequency M1 of the main resident scanner 73 to 10 kHz. The first repetition frequency M01 of the resonant scanner 71 and the repetition frequency M02 of the second boresignant scanner 72 are set to an integral multiple of the repetition frequency M1 of the main resident scanner 73. [

The main resonant scanner 73 that oscillates at the repetition frequency M1 disperses the pulsed laser beam LB oscillated at the repetition frequency M in the (M / M1) Y coordinates. The repetition frequency M of the pulsed laser beam LB oscillated by the pulsed laser beam oscillation means 51 is set to 40 kHz and the repetition frequency M1 of the main resonant scanner 73 is set to 10 kHz , The main Resonant scanner 73 is dispersed every (1/4) x (1/10 k) seconds in the Y coordinate of 4 (40/10). The intervals of the four Y coordinates distributed by the main Resonant scanner 73 are set so as to correspond to the intervals of the Y coordinates of the bonding pads formed on the devices of the semiconductor wafer, which will be described later, in the present embodiment .

The Y coordinate spreading means 7 is constituted as described above and the pulse laser beam LB oscillated from the pulsed laser beam oscillation means 51 is incident on the reflection mirror 711 of the first boresignal scanner 71 do. First pulse laser beam LB incident on the reflection mirror 711 of the resonant scanner 71 is reflected by the reflection mirror 721 of the second borequiten scanner 72 and the reflected laser beam LB of the main resonant scanner 73 And is emitted via the reflection mirror 731. [

4 shows the relationship between the repetition frequency M01 (30 kHz) of the first boresignal scanner 71, the repetition frequency M02 (20 kHz) of the second boresignant scanner 72, A graph showing a repetition frequency M1 (10 kHz) and a summation repetition frequency MY obtained by adding the repetition frequencies M01 (30 kHz), M02 (20 kHz) and M1 (10 kHz) is shown. In Fig. 4, the horizontal axis represents time (1/10 k) seconds, and the vertical axis represents Y coordinate. The pulsed laser beam LB oscillated from the pulsed laser beam oscillation means 51 is summed from the reflection mirror 731 of the main resonant scanner 73 every (1/4) x (1/10 k) Four (I Ⅱ Ⅲ Ⅳ) are emitted in the Y coordinate corresponding to the summation repetition frequency MY. The Y coordinates of the four pulsed laser beams LB outputted from the reflection mirror 731 of the main resonant scanner 73 are the same as the Y coordinate of the repetition frequency M1 ( (30 kHz) of the first borequencer scanner 71 and the phase of the repetition frequency M02 (20 kHz) of the second borequiten scanner 72 are shifted from each other.

Next, the X-coordinate distribution means 8 constituting the pulse dispersion means 6 will be described with reference to Fig. In the present embodiment, the X-coordinate distribution means 8 rotates the Y-coordinate dispersion means 7 by 90 degrees with the optical path of the laser beam LB emitted from the pulsed laser beam emission means 51 as a rotation axis A first boresignant scanner 81 having a reflection mirror 811 and a second boresignant scanner 82 having a reflection mirror 821 and a second boresight scanner 82 having a reflection mirror 821, And a main resident scanner 83 provided with a main scanning unit 831.

The first boresignant scanner 81 oscillates in response to the repetition frequency set by the frequency setter 812 and the second boresignant scanner 82 oscillates in response to the repetition frequency set by the frequency setter 822 And the main resident scanner 83 is configured to pivot in response to the repetition frequency set by the frequency setter 832. [ The frequency setter 812 sets the repetition frequency M01 of the first boresignal scanner 81 to 30 kHz and the frequency setter 822 sets the repetition frequency M02 of the second boresignant scanner 82 to 20 kHz And the frequency setter 832 sets the repetition frequency M1 of the main resident scanner 83 to 10 kHz. First Repetition Frequency M01 of the Resonant Scanner 81 and Repetition Frequency M02 of the Second Bezierzone Scanner 82 are set to an integer multiple of the repetition frequency M1 of the main resident scanner 83. [

The main resonant scanner 83 which oscillates at the repetition frequency M1 disperses the pulsed laser beam LB oscillated at the repetition frequency M to the (M / M1) X co-ordinates. In this embodiment, the repetition frequency M of the pulse laser beam LB oscillated by the pulsed laser beam oscillation means 51 is set to 40 kHz and the repetition frequency M1 of the main resonant scanner 83 is set to 10 kHz The main Resonant scanner 83 is dispersed every (1/4) x (1/10 k) seconds in the X coordinate of 4 (40/10). The spacing of the four X coordinates distributed by the main Resonant scanner 83 is set so as to correspond to the interval of the X coordinate of the bonding pad formed on the device of the semiconductor wafer, which will be described later, in the present embodiment .

The X-coordinate spreading means 8 in the embodiment shown in Fig. 5 is constructed as described above. The pulse laser beam LB emitted from the Y-coordinate spreading means 7 is transmitted to the first boresignal scanner 81 The reflection mirror 811 of FIG. First pulse laser beam LB incident on the reflection mirror 811 of the resonant scanner 81 is reflected by the reflection mirror 821 of the second borequitent scanner 82 and the reflected laser beam LB of the main resonant scanner 83 And is emitted via a reflection mirror 831. [

6 shows the relationship between the repetition frequency M01 (30 kHz) of the first boresignal scanner 81, the repetition frequency M02 (20 kHz) of the second boresignal scanner 82, There is shown a graph showing a repetition frequency M 1 (10 kHz) and a summation repetition frequency MX obtained by summing each repetition frequency M 01 (30 kHz), M 02 (20 kHz) and M 1 (10 kHz). In Fig. 6, the horizontal axis represents time (1/10 k) seconds, and the vertical axis represents the X coordinate. The pulsed laser beam LB emitted from the pulsed laser beam oscillation means 51 is added from the reflection mirror 831 of the main resonant scanner 83 every (1/4) x (1/10 k) Four (I Ⅱ Ⅲ Ⅳ) are emitted at the X coordinate corresponding to the summation repetition frequency MX. The X coordinate of the four pulsed laser beams LB outputted from the reflection mirror 831 of the main resonant scanner 83 is obtained by multiplying the repetition frequency M1 of the main resonant scanner 83 (30 kHz) of the first borequencer scanner 81 and the phase of the repetition frequency M02 (20 kHz) of the second borequiten scanner 82 are shifted from each other.

The pulse dispersing means 6 composed of the Y coordinate dispersing means 7 and the X coordinate dispersing means 8 described above is constituted as described above and the pulsed laser beam LB oscillated from the pulsed laser beam emitting means 51, (I, II, III, IV) to the XY coordinates shown in FIG. 7 every (1/10 k) seconds via the optical path deflecting means 9 and the condenser 52.

Returning to Fig. 2 and continuing with the description, the optical path deflecting means 9 is composed of a galvanometer scanner 91 in the present embodiment. Axis direction from the position indicated by the solid line to the position indicated by the broken line by displacing the galvanometer scanner 91 from the position indicated by the solid line to the position indicated by the broken line so that the condenser lens 521 ). 2) of the chuck table 36 by synchronizing the displacement speed from the position indicated by the solid line of the galvanometer scanner 91 to the position indicated by the broken line with the moving speed of the chuck table 36 in the leftward direction in Fig. The pulsed laser beam can be irradiated continuously to the irradiating position indicated by the solid line and the broken line in the embodiment shown in Fig. 2 while being processed and fed to the left.

The laser machining apparatus 1 according to the present embodiment includes the control means 10 shown in Fig. The control means 10 is constituted by a computer and includes a central processing unit (CPU) 101 for performing arithmetic processing according to a control program, a read only memory (ROM) 102 for storing a control program and the like, A random access memory (RAM) 103 for storing a random access memory (RAM) 103, and an input interface 104 and an output interface 105. Detection signals from the X-axis direction position detection means 374, the Y-axis direction position detection means 384, the image pickup means 50, and the like are input to the input interface 104 of the control means 10. The X-axis direction moving means 37, the Y-axis direction moving means 38 and the pulsed laser beam emitting means 51 of the laser beam irradiating means 5 are provided from the output interface 105 of the control means 10, A frequency setting device 712 for setting the frequency of the first borequiten scanner 71 constituting the Y coordinate dispersion means 7 of the pulse dispersion means 6, A frequency setter 722 for setting the frequency of the main resonant scanner 73, a frequency setter 732 for setting the frequency of the main resonant scanner 73, a first beam constituting the X-coordinate dispersing means 8 of the pulse dispersing means 6, A frequency setting unit 812 for setting the frequency of the resident scanner 81, a frequency setting unit 822 for setting the frequency of the second bored zone scanner 82, a frequency setting unit for setting the frequency of the main resident scanner 83 A galvanometer scanner 91 as an optical path deflecting means 9, and the like And outputs a control signal.

The laser machining apparatus 1 in this embodiment is configured as described above, and its operation will be described below. 9 shows a perspective view of the semiconductor wafer 20 as a workpiece processed by the laser machining apparatus 1 described above. The semiconductor wafer 20 shown in Fig. 9 is made up of a silicon wafer, and a plurality of lines 201 to be divided are formed in a lattice pattern on the surface 20a, and a plurality of lines 201 to be divided A device 202 such as an IC or an LSI is formed in a plurality of areas defined by the areas. Each of these devices 202 has the same configuration. Four bonding pads 203 are formed on the surface of the device 202, respectively. These four bonding pads 203 are formed of copper in the present embodiment. Via holes reaching the bonding pads 203 from the back surface 20b are formed at positions corresponding to the four bonding pads 203, respectively. The coordinates of the four bonding pads 203 in each device 202 are stored in the random access memory (RAM) 103 with design value data. The pulse dispersing means (not shown) of the present embodiment includes the Y coordinate dispersing means 7 and the X coordinate dispersing means 8 in correspondence with the coordinates of the four bonding pads 203 in the device 202 6) sets the XY coordinates of the four (I, II, III) pulsed laser beams to be emitted.

10, in order to form the through-holes from the back surface 20b to the respective bonding pads at positions corresponding to the four bonding pads 203 of the semiconductor wafer 20 described above, an annular frame F The surface 20a of the semiconductor wafer 20 is attached to the surface of the adhesive tape T on which the outer peripheral portion is mounted so as to cover the inner opening of the semiconductor wafer 20. Further, the adhesive tape T is formed of a vinyl chloride (PVC) sheet in the present embodiment.

The adhesive tape T side of the semiconductor wafer 20 is placed on the chuck table 36 of the laser processing apparatus 1 shown in Fig. Then, the semiconductor wafer 20 is sucked and held on the chuck table 36 via the adhesive tape T by operating the suction means (not shown) (workpiece holding step). Therefore, the back surface 20b of the semiconductor wafer 20 held on the chuck table 36 via the adhesive tape T is the upper side. The annular frame F supported by the adhesive tape T on the semiconductor wafer 20 is fixed by a clamp 362 formed on the chuck table 36. [

The chuck table 36 in which the semiconductor wafer 20 is sucked and held is positioned immediately below the imaging means 50 by operating the X axis direction moving means 37. [ When the chuck table 36 is positioned immediately below the imaging means 50, an alignment operation for detecting the machining area of the semiconductor wafer 20 to be laser-processed is executed by the imaging means 50 and the control means 10 do. That is, the image pickup means 50 and the control means 10 are arranged so that the laser beam irradiating means 5 for irradiating the laser beam along the line 201 to be divided, which is formed in the first direction of the semiconductor wafer 20, The image processing such as pattern matching for aligning with the laser beam irradiation position is performed, and alignment of the laser beam irradiation position is performed. At this time, the surface 20a on which the line to be divided 201 of the semiconductor wafer 20 is formed is located on the lower side. However, as described above, the imaging means 50 is provided with the infrared illumination means and the optical system (Infrared ray CCD) for outputting an electric signal corresponding to the infrared rays, it is possible to pick up the line to be divided 201 viewed from the back surface 20b.

11, if the chuck table 36 is moved to the position where the chuck table 36 is located, the chuck table 36 is moved to the position where the chuck table 36 is located, To the laser beam irradiation area where the condenser 52 of the laser beam irradiating means 5 is located and to set the intermediate position of the device 202 between the predetermined line to be divided 201 and the line to be divided 201, (52). Then, the light-converging point of the pulsed laser beam irradiated from the condenser 52 is positioned near the back surface (upper surface) of the semiconductor wafer 20. The pulse laser beam emitting means 51 of the laser beam irradiating means 5 and the galvanometer scanner 91 as the pulse dispersing means 6 and the optical path deflecting means 9 are operated and the X axis direction moving means 37 Is operated to move the chuck table 36 at a predetermined moving speed in the direction indicated by the arrow X1 in Fig.

The XY coordinates of the four (I, II, III, IV) pulsed laser beams emitted from the pulse dispersing means 6 composed of the Y coordinate dispersing means 7 and the X coordinate dispersing means 8 are formed on the semiconductor wafer 20 The pulse laser beam emitted from the pulsed laser beam oscillation means 51 at a position corresponding to the four bonding pads 203 is set in correspondence with the coordinates of the four bonding pads 203 in the device 202. Therefore, . Then, while the chuck table 36 is moved by a predetermined amount, the galvanometer scanner 91 operates as described above, so that a predetermined number of pulse laser beams are irradiated to positions corresponding to the four bonding pads 203 And through holes reaching the four bonding pads 203 are formed on the semiconductor wafer 20. In this manner, a laser machining process is performed to form through holes at positions corresponding to the four bonding pads 203 formed in all the devices 202 formed in the same row in the X-axis direction. This laser processing step is performed at positions corresponding to the four bonding pads 203 formed in all the devices 202 formed on the semiconductor wafer 20. [

The laser processing step is carried out under the following processing conditions.

Light source: YVO4 pulse laser or YAG pulse laser

Wavelength: 355 nm

Repetition frequency: 40 kHz

Average power: 4 W

Condensing spot diameter: φ10 μm

Processing feed rate: 100 mm / sec

No. 1 Repetition frequency of the Resonant scanner: 30 kHz

Part 2 Repetition frequency of the resonant scanner: 20 kHz

Repetition frequency of main resonant scanner: 10 kHz

As described above, in the laser machining apparatus 1 according to the above-described embodiment, the X coordinate corresponding to the coordinates of the plurality of bonding pads 203 formed on the device 202 formed on the semiconductor wafer 20, Y It is possible to simultaneously irradiate pulsed laser beams to a plurality of coordinates at the maximum repetition frequency (10 kHz) that does not cause cracks when the through holes are formed at the coordinate positions, thereby improving the productivity.

2: Stop expectation
3: chuck table mechanism
36: Chuck table
37: X-axis direction moving means
38: Y-axis direction moving means
4: laser beam irradiation unit
5: laser beam irradiation means
51: Pulsed laser beam emitting means
52: Concentrator
6: Pulse dispersion means
7: Y coordinate dispersion means
71: Part 1 Resonant Scanner
72: Part 2 Resonant Scanner
73: Primary Resonant Scanner
8: X coordinate distribution means
81: Part 1 Resonant Scanners
82: Part 2 Resonant Scanner
83: Primary Resonant Scanner
9: optical path deflection means
10: Control means
20: Semiconductor wafer

Claims (2)

A laser processing apparatus comprising:
A chuck table for holding the workpiece in an XY plane,
And a laser beam irradiating means for irradiating the workpiece held on the chuck table with a laser beam,
Wherein the laser beam irradiation means comprises pulse laser beam oscillation means for oscillating a pulsed laser beam at a repetition frequency M,
A condenser for condensing the pulsed laser beam oscillated by the pulsed laser beam oscillation means and irradiating the workpiece held on the chuck table,
And pulse dispersing means disposed between the pulsed laser beam emitting means and the condenser and for dispersing the pulsed laser beam to a plurality of X coordinates and a plurality of Y coordinates,
Wherein the pulse dispersing means includes a mirror for reflecting the pulsed laser light oscillated at the repetition frequency M and having a mirror for oscillating at a repetition frequency M1 lower than the repetition frequency M to disperse the pulsed laser light in the (M / M1) And a laser processing unit for processing the laser beam. The method according to claim 1,
Wherein the pulse dispersing means includes Y coordinate dispersing means for dispersing the pulsed laser beam in a plurality of Y coordinates and X coordinate dispersing means for dispersing the pulse laser light in a plurality of X coordinates,
The Y coordinate distribution means includes a first main scanner that oscillates at the repetition frequency M1 and a first compensator that oscillates at a repetition frequency that is an integral multiple of the repetition frequency M1 to disperse the pulsed laser beam, The Y coordinate at which the pulse laser beam is irradiated is specified by shifting the phase of the repetition frequency of the main scanner and the first beam scanner,
The X coordinate spreading means includes a second main scanner for oscillating at the repetition frequency M1 and a second compensator for oscillating at a repetition frequency of an integral multiple of the repetition frequency M1 to disperse the pulsed laser beam, And the X-coordinate to which the pulse laser beam is irradiated is specified by shifting the phase of the repetition frequency of the main scanner and the second beam scanner.

Images