TW201607659A - Laser processing device - Google Patents

Abstract

The subject of the present invention is to provide a laser processing device capable of forming a laser-processed groove with a uniform depth without controlling the output of a laser beam. To solve the problem, the laser processing device comprises a processed object holding means for holding a processed object, and a laser beam irradiation means for irradiating a laser beam on the processed object held by the processed object holding means. The laser beam irradiation means is composed of a pulse laser beam oscillation means, a condenser for condensing the pulse laser beam, and a scanning mirror arranged between the pulse laser beam oscillation means and the condenser for scanning and guiding the pulse laser beam generated by the oscillation of the pulse laser beam oscillation means to the condenser. The laser processing device further comprises a processing depth detection means for detecting the processing depth of the processed objected held by the processed object holding means. The processing depth detection means includes: an inspection light source for emitting inspection light with a predetermined wavelength band toward the scanning mirror; a color difference lens arranged between the inspection light source and the scanning mirror for splitting light corresponding to the wavelength of the inspection light and slightly modifying the expansion angle of the inspection light according to the wavelength; a beam splitter arranged between the inspection light source and the color difference lens for diverting the reflection light of the inspection light irradiated onto the processed object to the reflection light detection path; a wavelength screening means arranged on the reflection light detection path for allowing the reflection light of the processed object with a wavelength consistent to the focal point to pass through the wavelength screening means; a wavelength detection means for detecting the wavelength of the reflection light passing through the wavelength screening means; and a control means for determining the processing depth of the processed object according to the wavelength detected by the wavelength detection means.

Description

Laser processing device Field of invention

The present invention relates to a laser processing apparatus that performs laser processing on a workpiece such as a semiconductor wafer held on a work chuck.

Background of the invention

In the manufacturing process of the semiconductor device, a plurality of regions are divided by a predetermined dividing line arranged in a lattice shape on the surface of the substantially disk-shaped semiconductor wafer, and ICs, LSIs, and the like are formed in the divided regions. Device. Further, by dicing the semiconductor wafer along a street to divide the region in which the device is formed, individual semiconductor devices are fabricated.

Recently, in order to improve the processing capability of semiconductor wafers such as ICs and LSIs, semiconductor wafers in the form of semiconductor devices formed by functional layers on the surface of germanium substrates are being put into practical use. The functional layers will be composed of SiOF, BSG (SiOB). a film of an inorganic substance, or a film of a low dielectric constant insulator (Low-k film) composed of a film of an organic substance such as a polymer film such as a polyimine or a parylene. Laminated.

The segmentation along the dicing streets of such semiconductor wafers is typically performed in a cutting device called a dicer. The cutting device is provided with a working chuck for holding a semiconductor wafer as a workpiece, and is used for cutting A cutting means for cutting a semiconductor wafer held on the working chuck, and a moving means for moving the working chuck and the cutting means. The cutting means includes a rotary spindle that rotates at a high speed and a cutter that is mounted on the spindle. The cutting blade is composed of a disk-shaped base and an annular cutting edge attached to the outer peripheral portion of the side surface of the base. The cutting edge is formed by fixing, for example, diamond abrasive grains having a particle diameter of about 3 μm by electroforming. .

However, it is difficult to cut the above Low-k film with a cutter. That is, since the Low-k film is very brittle like mica, when the cutting is performed along the dividing line by the cutting blade, the Low-k film peels off, and the peeling or even reaching the circuit causes fatality to the device. The problem of damage.

Further, in a semiconductor wafer in which a test metal film called a test element group (TEG) for testing a device function in a functional layer on a division predetermined line is disposed, there is the following problem: When the cutter is cut, burrs are generated to deteriorate the quality of the device, and the dressing of the cutter must be frequently performed to reduce the productivity.

In order to solve the above problem, a method of dividing a wafer by irradiating laser light along a predetermined dividing line formed on a semiconductor wafer by the Low-k film is disclosed in Patent Document 1 listed below. Forming a laser processing groove on the formed laminated body to break the functional layer, and relatively moving the cutting blade and the semiconductor wafer by positioning the cutting tool on the laser processing groove that has broken the functional layer The semiconductor wafer is cut along a predetermined dividing line.

However, a test metal called a test element group (TEG) is provided with a device function for testing a function layer in a division line. In a semiconductor wafer of a film, there is a problem that a laser processing groove having a uniform depth cannot be formed along a predetermined dividing line. In order to solve this problem, Patent Document 2 listed below discloses a technique of detecting a region in which a metal film for testing is disposed to fabricate and store coordinates, and adjusting the output of the laser light while dividing along the stored coordinates. The predetermined line illuminates the laser light.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-64231

Patent Document 2: Japanese Patent Laid-Open Publication No. 2005-118832

Summary of invention

However, it is necessary to detect the area in which the metal film for test is disposed to form a coordinate like the technique disclosed in the above-mentioned Patent Document 2, which may require a lot of time to deteriorate the productivity, and the coordinates of the coordinate are controlled in accordance with the coordinates. The output of the light is not necessarily easy.

The present invention has been made in view of the above circumstances, and a main technical object thereof is to provide a laser processing apparatus capable of forming a laser processing groove of uniform depth without controlling the output of laser light.

In order to solve the above-mentioned main technical problems, the laser processing apparatus according to the present invention is provided with means for holding a workpiece to hold a workpiece, and processing to be held by the workpiece holding means by irradiating laser light. Laser processing device for laser light irradiation on an object The laser light irradiation means is composed of: a pulsed laser ray oscillating means for oscillating to generate pulsed laser light; and a concentrator for concentrating the pulsed laser light oscillated from the pulsed laser oscillating means Light is incident on the workpiece held by the workpiece holding means; and a scanning mirror is disposed between the pulsed laser ray oscillating means and the concentrator, and the laser light oscillating means The pulsed laser light generated by the oscillation is scanned and guided to the concentrator, and is provided with a processing depth detecting means for detecting the processing depth of the workpiece held by the workpiece holding means, and the processing depth detecting means is The following is configured to: inspect the light source, and emit inspection light having a predetermined wavelength band toward the scanning mirror; the color difference lens is disposed between the inspection light source and the scanning mirror, and is divided according to the wavelength of the inspection light, and is divided into The wavelengths of the inspection light are slightly changed; a beam splitter is disposed between the inspection light source and the color difference lens, and is emitted from the inspection light source. The scanning mirror and the illuminator illuminate the reflected light of the inspection light irradiated on the workpiece held by the workpiece holding means to the reflected light detecting path; and the wavelength screening means is disposed in the reflected light detecting path And passing the reflected light of the inspection light of a wavelength at which the processed object and the focus coincide with each other in the wavelength band of the reflected light; The wavelength detecting means detects the wavelength of the reflected light of the inspection light that has passed through the wavelength screening means, and the control means determines the workpiece to be processed by the workpiece holding means based on the wavelength detected by the wavelength detecting means Processing depth.

The laser processing apparatus of the present invention is configured as described above, and is capable of detecting the laser beam irradiation means while irradiating the laser beam to the workpiece held by the workpiece holding means while detecting the processing depth by means of the processing depth detecting means. The depth of the processed laser processing groove, and once the laser processing groove reaches a predetermined thickness, the irradiation of the laser light toward the workpiece is stopped, so even if different materials are present on the workpiece, A uniform depth laser processing trench is formed without controlling the output of the laser light. Therefore, since it is not necessary to detect the regions in which different kinds of materials exist to make coordinates, productivity can be improved.

10‧‧‧Semiconductor wafer

110‧‧‧Substrate

110a‧‧‧ surface

110b‧‧‧ lower surface

120‧‧‧ functional layer

120a‧‧‧Surface

121‧‧‧Division line

122‧‧‧Device

123‧‧‧Metal film

130‧‧‧Laser processing ditch

2‧‧‧Standing abutment

3‧‧‧Working table mechanism

31, 322‧‧‧ rails

32‧‧‧1st slider

321,331‧‧‧guided ditch

33‧‧‧2nd slider

34‧‧‧Cylinder components

35‧‧‧Support table

36‧‧‧Working table

361‧‧‧Adsorption chuck

362‧‧‧ fixture

37‧‧‧Processing means of feeding

371, 381‧‧‧ male screw

372, 382‧‧ ‧ pulse motor

373, 383‧ ‧ bearing blocks

38‧‧‧Dividing means of feeding

4‧‧‧Laser light irradiation unit

41‧‧‧Support members

42‧‧‧shells

5‧‧‧Laser light exposure

51‧‧‧Pulse laser oscillating means

511‧‧‧pulse laser ray oscillator

512‧‧‧Repetition frequency setting means

52‧‧‧ concentrator

521‧‧‧fθ lens

53‧‧‧Scan mirror

530‧‧‧Scan motor

53a‧‧‧arrow

54‧‧‧ Optical axis change means

55‧‧‧Laser light absorption means

6‧‧‧Photography

7‧‧‧Processing depth detection means

71‧‧‧Check the light source

72‧‧‧chromatic aberration lens

73‧‧‧ Reflected light detection path

74‧‧‧beam splitter

75‧‧‧ Wavelength screening

751‧‧‧ Concentrating lens

752‧‧‧ pinhole mask

752a‧‧‧ pinhole

753‧‧‧ Collimating lens

76‧‧‧ Wavelength detection means

761‧‧‧diffraction grating

762‧‧‧ concentrating lens

763‧‧‧Line image sensor

8‧‧‧Control means

81‧‧‧Central Processing Unit (CPU)

82‧‧‧Read-only memory (ROM)

83‧‧‧ Random Access Memory (RAM)

84‧‧‧Input interface

85‧‧‧Output interface

F‧‧‧Ringed frame

LB, LB1, LBn‧‧‧ pulsed laser light

T‧‧‧ cutting tape

W‧‧‧Processed objects

X, X1, Y, Z‧‧‧ directions

P1, P2‧‧‧ spotlights

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a laser processing apparatus constructed in accordance with the present invention.

Fig. 2 is a block diagram showing the arrangement of a laser beam irradiation means and a processing depth detecting means provided in the laser processing apparatus shown in Fig. 1.

Fig. 3 is an explanatory view showing a light collecting point of each wavelength of the inspection light of the processing depth detecting means shown in Fig. 2;

Figure 4 is a block diagram showing the control means provided on the laser processing apparatus shown in Figure 1.

Figure 5 is a graph showing the relationship between the wavelength (nm) of the inspection light and the processing depth (μm). Control chart.

6(a) and 6(b) are a perspective view and a cross-sectional view of a main portion of a semiconductor wafer as a workpiece.

Fig. 7 is a perspective view showing a state in which the semiconductor wafer shown in Fig. 6 is attached to the surface of the dicing tape which has been mounted on the annular frame.

8(a) to 8(c) are explanatory views showing a laser processing groove forming step and a feeding step performed by the laser processing apparatus shown in Fig. 1.

Form for implementing the invention

Hereinafter, preferred embodiments of the laser processing apparatus constructed in accordance with the present invention will be described in more detail with reference to the accompanying drawings.

A perspective view of a laser processing apparatus constructed in accordance with the present invention is shown in FIG. The processing apparatus shown in Fig. 1 is provided with a stationary base 2, a working clamp that is arranged to be movable on the stationary base 2 in a machining feed direction (X-axis direction) indicated by an arrow X and to hold a workpiece. The stage mechanism 3 and the laser beam irradiation unit 4 which is disposed on the base 2 as a laser beam irradiation means.

The above-described work clamping mechanism 3 includes a pair of guide rails 31 and 31 which are arranged in parallel along the X-axis direction on the stationary base 2, and a first slide which is arranged to be movable in the X-axis direction on the guide rails 31 and 31. The block 32 is disposed so as to be movable on the first slider 32 in the index feeding direction (Y-axis direction) indicated by the arrow Y perpendicular to the machining feed direction (X-axis direction). 33. A support base 35 supported by the second slider 33 by the cylindrical member 34, and a work chuck 36 as a workpiece holding means. The working clamping table 36 is provided with an adsorption chuck 361 formed of a porous material, and is formed to be sucked by a drawing. The guiding means holds the semiconductor wafer, which is a workpiece, for example, in a circular holding surface on the upper surface of the chucking chuck 361. The work chuck 36 configured as described above is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. Further, a clamp 362 for fixing an annular frame is disposed on the work chuck 36, and the annular frame supports a workpiece such as a semiconductor wafer through a protective tape.

The first slider 32 is provided with a pair of guided grooves 321 and 321 fitted to the pair of guide rails 31 and 31 on the lower surface thereof, and is formed on the upper surface thereof in parallel along the Y-axis direction. A pair of guide rails 322, 322. The first slide block 32 configured as described above is configured to be fitted to the pair of guide rails 31 and 31 by the guide grooves 321 and 321 so as to be along the X-axis direction along the pair of guide rails 31 and 31. mobile. The work clamping mechanism 3 in the illustrated embodiment includes a machining feed means 37 for moving the first slider 32 in the X-axis direction along the pair of rails 31, 31. The machining feed means 37 includes a male screw 371 disposed in parallel between the pair of guide rails 31 and 31, and a drive source such as a pulse motor 372 for rotationally driving the male screw 371. The male screw 371 is rotatably supported at one end by a bearing block 373 fixed to the stationary base 2, and the other end thereof is driven and coupled by an output shaft of the pulse motor 372. Further, the male screw 371 is screwed into a through screw hole formed by a female nut (not shown) which is provided so as to protrude from the lower surface of the central portion of the first slider 32. Therefore, the first slider block 32 can be moved in the X-axis direction along the guide rails 31 and 31 by the forward rotation of the pulse motor 372 and the reverse rotation of the male screw 371.

The second slider 33 is configured to be fitted to a pair of guide rails 322 and 322 provided on the upper surface of the first slider 32 on the lower surface thereof. The pair of guided grooves 331 and 331 are movable in the Y-axis direction by fitting the guided grooves 331 and 331 to the pair of guide rails 322 and 322. The work clamping mechanism 3 in the illustrated embodiment includes an index feeding means for moving the second slider 33 along the pair of guide rails 322 and 322 attached to the first slider 32 in the Y-axis direction. 38. The index feeding means 38 includes a male screw 381 which is disposed in parallel between the pair of guide rails 322 and 322, and a drive source for a pulse motor 382 or the like for rotationally driving the male screw 381. The male screw 381 has one end supported by a bearing block 383 fixed to the upper surface of the first slider 32 so as to be rotatable, and the other end of which is rotatably coupled to the output shaft of the pulse motor 382. Further, the male screw 381 is screwed into a through screw hole formed by a female nut (not shown) which is provided so as to protrude from the lower surface of the central portion of the second slider 33. Therefore, by driving the male screw 381 by the forward rotation and the reverse rotation of the pulse motor 382, the second slider 33 can be moved in the Y-axis direction along the guide rails 322 and 322.

The laser beam irradiation unit 4 includes a support member 41 disposed on the base 2, a casing 42 supported by the support member 41 and extending substantially horizontally, and a laser beam irradiation means disposed in the casing 42. 5. An image pickup means 6 disposed at a front end portion of the casing 42 and capable of detecting a processing area for laser processing. Further, the imaging means 6 is provided with an illumination means for illuminating the workpiece, an optical system for capturing a region illuminated by the illumination means, and an imaging element (CCD) for capturing an image captured by the optical system, and the like. The captured image signal is transmitted to a control means described later.

The above-described laser beam irradiation means 5 will be described with reference to Fig. 2 .

The laser beam irradiation means 5 is composed of a pulsed laser beam oscillating means 51 for collecting the pulsed laser beam oscillated from the pulsed laser beam oscillating means 51 and illuminating the lens holder 36. The concentrator 52 on the workpiece W and the laser light arranged between the pulsed laser ray oscillating means 51 and the concentrator 52 and oscillated from the pulsed laser ray oscillating means 51 are scanned and guided. To the scanning mirror 53 of the concentrator 52. The pulsed laser ray oscillating means 51 is constituted by a pulsed laser ray oscillator 511 and a repetition frequency setting means 512 attached thereto. Further, in the illustrated embodiment, the pulsed laser beam 511 of the pulsed laser beam oscillating means 51 oscillates to generate a pulsed laser beam LB having a wavelength of 355 nm. The concentrator 52 is provided with an f θ lens 521 that condenses the pulsed laser beam LB oscillated by the pulsed laser ray oscillation means 51. Furthermore, the concentrator 52 is formed so as to be adjustable in the direction of the condensing point position perpendicular to the holding surface of the working gantry 36 by the condensing point position adjusting means (not shown) (in FIG. 1 Moves in the Z-axis direction indicated by the arrow Z).

In the illustrated embodiment, the scanning mirror 53 is constituted by a polygon mirror, and is rotated by a scanning motor 530 in a direction indicated by an arrow 53a in FIG. The pulsed laser beam LB generated by the oscillation is guided to the f θ lens 521 along the X-axis direction within the range of LB1 to LBn. Further, a current mirror (galvano-mirror) may be used as the scanning mirror 53. Further, the range of the pulsed laser beams LB1 to LBn condensed by the f θ lens 521 is drawn in an exaggerated manner in the illustrated embodiment, but may be set to, for example, 2 mm.

The laser beam irradiation means 5 in the illustrated embodiment includes a pulsed laser beam LB which is disposed between the pulsed laser beam oscillating means 51 and the scanning mirror 53, and is oscillated from the pulsed laser ray oscillating means 51. Light The optical axis changing means 54 for the axis deviation. In the illustrated embodiment, the optical axis changing means 54 is constituted by an acousto-optic element (AOD), and when RF (radio frequency) of a predetermined frequency is applied, it is indicated by a broken line in FIG. The optical axis of the pulsed laser beam LB is changed toward the laser beam absorbing means 55.

The pulsed laser beam oscillating means 51 of the laser beam irradiation means 5 configured as described above and the scan motor 530 and the optical axis changing means 54 of the scanning mirror 53 are controlled by a control means to be described later.

Referring to Fig. 2, the laser processing apparatus according to the illustrated embodiment includes a machining depth detecting means 7 for detecting the machining depth of the workpiece W held by the work chuck 36 as the workpiece holding means. The machining depth detecting means 7 includes an inspection light source 71, a chromatic aberration lens 72, a beam splitter 74, a wavelength screening means 75, and a wavelength detecting means 76. The inspection light source 71 emits inspection light having a predetermined wavelength band toward the scanning mirror 53 of the above-described laser beam irradiation means 5. The color difference lens 72 is disposed between the inspection light source 71 and the scanning mirror 53, and is split according to the wavelength of the inspection light, and slightly changes the expansion angle of the inspection light for each wavelength. The beam splitter 74 is disposed between the inspection light source 71 and the chromatic aberration lens 72, and the f θ lens 521 emitted from the inspection light source 71 and transmitted through the scanning mirror 53 and the concentrator 52 is irradiated to the keeper held by the operation gantry 36. The reflected light of the inspection light on the workpiece W is branched onto the reflected light detecting path 73. The wavelength selection means 75 is disposed on the reflected light detection path 73 so that the reflected light of the inspection light of the wavelength at which the focus can be aligned with the workpiece in the wavelength band of the reflected light passes. The wavelength detecting means 76 is a wavelength for detecting the reflected light of the inspection light having passed through the wavelength screening means 75.

The inspection light source 71 is composed of a superluminescent diode (SLD) or a flash bulb, and has a wavelength band of 800 to 900 nm in the illustrated embodiment. The chromatic aberration lens 72 splits the inspection light having a wavelength band of 800 to 900 nm emitted from the inspection light source 71 by a wavelength, and directs the expansion angle of the inspection light to the scanning mirror 53 with a slight change for each wavelength. Therefore, the inspection light having a wavelength band of 800 to 900 nm reflected on the scanning mirror 53 and guided to the f θ lens 521 forms a light of 800 nm concentrated on P1 as shown in FIG. 3, and the wavelength is 900 nm light is concentrated on P2. Further, in the illustrated embodiment, the interval between the condensed spot P1 having a wavelength of 800 nm and the condensed spot P2 having a wavelength of 900 nm is set to 50 μm. Therefore, in the illustrated embodiment, a control map showing the relationship between the wavelength (nm) of the inspection light and the processing depth (μm) shown in FIG. 5 is created, and the control map is stored in a memory of a control means to be described later. in.

The beam splitter 74 is configured such that the inspection light having the wavelength band of 800 to 900 nm emitted from the inspection light source 71 is directed toward and passing through the chromatic aberration lens 72, but the reflected light of the inspection light that has been irradiated on the working chuck 36 is directed toward the reflection. The light detection path 73 is divergent. The wavelength screening means 75 disposed on the reflected light detecting path 73 is a condensing lens 751, a pinhole mask which is disposed at a focus position of the condensing lens 751 on the downstream side of the condensing lens 751 and includes a pinhole 752a. 752, and a collimation lens 753 disposed on the downstream side of the pinhole mask 752 and forming reflected light that has passed through the pinhole 752a as parallel light. The wavelength selection means 75 configured as described above is a needle formed so that the reflected light of the wavelength reflected by the inspection light reflected on the workpiece W held by the work chuck 36 passes through the pinhole mask 752. Hole 752a. The wavelength detecting means 76 is composed of a diffraction grating 761, A condenser lens 762 and a line image sensor 763 are formed. The diffraction grating 761 diffracts the reflected light formed by the collimating lens 753 into parallel light, and transmits the diffracted signal corresponding to each wavelength to the line image sensor 763 through the collecting lens 762. The line image sensor 763 detects the light intensity in each wavelength of the reflected light diffracted by the diffraction grating 761, and transmits the detection signal to a control means to be described later.

The laser processing apparatus according to the embodiment shown in the drawings includes the control means 8 shown in FIG. The control means 8 is constituted by a computer, and includes a central processing unit (CPU) 81 that performs arithmetic processing in accordance with a control program, a read-only memory (ROM) 82 that stores a control program, and the like, and a readable and writable storage result. A random access memory (RAM) 83, an input interface 84, and an output interface 85 are provided. The input interface 84 of the control means 8 is input with detection signals from the imaging means 6, the line type image sensor 763, and the like. Then, the control signal is output from the output interface 85 of the control means 8 to the processing feed means 37, the index feed means 38, the pulsed laser ray oscillating means 51, the scan motor 530 of the scan mirror 53, and the optical axis. The changing means 54 and the inspection light source 71 of the processing depth detecting means 7 are used. Further, in the random access memory (RAM) 83, a control map showing the relationship between the wavelength (nm) of the inspection light and the processing depth (μm) shown in FIG. 5 is stored.

The processing apparatus in the embodiment shown in the drawings is configured as described above, and its action will be described below.

Fig. 6 (a) and (b) are a perspective view showing a semiconductor wafer as a workpiece and an enlarged cross-sectional view of a main portion.

The semiconductor wafer 10 shown in (a) and (b) of FIG. 6 is formed with a functional layer in which an insulating film and a functional film forming a circuit are laminated on a surface 110a of a substrate 110 having a thickness of 150 μm. In the functional layer 120, a device 122 such as an IC or an LSI is formed in a plurality of regions divided by a plurality of predetermined dividing lines 121 formed in a lattice shape. Further, in the embodiment shown in the figure, the insulating film forming the functional layer 120 is made of a SiO ₂ film or a film of an inorganic substance such as SiOF or BSG (SiOB) or a polyblyimide or parylene. A low dielectric constant insulator coating film (Low-k film) formed of a film of an organic substance such as a polymer film is formed, and the thickness is set to 10 μm. Further, a test metal film 123 called a test element group (TEG), which is a plurality of test element groups (TEG) for partially functioning the test device 122, is partially disposed on the division planned line 121 of the semiconductor wafer 10, and the test metal film 123 is It is formed of copper (Cu) and aluminum (Al).

When the semiconductor wafer 10 is processed along the planned dividing line, a wafer supporting step of attaching the semiconductor wafer 10 to the dicing tape attached to the annular frame is performed. That is, as shown in FIG. 7, the back surface 110b of the substrate 110 constituting the semiconductor wafer 10 is attached to a cut formed of a synthetic resin sheet such as polyolefin which has been mounted on the annular frame F. On the surface of the tape T. Therefore, the semiconductor wafer 10 attached to the surface of the dicing tape T has the surface 120a of the functional layer 120 as the upper side.

After the wafer supporting step described above is performed, the dicing tape T side of the semiconductor wafer 10 can be placed on the working chuck 36 of the laser processing apparatus shown in FIG. Then, the semiconductor wafer 10 is sucked and held on the work chuck 36 via the dicing tape T by a suction means not shown in the drawing (wafer holding step). Therefore, the half that is held on the work chuck 36 across the dicing tape T The conductor wafer 10 has the surface 120a of the functional layer 120 as the upper side.

As described above, after the semiconductor wafer 10 is attracted and held on the work chuck 36 via the dicing tape T, the control means 8 operates the feed means 37 to position the work chuck 36 holding the semiconductor wafer 10 to the image. Just below the means 6. After positioning the work chuck 36 directly below the image pickup means 6 as described above, the control means 8 activates the image pickup means 6 to perform a calibration operation for detecting the processing area of the semiconductor wafer 10 for laser processing. That is, the imaging means 6 and the control means 8 perform the divisional line 121 for forming the predetermined direction in the semiconductor wafer 10, and the laser beam irradiation means 5 for illuminating the laser beam along the division line 121. The aligning pattern of the concentrator 52 matches the image processing of the image, and the calibration of the laser beam irradiation position is completed. Further, the alignment of the laser beam irradiation position is similarly performed on the division planned line 121 which is formed on the semiconductor wafer 10 and which extends in the direction perpendicular to the predetermined direction.

When the above-described calibration step has been carried out, the control means 8 actuates the machining feed means 37 to move the working chuck 36 to the ray of the concentrator 52 of the laser beam irradiation means 5 as shown in Fig. 8(a). The light irradiation area is irradiated, and the predetermined division planned line 121 is positioned directly under the concentrator 52. At this time, as shown in FIG. 8(a), the semiconductor wafer 10 is positioned such that it is located at the position of 1 mm inside the one end (the left end in FIG. 8(a)) of the dividing line 121 at the position of the concentrator 52. Below. Then, the control means 8 activates the condensed spot position adjusting means not shown, and positions the concentrator 52 so that the condensed spot of the wavelength of 800 nm in the pulsed laser ray becomes the surface position of the dividing line 121.

Then, the control means 8 will actuate the pulse laser oscillating means The scan motor 530 is also actuated to rotate the scan mirror 53 at a predetermined rotational speed. As a result, from the concentrator 52 of the laser beam irradiation means 5 to the semiconductor wafer 10, the pulsed laser beam is irradiated in the X-axis direction within 2 mm of LB1 to LBn (laser processing groove forming step). . On the other hand, the control means 8 operates the machining depth detecting means 7 to detect the depth of the laser machining groove processed by the irradiation of the pulsed laser beams LB1 to LBn. The line sensor 763 of the processing depth detecting means 7 displays the light intensity at the wavelength of 800 nm as the highest value at the start of the processing, and the wavelength at which the light intensity is the highest value as the processing progresses is close to 900 nm. Then, when the depth of the processed laser processing groove is set to 30 μm, the wavelength to be the control reference is set to 860 nm from the control chart shown in FIG. 5 . Therefore, when the wavelength from the line image sensor 763 has been set to 860 nm, the control means determines that the depth of the laser processing groove has reached 30 μm, and operates the feed means 37. The work chuck 36 is moved by 2 mm in the direction indicated by the arrow X1 in Fig. 8(a) (feeding step).

The above-described laser processing groove forming step and feeding step are repeatedly performed, and the other end (the right end in FIG. 8(b)) of the division planned line 121 is positioned in the concentrator 52 as shown in FIG. 8(b). After the above-described laser processing groove forming step is performed at the position directly below, the control means 8 applies an RF (radio frequency) of a predetermined frequency to the optical axis changing means 54 composed of the acousto-optic element (AOD). The optical axis of the pulsed laser beam LB is directed toward the laser beam absorbing means 55, thereby stopping the irradiation of the laser light to the semiconductor wafer 10 held on the working chuck 36, and stopping the operation of the processing feed means 37 to stop. The movement of the work table 36. As a result, a semiconductor wafer 10 is formed. As shown in FIG. 8(c), the laser processing groove 120 is deeper than the thickness of the functional layer 120, that is, the laser processing groove 130 having a depth of 30 μm reaching the substrate 110, and the metal film 123 is removed and the functional layer 120 is broken. Then, the above-described laser processing groove forming step and feeding step are performed along all the dividing planned lines 121 formed on the semiconductor wafer 10.

Further, the laser processing groove forming step can be performed by, for example, the following processing conditions.

Laser light wavelength: 355nm (YAG laser)

Average output: 10W

Repeat frequency: 10MHz

As described above, the laser processing groove forming step in the illustrated embodiment detects the depth of the laser processing groove by the processing depth detecting means 7 while irradiating the pulsed laser beam along the dividing line 121, and After the laser processing groove reaches a predetermined thickness, the optical axis changing means 54 is actuated to direct the optical axis of the pulsed laser beam LB toward the laser beam absorbing means 55 to stop the pulsed laser beam from being held on the working chuck 36. Since the semiconductor wafer 10 is irradiated, even in the case where a plurality of metal films 123 for testing are partially disposed on the division planned line 121, a uniform depth can be formed without controlling the output of the pulsed laser light. Laser processing groove.

As described above, the semiconductor wafer 10 which has been separated by the laser processing groove 130 formed along the division planned line 121 is transferred to the dividing step, and is separated along the functional layer 120. The division planned line 121 performs division.

36‧‧‧Working table

5‧‧‧Laser light exposure

51‧‧‧Pulse laser oscillating means

511‧‧‧pulse laser ray oscillator

512‧‧‧Repetition frequency setting means

52‧‧‧ concentrator

521‧‧‧fθ lens

53‧‧‧Scan mirror

530‧‧‧Scan motor

53a‧‧‧arrow

54‧‧‧ Optical axis change means

55‧‧‧Laser light absorption means

7‧‧‧Processing depth detection means

71‧‧‧Check the light source

72‧‧‧chromatic aberration lens

73‧‧‧ Reflected light detection path

74‧‧‧beam splitter

75‧‧‧ Wavelength screening

751‧‧‧ Concentrating lens

752‧‧‧ pinhole mask

752a‧‧‧ pinhole

753‧‧‧ Collimating lens

76‧‧‧ Wavelength detection means

761‧‧‧diffraction grating

762‧‧‧ concentrating lens

763‧‧‧Line image sensor

LB, LB1, LBn‧‧‧ pulsed laser light

W‧‧‧Processed objects

Claims (1)

A laser processing apparatus is a laser processing apparatus including a workpiece holding means for holding a workpiece and a laser beam irradiation means for irradiating the laser beam onto the workpiece held by the workpiece holding means The laser light irradiation means is composed of the following: a pulsed laser ray oscillating means for oscillating to generate a pulsed laser beam; a concentrator for pulsing a pulsed ray which is oscillated from the pulsed laser oscillating means The illuminating light is condensed and irradiated onto the workpiece held by the workpiece holding means; and the scanning mirror is disposed between the pulsed laser ray oscillating means and the concentrator, and the laser light from the pulse is The pulsed laser beam oscillated by the oscillating means is guided to the concentrator, and has a processing depth detecting means for detecting a processing depth of the workpiece held by the workpiece holding means, and the processing depth detecting means It is constituted by: inspecting a light source, emitting inspection light having a predetermined wavelength band toward the scanning mirror; a color difference lens disposed at the inspection light source and the scanning And splitting the light according to the wavelength of the inspection light, and slightly changing the expansion angle of the inspection light for each wavelength; the beam splitter is disposed between the inspection light source and the color difference lens, and is emitted from the inspection light source. The scanning mirror and the concentrator irradiation The reflected light of the inspection light on the workpiece held by the workpiece holding means branches to the reflected light detection path; the wavelength screening means is disposed on the reflected light detection path so that the wavelength band of the reflected light can be The reflected light of the inspection light having a wavelength matching the focus of the workpiece passes; the wavelength detecting means detects the wavelength of the reflected light of the inspection light that has passed through the wavelength screening means; and the control means detects the wavelength detection means The wavelength of the workpiece is the depth of processing of the workpiece held by the workpiece holding means.