TWI660804B - Laser processing device - Google Patents

Abstract

Provided is a laser processing apparatus capable of simultaneously forming holes in a plurality of positions without causing cracks.

The laser processing device includes: a chuck platform that holds the workpiece on the XY plane; and a laser light irradiation means that irradiates laser light on the workpiece that is held on the chuck platform; : Pulse laser light oscillation means to oscillate the pulse laser light at repeated frequency M; and a condenser to condense the pulsed laser light oscillated by the pulse laser light oscillation means and irradiate it to the chuck to be held The processed object of the platform; and the pulse dispersing means, which is arranged between the pulse laser ray oscillating means and the condenser, and disperses the pulse laser ray to a plurality of X coordinates and a plurality of Y coordinates; the pulse dispersing means is provided with a scanner It has a mirror that reflects the pulsed laser light oscillating at the repeated frequency M and shakes at a repeated frequency M1 lower than the repeated frequency M to disperse the pulsed laser light to (M / M1) coordinates.

Description

Laser processing device

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, the surface of the semiconductor wafer having a substantially circular plate shape is divided into a plurality of regions by a predetermined division line arranged in a grid shape, and devices such as ICs and LSIs are formed in the separated regions. Then, the semiconductor wafer is cut along a predetermined division line, whereby the area where the device is formed is divided to manufacture each semiconductor device wafer.

In order to achieve miniaturization and high functionality of the device, a module structure in which a plurality of semiconductor wafers are laminated and electrodes of the laminated plurality of semiconductor devices are connected is being put into practical use. The module structure is configured to irradiate laser light from a back surface corresponding to a place where an electrode is formed in a semiconductor wafer to form a through hole in which an electrode is buried, and embed copper or aluminum connected to the electrode in the through hole. And other conductive materials (for example, Patent Document 1).

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-62261

However, in order to form a through-hole by laser processing as described above, it is necessary to irradiate a plurality of pulsed laser rays to the same place (through-hole penetration position). Therefore, it is desirable to increase the repetition frequency of the pulsed laser rays to achieve productivity Promotion.

However, if a plurality of pulsed laser beams are irradiated to the same place at a high repetition frequency, thermal accumulation cracks may occur, and there is a problem that the quality of the device is reduced.

According to the experiments of the inventor, it is known that the maximum repetition frequency that does not cause cracks when forming a through hole is 10 kHz.

The present invention has been developed in view of the above-mentioned facts, and a main technical problem thereof is to provide a laser processing device capable of simultaneously forming through-holes at a plurality of positions without causing cracks.

In order to solve the above-mentioned main technical problems, according to the present invention, a laser processing device is provided, which includes: a chuck platform that holds a workpiece on an XY plane; and a laser light irradiation means for holding the chuck platform. The processed object irradiates laser light; the laser light irradiating means, including Including: pulsed laser light oscillation means, which oscillates the pulsed laser light at the repeated frequency M; a condenser, which condenses and irradiates the pulsed laser light which is oscillated by the pulsed laser light oscillation means to be held in the The processed object of the chuck platform; and a pulse dispersing means arranged between the pulse laser ray oscillating means and the concentrator, and dispersing the pulse laser ray to a plurality of X coordinates and a plurality of Y coordinates; the pulse The dispersing means includes a scanner having a mirror for reflecting the pulsed laser light oscillating at the repeated frequency M, and shaking at a repeated frequency M1 lower than the repeated frequency M to disperse the pulsed laser light to (M / M1 ) Coordinates.

Preferably, the pulse dispersing means includes a Y-coordinate dispersing means for dispersing pulsed laser light to a plurality of Y-coordinates and an X-coordinate dispersing means for dispersing to a plurality of X-coordinates, The Y-coordinate dispersing means includes a first main scanner that is shaken at an iterative frequency M1 and a first auxiliary scanner that is shaken at an iterative frequency that is an integer multiple of the iterative frequency M1 to disperse pulsed laser light, so that the first main scanner The phase of the repeated frequencies of the scanner and the first auxiliary scanner is staggered to identify the Y coordinate of the pulsed laser light, The X-coordinate dispersion means is provided with a second main scanner that is shaken at an iterative frequency M1 and a second auxiliary scanner that is shaken at an iterative frequency that is an integer multiple of the iterative frequency M1 to disperse pulsed laser light, so that the second main scanner The phase of the repeated frequencies of the scanner and the second auxiliary scanner is shifted to identify the X-coordinate that is illuminated by the pulsed laser light.

According to the laser processing device of the present invention, a laser light irradiation means for irradiating laser light on a workpiece held on a chuck table held in an XY plane is provided with a pulse laser light oscillation means at an iterative frequency M Oscillating pulsed laser light; a condenser that condenses and irradiates the pulsed laser light oscillated by the pulsed laser light oscillating means and irradiates the workpiece held by the workpiece holding means; and pulse dispersing means Is arranged between the pulse laser ray oscillating means and the condenser to disperse the pulse laser ray to a plurality of X-coordinates and a plurality of Y-coordinates; the pulse dispersing means is provided with a scanner, which has a The pulse laser light is reflected by a mirror that shakes at a repetition frequency M1 lower than the repetition frequency M to disperse the pulse laser light to (M / M1) coordinates, so it should correspond to the coordinates set on the workpiece When a through hole is formed at the X coordinate and the Y coordinate, a plurality of coordinates can be simultaneously irradiated with pulsed laser light at the maximum repetition frequency without causing cracks, and the productivity will be improved.

2‧‧‧ static abutment

3‧‧‧ Chuck platform mechanism

36‧‧‧Chuck platform

37‧‧‧X-axis direction moving means

38‧‧‧Y-axis direction moving means

4‧‧‧laser light irradiation unit

5‧‧‧Laser light irradiation means

51‧‧‧Pulse laser light oscillation means

52‧‧‧Condenser

6‧‧‧ Pulse Dispersion Means

7‧‧‧Y Coordinate Dispersion Means

71‧‧‧1st auxiliary resonance scanner

72‧‧‧ 2nd auxiliary resonance scanner

73‧‧‧main resonance scanner

8‧‧‧X coordinate dispersion method

81‧‧‧1st auxiliary resonance scanner

82‧‧‧Second auxiliary resonance scanner

83‧‧‧Main resonance scanner

9‧‧‧ light path deflection

10‧‧‧Control

20‧‧‧Semiconductor wafer

[Fig. 1] A perspective view of a laser processing apparatus according to an embodiment of the present invention.

[Fig. 2] A block configuration diagram of a laser light irradiation means provided in the laser processing apparatus shown in Fig. 1. [Fig.

[Fig. 3] A schematic block diagram of the Y-coordinate dispersion means constituting the laser light irradiation means shown in Fig. 2. [Fig.

[Fig. 4] The iterative frequency M01 (30kHz) of the first auxiliary resonance scanner and the second auxiliary resonance scanner constituting the Y-coordinate dispersion means shown in Fig. 3 Schematic diagram of the iterative frequency M02 (20kHz), the iterative frequency M1 (10kHz) of the main resonance scanner, and the total iterative frequency MY obtained by summing each of the iterative frequencies M01 (30kHz), M02 (20kHz), and M1 (10kHz).

[Fig. 5] A schematic block diagram of the X-coordinate dispersion means constituting the laser light irradiation means shown in Fig. 2. [Fig.

[Fig. 6] The iterative frequency M01 (30kHz) of the first auxiliary resonance scanner and the iterative frequency M02 (20kHz) of the second auxiliary resonance scanner constituting the X-coordinate dispersion means shown in Fig. 5 and the iteration of the main resonance scanner Schematic diagram of frequency M1 (10kHz) and total iterative frequency MX obtained by summing each iterative frequency M01 (30kHz), M02 (20kHz) and M1 (10kHz).

[Fig. 7] By means of a pulse dispersing means composed of the Y-coordinate dispersing means shown in Fig. 3 and the X-coordinate dispersing means shown in Fig. 5, the coordinates of the pulsed laser light oscillated from the pulsed laser light oscillating means are exemplified. Illustration.

[Fig. 8] A block configuration diagram of control means provided in the laser processing apparatus shown in Fig. 1. [Fig.

[FIG. 9] A perspective view of a semiconductor wafer as a workpiece.

[Fig. 10] A schematic perspective view of a state where the semiconductor wafer shown in Fig. 9 is attached to an adhesive tape mounted on a ring frame.

[Fig. 11] An explanatory diagram of a laser processing process performed by the laser processing apparatus shown in Fig. 1. [Fig.

Hereinafter, a preferred embodiment of a laser processing apparatus constructed in accordance with the present invention will be described in detail with reference to the attached drawings.

FIG. 1 illustrates a perspective view of a laser processing apparatus 1 according to an embodiment of the present invention. The laser processing apparatus 1 shown in FIG. 1 includes: a stationary base 2; and a chuck table mechanism 3, which is arranged on the stationary base 2 and can be oriented toward the processing feed direction indicated by arrow X, that is, X It moves in the axial direction and holds the workpiece; and a laser light irradiation unit 4 is arranged on the base 2 as a laser light irradiation means.

The chuck platform mechanism 3 includes: a pair of guide rails 31 and 31 arranged on the stationary base 2 in parallel along the X-axis direction; and a first sliding block 32 arranged on the guide rails 31 and 31 so as to face the X Axis direction movement; and a second slide block 33 disposed on the first slide block 32 so as to be able to move in an indexing feeding direction indicated by an arrow Y orthogonal to the X-axis direction, that is, the Y-axis direction; and The support platform 35 is supported by the cylindrical member 34 on the second sliding block 33, and the chuck platform 36 is a workpiece holding means for holding the workpiece on the XY plane. The chuck platform 36 is provided with an adsorption chuck 361 formed of a porous material, and an upper surface of the adsorption chuck 361, that is, a holding surface, sucks a processed object, for example, a circular semiconductor wafer by suction (not shown). Means to keep it. The chuck platform 36 configured as described above is rotated by a pulse motor (not shown) arranged in the cylindrical member 34. The chuck platform 36 is provided with a clamp 362 for fixing an annular frame that supports a workpiece such as a semiconductor wafer through a protective tape.

The first sliding block 32 is provided below the first sliding block 32 with the first sliding block 32. A pair of guide grooves 321 and 321 are fitted to the guide rails 31 and 31, and a pair of guide rails 322 and 322 are formed on the guide grooves 321 and 321 in parallel along the Y-axis direction. The first slide block 32 configured as described above is configured to be movable in the X-axis direction along the pair of guide rails 31 and 31 by being fitted to the pair of guide rails 31 and 31 by the guided grooves 321 and 321. The chuck platform mechanism 3 in the present embodiment includes an X-axis direction moving means 37 for moving the first slider 32 along the pair of guide rails 31 and 31 in the X-axis direction. The X-axis direction moving means 37 includes a male screw 371 disposed in parallel between the pair of guide rails 31 and 31, and a driving source such as a pulse motor 372 for rotating and driving the male screw 371. One end of the male screw 371 is rotatably supported by a bearing block 373 fixed to the stationary base 2, and the other end is drivingly connected to the output shaft of the pulse motor 372. In addition, the male screw 371 is screw-engaged with a through female screw hole formed on a female screw block (not shown) protrudingly provided on the lower surface of the central portion of the first slide block 32. Therefore, the male screw 371 is driven forward and reverse by the pulse motor 372, so that the first slide block 32 is moved along the guide rails 31 and 31 in the X-axis direction.

The laser processing apparatus 1 includes an X-axis direction position detection means 374 for detecting the X-axis position of the chuck table 36. The position detection means 374 in the X-axis direction is read by a linear scale 374a provided along the guide rail 31 and a first slide block 32 that moves along the linear scale 374a together with the first slide block 32. It consists of a head 374b. In the present embodiment, the read head 374b of the X-axis direction position detection means 374 sends a pulse signal of one pulse every 1 μm to a control means described later. Then, the control means described later counts the input pulse signal. No., thereby detecting the X-axis position of the chuck platform 36. When the pulse motor 372 is used as the drive source of the processing feed means 37, the drive pulses of the control means described later are output to the pulse motor 372, and the X-axis direction of the chuck table 36 can also be detected. position. In addition, 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 that detects the rotation number of the servo motor is sent to a control means described later, and the control means counts the input The pulse signal can also detect the position in the X-axis direction of the chuck table 36.

The second sliding block 33 is provided with a pair of guided grooves 331 and 331 fitted on the lower surface of the second sliding block 33 and fitted with a pair of guide rails 322 and 322 provided on the upper surface of the first sliding block 32. The grooves 331 and 331 are fitted to the pair of guide rails 322 and 322 and are configured to be movable in the Y-axis direction. The chuck platform mechanism 3 is provided with a Y-axis direction moving means 38 for moving the second slider 33 along the pair of guide rails 322 and 322 provided on the first slider 32 in the Y-axis direction. The Y-axis direction moving means 38 includes a male screw 381 disposed in parallel between the pair of guide rails 322 and 322 and a driving source such as a pulse motor 382 for rotating and driving the male screw 381. One end of the male screw 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 drivingly connected to the output shaft of the pulse motor 382. In addition, the male screw 381 is screw-engaged with a through female screw hole formed on a female screw block (not shown) protrudingly provided on the lower surface of the central portion of the second slide block 33. Therefore, the male screw 381 is driven forward and reverse by the pulse motor 382, so that the second sliding block 33 is guided along the guide rails 322, 322. Move in the Y-axis direction.

The laser processing apparatus 1 includes a Y-axis direction position detection means 384 for detecting the Y-axis direction position of the second slider 33. The position detection means 384 in the Y-axis direction is composed of a linear scale 384a arranged along the guide rail 322 and a reading head 384b arranged on the second slide block 33 and moving along the linear scale 384a together with the second slide block 33. Make up. In this embodiment, the read head 384b of the Y-axis-direction position detecting means 384 sends a pulse signal of one pulse every 1 μm to a control means described later. Then, the control means described later counts the input pulse signals, thereby detecting the Y-axis position of the chuck table 36. In addition, when the pulse motor 382 is used as the driving source of the Y-axis direction moving means 38, the drive pulses of the control means described later after the drive signal is output to the pulse motor 382 are counted, whereby the Y of the chuck table 36 can also be detected. Axis direction position. In addition, 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 that detects the rotation number of the servo motor is sent to a control means described later, and the control means counts the input The pulse signal can also detect the position in the Y-axis direction of the chuck table 36.

The laser light irradiation unit 4 includes: a support member 41 disposed on the base 2; and a housing 42 supported by the support member 41 to extend substantially horizontally; and a laser light irradiation means 5 disposed. The casing 42 and the photographing means 50 are disposed at the front end of the casing 42 to detect a processing area where laser processing should be performed. In addition, the imaging means 50 includes an illumination means for illuminating the workpiece, and capturing the illumination received by the illumination means. The optical system in the area and the imaging element (CCD) that captures the image captured by the optical system, etc., and sends the captured image signal to the control means described later.

The laser light irradiation means 5 will be described with reference to FIG. 2. As shown in FIG. 2, the laser light irradiation means 5 includes a pulse laser light oscillation means 51 and a condenser 52 that condenses the pulse laser light oscillated from the pulse laser light oscillation means 51 and The workpiece W irradiated to the chuck platform 36 is irradiated; and the pulse dispersing means 6 is arranged between the pulse laser light oscillating means 51 and the condenser 52, and the laser beam oscillating from the pulse laser light oscillating means 51 is oscillated. The pulsed laser light is scattered to a plurality of Y and X coordinates; and the optical path deflection means 9 deflects the pulsed laser light scattered by the pulse dispersing means 6 toward the X-axis direction. The pulse laser light oscillating means 51 is composed of a pulse laser oscillator 511 and an iterative frequency setting means 512 attached thereto. The pulse laser oscillator 511 of the pulse laser light oscillating means 51 is a pulse laser light LB having an oscillation wavelength of 355 nm in this embodiment. The repeated frequency M of the pulsed laser beam LB oscillated by the pulsed laser beam oscillating means 51 is set to 40 kHz in this embodiment. The condenser 52 includes a condenser lens 521 composed of an fθ lens, and is guided by the pulse laser light oscillating means 51 and transmitted through the Y-coordinate dispersing means 7 and X-coordinate dispersing means 8 and the optical path deflection means 9. The pulsed laser light LB is focused.

The pulse dispersing means 6 disposed between the above-mentioned pulse laser ray oscillating means 51 and the condenser 52, in this embodiment, The pulsed laser ray LB oscillated by the pulsed laser ray oscillating means 51 is dispersed to a plurality of Y-coordinate dispersion means 7, and the pulsed laser ray LB dispersed to the Y-coordinate by the Y-coordinate dispersion means 7 is dispersed to The X-coordinate dispersion means 8 of a plurality of X-coordinates is constituted. The Y coordinate dispersing means 7, as shown in FIG. 3, includes: a first auxiliary resonance scanner 71 provided with a reflecting mirror 711; and a second auxiliary resonance scanner 72 provided with a reflecting mirror 721; and a main resonance scanner 73, Reflector 731 is available.

The system is configured such that the first auxiliary resonance scanner 71 is shaken in response to the repeated frequency set by the frequency setter 712, and the second auxiliary resonance scanner 72 is shaken in response to the repeated frequency set by the frequency setter 722, and the main resonance scan The device 73 is shaken in response to the repeated frequency set by the frequency setter 732. The frequency setter 712 sets the repeated frequency M01 of the first auxiliary resonance scanner 71 to 30 kHz, the frequency setter 722 sets the repeated frequency M02 of the second auxiliary resonance scanner 72 to 20 kHz, and the frequency setter 732 sets the main resonance scanner 73 The repeated frequency M1 is set to 10kHz. The repeated frequency M01 of the first auxiliary resonance scanner 71 and the repeated frequency M02 of the second auxiliary resonance scanner 72 are set to an integer multiple of the repeated frequency M1 of the main resonance scanner 73.

The main resonance scanner 73 shaken at the above-mentioned repeated frequency M1 is to disperse the pulsed laser light LB oscillated by the pulsed laser light oscillating means 51 at the repeated frequency M to (M / M1) Y-coordinates. In this embodiment, the repetition frequency M of the pulsed laser beam LB oscillated by the pulse laser ray oscillation means 51 is set to 40 kHz, and the repetition frequency M1 of the main resonance scanner 73 is set to 10 kHz. Therefore, the main resonance scanner 73 (1/4) × (1 / 10k) seconds are scattered to 4 (40/10) Y coordinates. In addition, in this embodiment, the intervals of the four Y-coordinates dispersed by the main resonance scanner 73 are set to correspond to the intervals of the Y-coordinates of the pads provided on a semiconductor wafer, which is a to-be-processed object. .

The Y-coordinate dispersion means 7 is configured as described above, and the pulsed laser beam LB oscillated from the pulsed laser beam oscillating means 51 enters the mirror 711 of the first auxiliary resonance scanner 71. The pulsed laser light LB incident on the mirror 711 of the first auxiliary resonance scanner 71 passes through the mirror 721 of the second auxiliary resonance scanner 72 and the mirror 731 of the main resonance scanner 73 and is emitted.

FIG. 4 discloses the iterative frequency M01 (30 kHz) of the first auxiliary resonance scanner 71, the iterative frequency M02 (20 kHz) of the second auxiliary resonance scanner 72, and the iterative frequency M1 (10 kHz) of the main resonance scanner 73, and Schematic diagram of the total iterative frequency MY obtained by summing each of the iterative frequencies M01 (30 kHz), M02 (20 kHz), and M1 (10 kHz). In FIG. 4, the horizontal axis represents time (1 / 10k) seconds, and the vertical axis represents the Y coordinate. The pulsed laser light LB oscillated from the pulsed laser light oscillating means 51 described above emits four (I II III) from the mirror 731 of the main resonance scanner 73 every (1/4) × (1 / 10k) seconds. IV) The Y coordinate corresponding to the total iterative frequency MY which is the total.

In addition, the four (I II III IV) Y coordinates of the pulsed laser beam LB emitted from the mirror 731 of the main resonance scanner 73 can be obtained by setting the repeated frequency M1 (10 kHz) of the main resonance scanner 73 and the first Repeated frequency M01 (30kHz) of auxiliary resonance scanner 71 and second auxiliary resonance scanner The phase of the iterative frequency M02 (20kHz) of 72 is staggered and discerned.

Next, the X-coordinate dispersion means 8 constituting the pulse dispersion means 6 will be described with reference to FIG. 5. The X-coordinate dispersing means 8 is configured in this embodiment so that the Y-coordinate dispersing means 7 rotates 90 degrees with the optical path of the laser beam LB emitted from the pulse laser beam oscillating means 51 as a rotation axis. It is provided with: a first auxiliary resonance scanner 81 provided with a reflecting mirror 811; a second auxiliary resonance scanner 82 provided with a reflecting mirror 821; and a main resonance scanner 83 provided with a reflecting mirror 831.

The system is configured such that the first auxiliary resonance scanner 81 is shaken in response to the repeated frequency set by the frequency setter 812, and the second auxiliary resonance scanner 82 is shaken in response to the repeated frequency set by the frequency setter 822, and the main resonance scan The device 83 is shaken in response to the repeated frequency set by the frequency setter 832. The frequency setter 812 sets the repeated frequency M01 of the first auxiliary resonance scanner 81 to 30 kHz, the frequency setter 822 sets the repeated frequency M02 of the second auxiliary resonance scanner 82 to 20 kHz, and the frequency setter 832 sets the main resonance scanner 83 The repeated frequency M1 is set to 10kHz. The repeated frequency M01 of the first auxiliary resonance scanner 81 and the repeated frequency M02 of the second auxiliary resonance scanner 82 are set to an integer multiple of the repeated frequency M1 of the main resonance scanner 83.

The main resonance scanner 83 shaken at the above-mentioned repeated frequency M1 is to disperse the pulsed laser light LB oscillated by the pulsed laser light oscillating means 51 at the repeated frequency M to (M / M1) X-coordinates. In this embodiment, the repetition frequency M of the pulsed laser beam LB oscillated by the pulsed laser beam oscillating means 51 is set to 40 kHz. The iterative frequency M1 is set to 10 kHz, so the main resonance scanner 83 is scattered to 4 (40/10) X coordinates every (1/4) × (1 / 10k) seconds. In addition, in this embodiment, the intervals of the four X-coordinates dispersed by the main resonance scanner 83 are set to correspond to the intervals of the X-coordinates of the pads provided on a semiconductor wafer, which is a to-be-processed object. .

The X-coordinate dispersion means 8 in the embodiment shown in FIG. 5 is configured as described above, and the pulsed laser light LB emitted from the Y-coordinate dispersion means 7 enters the mirror 811 of the first auxiliary resonance scanner 81. The pulsed laser light LB incident on the mirror 811 of the first auxiliary resonance scanner 81 passes through the mirror 821 of the second auxiliary resonance scanner 82 and the mirror 831 of the main resonance scanner 83 and is emitted.

FIG. 6 shows the iterative frequency M01 (30 kHz) of the first auxiliary resonance scanner 81, the iterative frequency M02 (20 kHz) of the second auxiliary resonance scanner 82, and the iterative frequency M1 (10 kHz) of the main resonance scanner 83, and Schematic diagram of the total iterative frequency MX obtained by summing each iterative frequency M01 (30kHz), M02 (20kHz), and M1 (10kHz). In FIG. 6, the horizontal axis represents time (1 / 10k) seconds, and the vertical axis represents the X coordinate. Four pulsed laser beams LB oscillated from the pulsed laser beam oscillating means 51 are emitted from the mirror 831 of the main resonance scanner 83 at intervals of (1/4) × (1 / 10k) seconds (I II III IV ) To the X coordinate corresponding to the total iterative frequency MX and the total.

In addition, the four (I II III IV) X coordinates of the pulsed laser beam LB emitted from the mirror 831 of the main resonance scanner 83 can be obtained by setting the repeated frequency M1 (10 kHz) of the main resonance scanner 83 and the first Auxiliary resonance scan The phases of the repeated frequency M01 (30 kHz) of the scanner 81 and the repeated frequency M02 (20 kHz) of the second auxiliary resonance scanner 82 are staggered and distinguished.

The pulse dispersing means 6 composed of the Y-coordinate dispersing means 7 and the X-coordinate dispersing means 8 is configured as described above, and the pulse laser beam LB oscillated from the pulse laser ray oscillating means 51 passes through the optical path deflection means 9 and condenses The optical device 52 irradiates 4 (I II III IV) to the XY coordinates shown in FIG. 7 every (1 / 10k) seconds.

Returning to FIG. 2 to continue the description, the optical path deflection means 9 is constituted by a galvano scanner 91 in this embodiment. The galvanometer scanner 91 is shifted from the position shown by the solid line to the position shown by the dotted line, thereby directing the pulsed laser light from the position shown by the solid line in the X-axis direction to the position shown by the dotted line to guide the condenser. 52's condenser lens 521. Therefore, by synchronizing the displacement speed from the position shown by the solid line to the position shown by the dotted line of the galvanometer scanner 91 and the moving speed of the chuck platform 36 to the left in FIG. In the state where the platform 36 is processed and fed to the left in FIG. 2, pulse laser light is continuously irradiated to the irradiation positions shown by the solid line and the broken line in the embodiment shown in FIG. 2.

The laser processing apparatus 1 in this embodiment includes a control means 10 shown in FIG. 8. The control means 10 is composed of a computer, and includes: a central processing device (CPU) 101 that performs calculation processing according to a control program; and a read-only memory (ROM) 102 that stores control programs and the like; and a readable and writable memory that stores calculation results and the like A random access memory (RAM) 103; and an input interface 104 and an output interface 105. For the input interface 104 of the control means 10, the input from the X-axis position detection means 374, Detection signals of the Y-axis direction position detection means 384, the imaging means 50, and the like. In addition, from the output interface 105 of the control means 10, a control signal is output to the X-axis direction moving means 37, the Y-axis direction moving means 38, the pulse laser light oscillating means 51 of the laser light irradiating means 5, and the settings constitute the pulse dispersion The Y-coordinate dispersion means of means 6 means 712 of the frequency of the first auxiliary resonance scanner 71, the frequency setter 722 of the frequency of the second auxiliary resonance scanner 72, and the frequency of the frequency of the main resonance scanner 73 Setter 732, frequency setter 812 that sets the frequency of the first auxiliary resonance scanner 81 of the X-coordinate dispersion means 8 constituting the pulse dispersion means 6, frequency setter 822 that sets the frequency of the second auxiliary resonance scanner 82, and sets the main A frequency setter 832 of the frequency of the resonance scanner 83, a galvanometer scanner 91 as the optical path deflection means 9, and the like.

The laser processing apparatus 1 in this embodiment is configured as described above, and its operation will be described below. FIG. 9 shows a perspective view of a semiconductor wafer 20 as an object to be processed by the laser processing apparatus 1. The semiconductor wafer 20 shown in FIG. 9 is composed of a silicon wafer. A plurality of planned division lines 201 are formed in a grid pattern on the surface 20a, and a plurality of regions are separated by the plurality of planned division lines 201. A device 202 such as an IC or an LSI is formed. Each of these devices 202 has the same configuration. Four pads 203 are formed on the surface of the device 202, respectively. The four pads 203 are formed of copper in this embodiment. At the positions corresponding to the four pads 203, via holes are formed from the back surface 20b to the pads 203, respectively.

Coordinates of the four pads 203 in each device 202, and their design value data It is stored in the random access memory (RAM) 103 described above. In addition, in this embodiment, the pulse dispersing means 6 composed of the Y-coordinate dispersing means 7 and the X-coordinate dispersing means 8 is set to correspond to the coordinates of the four pads 203 in the device 202, and four (I II III IV) XY coordinates of the pulsed laser light.

In order to form through-holes from the back surface 20b to the respective pads at positions corresponding to the four pads 203 of the semiconductor wafer 20, as shown in FIG. 10, the surface 20a of the semiconductor wafer 20 is attached to the adhesive On the surface of the adhesive tape T, an outer peripheral portion of the adhesive tape T is assembled so as to cover an inner opening portion of the ring-shaped frame F. The adhesive tape T is formed of a polyvinyl chloride (PVC) sheet in this embodiment.

After implementing the above-mentioned object supporting project, as shown in FIG. 1, the adhesive tape T side of the semiconductor wafer 20 is placed on the chuck platform 36 of the laser processing apparatus 1. Then, a suction means (not shown) is activated, whereby the semiconductor wafer 20 is sucked and held on the chuck table 36 through the adhesive tape T (the object holding process). For this reason, the semiconductor wafer 20 held on the chuck table 36 through the adhesive tape T has its back surface 20b on the upper side. The ring-shaped frame F supporting the semiconductor wafer 20 via the adhesive tape T is fixed by a clamp 362 arranged on the chuck platform 36.

After the above-mentioned object holding process is performed, the X-axis direction moving means 37 is activated to position the chuck stage 36 holding and holding the semiconductor wafer 20 directly below the imaging means 50. Once the chuck platform 36 is positioned directly below the photographing means 50, a calibration operation is performed by the photographing means 50 and the control means 10 to detect that the semiconductor wafer 20 should be laser processed. Processing area. That is, the photographing means 50 and the control means 10 perform image processing such as pattern matching to irradiate the laser beam with a laser beam along a predetermined division line 201 formed in the first direction of the semiconductor wafer 20. The concentrator 52 of the laser light irradiation means 5 performs alignment to complete the calibration of the laser light irradiation position. At this time, although the surface 20a of the planned division line 201 of the semiconductor wafer 20 is located on the lower side, as described above, the imaging means 50 is provided with an infrared illumination means and an optical system that captures infrared rays, and outputs an electronic signal corresponding to the infrared rays. The imaging means including an imaging element (infrared CCD) can penetrate the back surface 20b to image the division line 201.

As described above, the predetermined division line of the semiconductor wafer 20 formed on the chuck table 36 is detected, and the laser light irradiation position is calibrated. As shown in FIG. 11, the chuck table 36 is moved to The laser light irradiation area where the condenser 52 of the laser light irradiation means 5 is located locates the intermediate position of the device 202 between the predetermined division line 201 and the predetermined division line 201 directly below the condenser 52 . Then, the light-condensing point of the pulsed laser light radiated from the condenser 52 is positioned near the back surface (upper surface) of the semiconductor wafer 20. The pulsed laser light oscillating means 51 and the pulse dispersing means 6 of the laser light irradiation means 5 and the galvanometer scanner 91 as the optical path deflection means 9 are activated, and the X-axis direction moving means 37 is activated so that the chuck platform 36 faces The direction indicated by arrow X1 in 11 moves at a predetermined moving speed.

Four (I II III IV) pulsed laser rays emitted from the pulse dispersion means 6 composed of the Y-coordinate dispersion means 7 and the X-coordinate dispersion means 8. The XY coordinates are set to correspond to the coordinates of the four pads 203 formed in the device 202 of the semiconductor wafer 20, so the pulsed laser light oscillated from the pulsed laser light oscillating means 51 will be irradiated to 4 Corresponding positions of the solder pads 203. Then, while the chuck platform 36 moves a predetermined amount, the galvanometer scanner 91 operates as described above, thereby irradiating the pulsed laser light with a predetermined number of pulses to positions corresponding to the four pads 203, respectively. On the semiconductor wafer 20, through-holes are formed which reach four pads 203. In this way, a laser processing process for forming a through hole is performed at a position corresponding to the four pads 203 provided on all the devices 202 formed in the same row in the X-axis direction. This laser processing process is performed at positions corresponding to the four pads 203 provided on all the devices 202 formed on the semiconductor wafer 20.

The above laser processing process is performed under the following processing conditions.

Light source: YVO4 pulse laser or YAG pulse laser

Wavelength: 355nm

Repeated frequency: 40kHz

Average output: 4W

Condensing spot diameter: Φ10μm

Processing feed speed: 100mm / s

Repeated frequency of the first auxiliary resonance scanner: 30kHz

Repeated frequency of the second auxiliary resonance scanner: 20kHz

Repeated frequency of the main resonance scanner: 10kHz

As described above, the laser processing apparatus 1 in the above embodiment When a through hole is formed in the X coordinate and Y coordinate position corresponding to the coordinates of a plurality of pads 203 provided on the device 202 formed on the semiconductor wafer 20, the maximum repetition frequency can be achieved without causing cracks ( 10kHz) Simultaneously irradiate pulse laser light to a plurality of coordinates, the productivity will be improved.

Claims (1)

A laser processing device, comprising: a chuck platform that holds a workpiece on an XY plane; and a laser light irradiation means for irradiating laser light on a workpiece that is held on the chuck platform; The laser light irradiation means includes a pulse laser light oscillation means to oscillate the pulse laser light at an iterative frequency M; and a condenser to condense the pulsed laser light oscillated by the pulse laser light oscillation means. And irradiate the workpiece to be held on the chuck platform; and a pulse dispersing means arranged between the pulse laser ray oscillating means and the condenser to disperse the pulse laser ray to a plurality of X coordinates and A plurality of Y-coordinates; the pulse dispersing means is provided with a scanner having a mirror for reflecting the pulsed laser light oscillating at the repeated frequency M, and shaking the pulsed laser at a repeated frequency M1 lower than the repeated frequency M The scattered light rays are distributed to (M / M1) coordinates, the Y coordinate dispersion method to disperse the pulsed laser light rays to the plurality of Y coordinates, and the X coordinate dispersion method to disperse the plurality of X coordinates. The first main scanner is shaken with the repeated frequency M1, and the first auxiliary scanner is shaken at the repeated frequency of the multiple of the repeated frequency M1 to disperse the pulsed laser light, so that the first main scanner and the The phase of the iterative frequency of the first auxiliary scanner is staggered to identify the Y-coordinate illuminated by the pulsed laser light. The X-coordinate dispersion means includes a second main scanner that is shaken at the iterative frequency M1 and the iterative frequency M1. The second sub-scanner that shakes the pulse laser light at an integral multiple of the repeated frequency, disperses the phase of the repeated frequencies of the second main scanner and the second sub-scanner to identify that it is illuminated by the pulsed laser light X coordinate.