KR20150146411A - Laser machining apparatus - Google Patents

Abstract

Provided is a laser machining apparatus which makes a right angle between a side wall of a groove, and a bottom wall as a cross section of the groove not in a V-shape. The laser machining apparatus comprises: a workpiece retaining unit to retain a workpiece; a laser beam irradiation unit to irradiate a laser beam to the workpiece retained by the workpiece retaining unit; an X-axis direction transportation unit which moves the workpiece retaining unit and the laser beam irradiation unit to a processing transportation direction (X-axis direction) relatively; and a Y-axis direction transportation unit which moves the workpiece retaining unit and the laser beam irradiation unit to a Y-axis direction orthogonal to the X-axis direction by processing. The laser beam irradiation unit comprises: a laser beam oscillation unit to oscillate a laser beam; a condensing lens which condenses the laser beam oscillated from the laser beam oscillation unit, and irradiates the laser beam to the workpiece retained on a chuck table; and an optical axis inclining unit arranged between the laser beam oscillation unit and the condensing lens, making the optical axis of the laser beam be eccentric to a center axis of the condensing lens, and makes the optical axis of the laser beam be inclined to the center axis of the condensing lens.

Description

[0001] LASER MACHINING APPARATUS [0002]

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 a line to be divided which is arranged in a lattice pattern on the surface of a semiconductor wafer, which is substantially 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 devices.

As a method of dividing the above-mentioned semiconductor wafer along a line to be divided, a laser processing groove is formed by irradiating a wafer with pulsed laser light having a wavelength having an absorbing property along a line to be divided and performing ablation processing, And a method of breaking the same is proposed.

The laser processing apparatus for performing the laser processing includes a workpiece holding means for holding a workpiece, a laser beam irradiation means for applying a laser beam to the workpiece held by the workpiece holding means, A processing transfer means for relatively moving the light beam irradiation means in the processing transfer direction and an indexing transfer means for relatively moving the workpiece holding means and the laser beam irradiation means in the indexing transfer direction perpendicular to the processing transfer direction , See Patent Document 1).

Patent Document 1: JP-A-2006-253432

Thus, when the laser processing groove is formed by irradiating the workpiece with the laser beam, there is a problem that the groove has a V-shaped cross section and thus the processing does not proceed.

Further, since the groove width is not uniform from the incident side of the laser beam toward the bottom of the groove, there is a problem that when the groove is formed, the boundary between the side wall and the bottom wall of the groove is not perpendicular.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its main object is to provide a laser processing apparatus in which the cross section of a groove is not V-shaped and the angle between the side wall and the bottom wall of the groove is perpendicular.

According to an aspect of the present invention, there is provided a workpiece holding apparatus including a workpiece holding means for holding a workpiece, a laser beam irradiating means for applying a laser beam to the workpiece held by the workpiece holding means, Axis direction transfer means for relatively moving the laser beam irradiation means in the X-axis direction and the X-axis direction transfer means for relatively moving the laser beam irradiation means in the Y-axis direction orthogonal to the X- A laser processing apparatus comprising a Y-axis direction transfer means,

A condensing lens for condensing the laser beam emitted from the laser beam emitting means and irradiating the workpiece held on the chuck table, and a condensing lens for condensing the laser beam emitted from the laser beam emitting means And an optical axis tilting means disposed between the condensing lenses for eccentricity of the optical axis of the laser beam with respect to the central axis of the condensing lens and tilting the optical axis of the laser beam with respect to the central axis of the condensing lens on the condensing side Is provided.

The optical axis tilting means is constituted by a Y-axis direction tilting unit for moving the optical axis of the laser beam emitted from the laser beam generating means in the Y-axis direction with respect to the central axis of the condensing lens.

The optical axis tilting means is constituted by a Y-axis direction tilting unit and an X-axis direction scanning unit which moves the optical axis of the laser beam emitted from the laser beam generating means in the X-axis direction with respect to the central axis of the condensing lens.

In the laser machining apparatus according to the present invention, the laser beam irradiating means includes a laser beam emitting means for emitting a laser beam, a condensing means for condensing a laser beam emitted from the laser beam emitting means, And a condenser lens disposed between the laser beam oscillation means and the condenser lens so as to eccentricize the optical axis of the laser beam with respect to the central axis of the condenser lens and to tilt the optical axis of the laser beam with respect to the central axis of the condenser lens, In the case of forming the laser processing grooves in the X axis direction, the optical axis of the laser beam is alternately oscillated in the Y axis direction while being inclined while irradiating the laser processing groove to be formed, To form a laser machining groove having both side walls parallel to the bottom wall There.

In addition, since the laser processing groove formed in the workpiece (the groove width from the incident side of the laser beam toward the bottom of the groove is not uniform, the boundary between the side wall and the bottom wall of the groove is not perpendicular to the groove when the groove is formed) In the case of crystal processing, the boundary line between the sidewall and the bottom wall in the laser machining groove can be formed at a substantially right angle by irradiating the boundary line between the sidewall and the bottom wall forming the groove with the optical axis of the laser beam inclined.

1 is a perspective view of a laser machining apparatus constructed in accordance with 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.
3 is a block diagram showing another embodiment of the laser beam irradiation means shown in Fig.
Fig. 4 is a block diagram of an X-axis direction scanning unit equipped in the laser beam irradiation means shown in Fig. 2; Fig.
Fig. 5 is a block diagram of control means provided in the laser machining apparatus shown in Fig. 1. Fig.
6 is a perspective view showing a state in which a silicon substrate as a workpiece is adhered to a surface of a dicing tape mounted on an annular frame;
Fig. 7 is an explanatory diagram of a laser machining groove forming step performed on a silicon substrate as a workpiece by using the laser machining apparatus shown in Fig. 1; Fig.
8 is a cross-sectional view of a laser machining groove formed by conventional laser machining.
Fig. 9 is an explanatory diagram of a laser machining groove correcting step performed using the laser machining apparatus shown in Fig. 1;

Best Mode for Carrying Out the Invention 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 shows a perspective view of a laser machining apparatus constructed in accordance with the present invention. The laser machining apparatus shown in Fig. 1 is provided with a stationary base 2 and a chuck table 2 which is movably arranged in the processing transfer direction (X-axis direction) indicated by an arrow X in the stationary base 2, A mechanism 3 and a laser beam irradiation unit 4 as a laser beam irradiation means arranged on the base 2. [

The chuck table 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 pair of guide rails 31 and 31 arranged on the guide rails 31 and 31 in the X- (Y-axis direction) indicated by an arrow (Y) orthogonal to the X-axis direction on the first active block (32), and a second active block A second active block 33, a support table 35 supported by the cylindrical member 34 on the second active block 33 and a chuck table 36 as a workpiece holding means. The chuck table 36 is provided with a chucking chuck 361 made of a porous material. The chuck table 36 is provided with a suction chuck 361 on the holding surface which is the upper surface of the chucking chuck 361 by a suction means 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 provided with a pair of to-be-guided grooves 321 and 321 which are engaged with the pair of guide rails 31 and 31 on the bottom surface thereof and parallel to the Y- A pair of guide rails 322 and 322 are formed. The first active block 32 constructed as described above is moved in the X-axis direction along the pair of guide rails 31, 31 by engaging the guided grooves 321, 321 with the pair of guide rails 31, Lt; / RTI > The chuck table mechanism 3 in the illustrated embodiment includes X-axis direction moving means 37 for moving the first active block 32 along the pair of guide rails 31, 31 in the X-axis direction Respectively. The X axis direction transfer means 37 includes a male screw rod 371 disposed in parallel between the pair of guide rails 31 and 31 and a pulse motor 372 for rotationally driving the male screw rod 371 As shown in Fig. 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 of the male screw rod 371 is electrically connected to the output shaft of the pulse motor 372. The male thread rod 371 is screwed to a through-hole formed in a female screw block (not shown) protruding from the center bottom face of the first active block 32. Therefore, the first active block 32 is moved along the guide rails 31, 31 in the X-axis direction by driving the male screw rod 371 by forward rotation and reverse rotation by the pulse motor 372. [

The second active block 33 is provided with a pair of to-be-guided grooves 331 and 331 on its bottom surface for engaging with a pair of guide rails 322 and 322 provided on the upper surface of the first active block 32 And is configured to be movable in the Y-axis direction by engaging the guided grooves 331, 331 with the pair of guide rails 322, 322. The chuck table mechanism 3 in the illustrated embodiment is configured to move the second active block 33 along the pair of guide rails 322 and 322 provided in the first active block 32 in the Y axis direction And a Y-axis direction transporting means 38 are provided. The Y axis direction transfer means 38 includes a male screw rod 381 disposed parallel to the pair of guide rails 322 and 322 and a pulse motor 382 for rotationally driving the male screw rod 381 As shown in Fig. One end of the male screw rod 381 is rotatably supported by a bearing block 383 fixed to the upper surface of the first active block 32 and the other end of the male screw rod 381 is electrically connected to the output shaft of the pulse motor 382 . The male thread rod 381 is threadedly engaged with a through-hole formed in a female screw block (not shown) provided to protrude from a central lower surface of the second active block 33. Accordingly, the second active block 33 is moved in the Y-axis direction along the guide rails 322 and 322 by driving the male screw rod 381 by forward and reverse rotations by the pulse motor 382. [

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, A laser beam irradiating means 5 disposed at the front end of the casing 42 and an imaging means 6 disposed at the front end of the casing 42 for detecting a machining region to be laser machined. In the illustrated embodiment, the image pickup means 6 includes, in addition to a normal image pickup device (CCD) picked up by visible light, infrared light illumination means for irradiating the workpiece with infrared light, And an image pickup element (infrared CCD) for outputting an electric signal corresponding to the infrared ray captured by the optical system, and sends the picked-up image signal to the control means described later.

The laser beam irradiation means 5 will be described with reference to Fig.

The laser beam irradiating means 5 comprises a pulse laser beam oscillation means 51 for oscillating a pulsed laser beam and a pulse laser beam oscillation means 51 for condensing the pulsed laser beam emitted from the pulsed laser beam oscillation means 51, And a condenser lens 52 having a condenser lens 52 for irradiating the workpiece W to be processed and a condenser lens 52 disposed between the pulsed laser beam generator 51 and the condenser lens 52, And an optical axis tilting means 53 for eccentricity of the optical axis of the laser beam to tilt the optical axis of the laser beam with respect to the central axis of the condenser lens 52 on the condensing side. The pulse laser beam emitting means 51 is constituted by a YAG laser oscillator 511 and a repetition frequency setting means 512 attached thereto.

In the embodiment shown in Fig. 2, the optical axis tilting means 53 is configured such that the optical axis of the laser beam oscillated from the pulsed laser beam oscillation means 51 is moved in the Y-axis direction with respect to the central axis of the condensing lens, (54). The Y-axis direction tilting unit 54 includes a first galvanometer scanner 541, a second galvanometer scanner 542, and an optical axis changing mirror 543. The first galvanometer scanner 541 includes a first mirror 541a and an angle adjustment actuator 541b for adjusting the installation angle of the first mirror 541a and the angle adjustment actuator 541b is connected to a control means . The first galvanometer scanner 541 configured as described above reflects the pulsed laser beam emitted by the pulsed laser beam emitting means 51 toward the second galvanometer scanner 542. The second galvanometer scanner 542 includes a second mirror 542a and an angle adjustment actuator 542b for adjusting the installation angle of the second mirror 542a and the angle adjustment actuator 542b is connected to a control means . The second galvanometer scanner 542 configured as described above is configured so that the pulsed laser beam emitted by the pulsed laser beam oscillation means 51 and reflected by the first galvanometer scanner 541 is directed toward the optical axis changing mirror 543 Reflection. The optical axis changing mirror 543 rotates a pulsed laser beam emitted by the pulsed laser beam oscillation means 51 and guided through the first galvanometer scanner 541 and the second galvanometer scanner 542 to a condenser lens 52). The condenser 520 having the condenser lens 52 is disposed at the front end of the casing 42 as shown in Fig. Further, the condenser 520 is moved in the light-converging point position adjusting direction (Z-axis direction) by the light-convergence point position adjusting means (not shown).

The Y-axis direction tilting unit 54 in the illustrated embodiment is configured as described above, and its operation will be described below.

In the state where the first mirror 541a and the second mirror 542a of the first galvanometer scanner 541 and the second galvanometer scanner 542 are positioned at positions indicated by solid lines in Fig. 2, The pulsed laser beam oscillated by the laser beam oscillation means 51 is focused on the light-converging point P1 through the optical axis changing mirror 543 and the condenser lens 52 as shown by the solid line. The first mirror 541a and the second mirror 542a of the first galvanometer scanner 541 and the second galvanometer scanner 542 are the same in the one direction from the solid line position as indicated by the broken line in Fig. The pulsed laser beam oscillated by the pulsed laser beam oscillation means 51 is guided to the central axis of the condenser lens 52 through the optical axis changing mirror 543 and the condenser lens 52 as shown by the broken line, The light axis is inclined with respect to the light-converging point P1. The first mirror 541a and the second mirror 542a of the first galvanometer scanner 541 and the second galvanometer scanner 542 are moved from the solid line position as shown by the two-dot chain line in Fig. The pulsed laser beam oscillated by the pulsed laser beam oscillation means 51 is reflected by the condenser lens 52 through the optical axis changing mirror 543 and the condenser lens 52 as shown by the two- The light axis is inclined with respect to the central axis of the light-converging point P1.

On the other hand, the first mirror 541a and the second mirror 542a of the first galvanometer scanner 541 and the second galvanometer scanner 542 are moved from the state of FIG. 2 to the position of the second galvanometer scanner 542 When the rotation angle of the second mirror 542a is slightly shifted, the pulsed laser beam oscillated by the pulsed laser beam oscillation means 51 is reflected by the optical axis changing mirror 543 and the condenser lens 543 The light beam is converged at the light-converging point P2 by inclining the optical axis with respect to the central axis of the condenser lens 52 through the optical axis changing mirror 54 and the condenser lens 52, The light axis is inclined with respect to the central axis of the light source 52 and is condensed at the light-converging point P3. Thus, by appropriately adjusting the installation angles of the first mirror 541a and the second mirror 542a of the first galvanometer scanner 541 and the second galvanometer scanner 542, the pulsed laser beam oscillation means 51 ) Can be converged at an arbitrary position in the Y-axis direction at an arbitrary tilt angle.

Next, another embodiment of the optical axis tilting means 53 will be described with reference to Fig.

The optical axis tilting means 53 shown in Fig. 4 is disposed between the Y-axis direction tilting unit 54 and the condenser lens 52 and guides the optical axis of the laser beam oscillated from the pulsed laser beam oscillation means 51, And an X-axis direction scanning unit 55 for moving the X-axis direction with respect to the central axis. The X-axis direction scanning unit 55 includes a direction conversion mirror 551 for converting the pulsed laser beam reflected by the optical axis changing mirror 543 of the Y-axis direction tilting unit 54 in the horizontal direction, And a third galvanometer scanner 552 for moving the optical axis of the pulse laser beam redirected by the conversion mirror 551 in the X-axis direction with respect to the central axis of the condenser lens 52. The third galvanometer scanner 552 includes a third mirror 552a and an angle adjustment actuator 552b for adjusting the installation angle of the third mirror 552a and the angle adjustment actuator 552b is controlled by a control Lt; / RTI > In a state where the third mirror 552a of the third galvanometer scanner 552 is positioned at the position indicated by the solid line in Fig. 4, the X-axis direction scanning unit 55 configured in this manner is rotated in the X- 551 is focused on the light-converging point Pa through the condenser lens 52 as shown by the solid line. In the state where the third mirror 552a of the third galvanometer scanner 552 is positioned at the position indicated by the broken line in Fig. 4, the pulsed laser beam guided through the direction conversion mirror 551 is reflected by the broken line Is converged at the light-converging point Pb through the condenser lens 52 as shown in Fig. In the state where the third mirror 552a of the third galvanometer scanner 552 is positioned at the position indicated by the two-dot chain line in Fig. 4, the pulse laser beam 551 guided through the direction conversion mirror 551, Is condensed at the light-converging point Pc through the condenser lens 52 as indicated by the two-dot chain line. Thus, by controlling the operation of the angle-adjusting actuator 552b, the optical axis of the pulsed laser beam oscillated by the pulsed laser beam oscillation means 51 can be oscillated in the X-axis direction with respect to the central axis of the condenser lens 52 .

The laser processing apparatus in the illustrated embodiment is provided with the control means 8 shown in Fig. The control means 8 is constituted by a computer and includes a central processing unit (CPU) 81 for performing arithmetic processing according to a control program, a read only memory (ROM) 82 for storing a control program and the like, A random access memory (RAM) 83 for reading and writing data, and an input interface 84 and an output interface 85. The input / A detection signal from the image pickup means 6 or the like is input to the input interface 84 of the control means 8. The X axis direction transfer means 37, the Y axis direction transfer means 38, the pulse laser beam emitting means 51, the first galvanometer scanner The angle adjustment actuator 542b of the second galvanometer scanner 542 and the angle adjustment actuator 552b of the third galvanometer scanner 552 and the like.

The laser processing apparatus in the illustrated embodiment is configured as described above, and its operation will be described below.

6 shows a perspective view of a silicon substrate as a workpiece. The silicon substrate 10 shown in Fig. 6 is formed in a circular shape with a thickness of, for example, 200 mu m, and a machining line 101 is set on the surface. This silicon substrate 10 is adhered to the surface of the protective tape T mounted on one side of the annular frame F. [

A description will be given of a first embodiment in which the above-described silicon substrate 10 as the workpiece is subjected to laser machining using the laser machining apparatus.

First, the protective tape T side of the silicon substrate 10 is disposed on the chuck table 36 of the laser processing apparatus shown in Fig. Then, a suction means (not shown) is operated to suck and hold the silicon substrate 10 on the chuck table 36 through the protective tape T (workpiece holding step).

The chuck table 36 with the silicon substrate 10 sucked and held as described above is positioned directly below the imaging means 6 by the X axis direction transfer means 37. [ When the chuck table 36 is positioned just below the image pickup means 6 in this way, the machining area to be laser-machined on the silicon substrate 10 is detected by the image pickup means 6 and the control means 8 Execute the alignment operation. The imaging means 6 and the control means 8 are provided with a processing line 101 formed on the silicon substrate 10 and a laser beam irradiation means 5 for irradiating a laser beam along the processing line 101, Such as pattern matching, for alignment of the condenser 520 constituting the laser beam irradiation position, and performs alignment of the laser beam irradiation position.

When the processing line 101 formed on the silicon substrate 10 held on the chuck table 36 is detected and alignment of the laser beam irradiation position is performed as described above, The chuck table 36 is moved to the laser beam irradiation area where the condenser 520 of the laser beam irradiating means 5 for irradiating the laser beam is located and one end of the predetermined processing line 101 (left end in a) is positioned directly below the condenser 520 of the laser beam irradiating means 5. The control means 8 controls the light-converging point position adjusting means (not shown) to position the light-converging point of the pulsed laser beam irradiated from the condenser 520 near the upper surface of the silicon substrate 10. Next, the control means 8 controls the pulsed laser beam oscillation means 51 to irradiate the silicon substrate 10 from the condenser 520 with a pulsed laser beam having a wavelength of absorbing wavelength, The angle adjusting actuator 541b and the angle adjusting actuator 542b of the first galvanometer scanner 541 and the second galvanometer scanner 542 are controlled to change the first mirror 541a and the second mirror 542a The chuck table 36 is controlled in the direction indicated by the arrow X1 in FIG. 7A by controlling the X-axis direction conveying means 37 while alternately changing the state of the broken line and the state of the two- (Laser machining groove forming step). Therefore, as shown in Fig. 7 (c), the optical axis of the laser beam irradiated on the silicon substrate 10 oscillates in the Y-axis direction alternately with the broken line state and the two-dot chain line state. As a result, as shown in Fig. 7C, side walls 110b and 110c are formed on the silicon substrate 10 from the incident side (upper surface) of the laser beam toward the bottom wall 110a along the processing line 101 Parallel laser processing grooves 100 are formed. 7 (b), when the other end of the machining line 101 (the right end in Fig. 7 (b)) reaches the irradiating position of the condenser 520, the irradiation of the pulsed laser beam is stopped The movement of the chuck table 36 is stopped. As a result, as shown in Fig. 7 (b), the side walls 110b and 110c are parallel to each other along the processing line 101 as shown in Fig. 7 (c) And the laser processing grooves 100 are formed at right angles to the bottom 110a.

In the above-described laser machining groove forming step, the operation of the angle adjusting actuator 552b constituting the third galvanometer scanner 552 of the X-axis direction scanning unit 55 shown in Fig. 4 is controlled so that the third mirror 552a In the X axis direction with respect to the central axis of the condenser lens 52, the laser beam can be irradiated while the optical axis of the laser beam is oscillated in the X axis direction, The formation of the laser machining groove 100 can be promoted.

The processing conditions in the laser machining groove forming step are set as follows, for example.

Wavelength of laser beam: 355 nm

Repetition frequency: 50 ㎑

Average power: 3 W

Condensing spot diameter:? 10 m

Processing feed rate: 100 mm / sec

Next, a description will be given of a second embodiment in which laser processing is performed on the silicon substrate 10 as the above-described workpiece using the laser processing apparatus.

This second embodiment relates to a modification processing of the laser processing groove 120 formed along the processing line 101 on the silicon substrate 10 as shown in Fig. The side walls 120b and 120c are not parallel but tapered as shown in FIG. 8, and the boundary line between the side walls 120b and 120c and the bottom wall 120a are not perpendicular to each other Do not. In the second embodiment, the side walls 120b and 120c of the laser machining groove 120 are processed as shown by broken lines so as to correct the boundary line between the side walls 120b and 120c and the bottom wall 120a to be perpendicular to each other.

In order to perform processing for correcting the boundary line between the side walls 120b and 120c of the laser processing groove 120 formed in the silicon substrate 10 and the bottom wall 120a at right angles, The vicinity of the boundary line between the side wall 120b and the bottom wall 120a in the laser processing groove 120 is positioned below the condenser lens 52 as shown in FIG. Then, the control means 8 controls the light-converging point position adjusting means (not shown) so that the irradiating position of the pulsed laser beam irradiated from the condenser 520 is set in the laser machining groove 120 as shown in Fig. 9 (a) In the vicinity of the boundary line between the side wall 120b and the bottom wall 120a. Next, the control means 8 controls the pulsed laser beam oscillation means 51 to irradiate the silicon substrate 10 from the condenser 520 with a pulsed laser beam having a wavelength of absorbing wavelength, The angle adjusting actuator 541b and the angle adjusting actuator 542b of the first galvanometer scanner 541 and the second galvanometer scanner 542 are controlled to change the first mirror 541a and the second mirror 542a The chuck table 36 is moved in the X-axis direction (in Fig. 9 (a)) by changing the X-axis direction transfer means 37 while alternately changing the state of the broken line and the state of the two- (The first laser machining groove correcting step). As a result, the boundary line between the side wall 120b and the bottom wall 120a in the laser machining groove 120 is formed at a substantially right angle as shown in Fig. 9 (b).

Next, a process of correcting the boundary line between the side wall 120c and the bottom wall 120a of the laser machining groove 120 to be orthogonal is performed. The control means 8 controls the Y-axis direction transfer means 38 from the state in which the first laser machining groove correcting process is performed so that the side wall of the laser machining groove 120 in the laser machining groove 120 120c and the bottom wall 120a is positioned below the condenser lens 52. [ Then, the control means 8 controls the light-converging point position adjusting means (not shown) so that the irradiating position of the pulsed laser beam irradiated from the condenser 520 is set in the laser machining groove 120 as shown in Fig. 9 (b) In the vicinity of the boundary line between the side wall 120c and the bottom wall 120a. Next, the control means 8 controls the pulsed laser beam oscillation means 51 to irradiate the silicon substrate 10 from the condenser 520 with a pulsed laser beam having a wavelength of absorbing wavelength, The angle adjusting actuator 541b and the angle adjusting actuator 542b of the second galvanometer scanner 541 and the second galvanometer scanner 542 are controlled so that the first mirror 541a and the second mirror 542a are rotated The chuck table 36 is moved in the X-axis direction (in Fig. 9 (b), in a direction perpendicular to the plane of the paper in Fig. 9 (b)) by alternately changing the dashed- (The second laser machining groove correcting step). As a result, the boundary line between the side wall 120c and the bottom wall 120a in the laser machining groove 120 is formed at a substantially right angle as shown in Fig. 9 (c).

As described above, by performing the first laser machining groove correcting step and the second laser machining groove correcting step, the laser machining groove 120 formed on the silicon substrate 10 as shown in Fig. 9 (c) The boundaries between the side walls 120b and 120c and the bottom wall 120a are modified to be substantially perpendicular.

Further, even when the first laser machining groove correcting step and the second laser machining groove correcting step are performed, the angle adjustment of the third galvanometer scanner 552 of the X-axis direction scan unit 55 shown in FIG. The operation of the actuator 552b is controlled so that the third mirror 552a is alternately positioned at the position indicated by the broken line and the position indicated by the two-dot chain line as shown in Fig. 4, so that the optical axis of the laser beam is converged on the condenser lens 52, The laser beam can be irradiated while being swung in the X-axis direction with respect to the central axis of the laser machining groove 100, so that formation of the laser machining groove 100 can be promoted.

Although the present invention has been described based on the embodiments shown above, the present invention is not limited to the embodiments, and various modifications are possible within the scope of the present invention. For example, in the above-described embodiment, the Y-axis direction tilting unit 54 and the X-axis direction scanning unit 55 as the optical axis tilting means 53 have been described using the galvanometer scanner. However, (AOE), an electro-optical element (EOD), a polygon mirror, or the like may be used.

2: stop base 3: chuck table mechanism
36: chuck table 37: X-axis direction conveying means
38: Y-axis direction transfer means 4: laser beam irradiation unit
5: laser beam irradiation means 51: pulse laser beam emission means
52: condenser lens 53: optical axis tilting means
54: Y-axis direction tilting unit 541: First galvanometer scanner
542: Second galvanometer scanner 543: Optical axis change mirror
55: X-axis direction scanning unit 551: direction conversion mirror
552: third galvanometer scanner 6: imaging means
8: control means 10: silicon substrate

Claims (3)

A laser processing apparatus comprising:
A workpiece holding means for holding a workpiece; a laser beam irradiating means for irradiating a workpiece held by the workpiece holding means with a laser beam; and a workpiece holding means for holding the workpiece holding means and the laser beam irradiating means in a processing- Axis direction; and a Y-axis direction transfer means for transferring the workpiece holding means and the laser beam irradiation means in the Y-axis direction orthogonal to the X-axis direction, In the processing apparatus,
The laser beam irradiation means
A laser beam oscillation means for oscillating a laser beam,
A condensing lens for condensing the laser beam emitted from the laser beam generating means and irradiating the workpiece held on the chuck table,
An optical axis tilting means disposed between the laser beam emitting means and the condensing lens for eccentricity of the optical axis of the laser beam with respect to the central axis of the condensing lens and inclining the optical axis of the laser beam with respect to the central axis of the condensing lens on the condensing side,
And a laser processing unit for processing the laser beam. The laser processing apparatus according to claim 1, wherein the optical axis tilting means is constituted by a Y-axis direction tilting unit for moving the optical axis of the laser beam oscillated from the laser beam oscillation means in the Y-axis direction with respect to the central axis of the condensing lens Device. The optical scanning apparatus according to claim 2, wherein the optical axis tilting means comprises: a Y-axis direction tilting unit; and an X-axis direction scanning unit for moving the optical axis of the laser beam emitted from the laser beam generating unit in the X- Wherein the laser processing unit comprises a laser processing unit.

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