TWI660802B - Laser processing device - Google Patents

Abstract

An object of the present invention is to provide a laser processing device capable of forming a laser processing groove having a uniform depth without controlling the output of laser light. The solution is a laser processing device including a workpiece holding unit that holds a workpiece, and a laser beam irradiation unit that irradiates laser beams to the workpiece held by the workpiece holding unit. The laser light irradiation component is composed of a pulsed laser light oscillating component, a concentrator that focuses the pulsed laser light, and is arranged between the pulsed laser light oscillating component and the concentrator, and The pulsed laser light generated by the oscillation is scanned and guided to the scanning mirror of the condenser. A processing depth detection module is provided to detect the processing depth of the processing object held by the processing object holding module. The processing depth detection component is composed of: an inspection light source, which emits inspection light having a predetermined wavelength band toward a scanning mirror; a chromatic aberration lens, which is arranged between the inspection light source and the scanning mirror, and splits light according to the wavelength of the inspection light, The divergence angle of the inspection light is slightly changed for each wavelength; the beam splitter is arranged between the inspection light source and the chromatic aberration lens, and divides the reflected light of the inspection light irradiated on the processed object onto the reflected light detection path; the wavelength A screening component is arranged on the reflected light detection path to allow the reflected light of a wavelength consistent with the processed object to pass through the focal point; the wavelength detection component detects the wavelength of the reflected light that has passed through the wavelength screening component; and a control component, according to the wavelength The processing depth of the workpiece is determined by the wavelength detected by the detection unit.

Description

Laser processing device Field of invention

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

Background of the invention

In the manufacturing process of a semiconductor device, a plurality of regions are divided on a surface of a semiconductor wafer having a substantially circular plate shape by a predetermined division line arranged in a grid shape, and ICs, LSIs, and the like are formed in the divided regions. Device. In addition, the semiconductor wafer is cut along a street to divide a region where the device is formed, thereby manufacturing individual semiconductor devices.

Recently, in order to improve the processing capacity of semiconductor wafers such as ICs and LSIs, semiconductor wafers in the form of semiconductor devices are formed by functional layers on the surface of substrates such as silicon. The functional layers are made of SiOF, BSG (SiOB ) And other inorganic materials, or low dielectric constant insulator coatings (Low-k films) made of organic materials such as polyimide and parylene polymer films. Laminated.

Dividing along the dicing path of such a semiconductor wafer is usually performed by a cutting device called a dicer. This cutting device is provided with a work chuck for holding a semiconductor wafer as a workpiece, and is used for cutting. A cutting unit for cutting a semiconductor wafer held on the work chuck, and a moving unit that moves the work chuck and the cutting unit relatively. The cutting assembly includes a rotating main shaft that rotates at a high speed, and a cutting tool installed on the main shaft. The cutting blade is composed of a disc-shaped abutment and an annular cutting edge mounted on the outer peripheral portion of the side surface of the abutment. The cutting edge is formed by electroforming to fix diamond abrasive grains having a particle diameter of about 3 μm, for example .

However, it is difficult to cut the low-k film with a cutter. That is, since the Low-k film is very brittle like mica, when the cutting is performed along a predetermined dividing line with a cutter, the Low-k film peels off, and even the peeling reaches the circuit, causing the device to be fatal. The problem of damage.

In addition, in a semiconductor wafer configured with a test metal film called a test element group (TEG) for testing a device function in a functional layer on a predetermined division line, the following problems may occur: After the cutting blade cuts, burrs are generated and the quality of the device is reduced, and dressing of the cutting blade must be frequently performed to reduce productivity.

In order to solve the above-mentioned problems, Patent Document 1 below discloses a method for dividing a wafer by irradiating a laser beam along a predetermined division line formed on a semiconductor wafer to thereby divide a low-k film. A laser processing groove is formed on the formed multilayer body to separate the functional layer, and the cutting blade and the semiconductor wafer are relatively moved by positioning the cutter on the laser processing groove that has been separated from the functional layer, so as to The semiconductor wafer is cut along a predetermined division line.

However, a test metal called a test element group (TEG), which is provided with a device function for testing a function in a functional layer on a division predetermined line, In the film semiconductor wafer, there is a problem in that a laser processing trench having a uniform depth cannot be formed along a predetermined division line. In order to solve this problem, the following technology has been disclosed in Patent Document 2 below: detecting and disposing an area where a metal film for testing is arranged to create and store coordinates, and adjusting the output of laser light while dividing along the stored coordinates while dividing The predetermined line radiates laser light.

Prior art literature Patent literature

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

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

Summary of invention

However, in order to detect a region where a test metal film is arranged to make a coordinate like the technique disclosed in the aforementioned Patent Document 2, there is a problem that it takes a lot of time to deteriorate productivity, and it is necessary to control the coordinate mine in a timely manner according to the coordinate The output of the ray is not necessarily easy.

The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is to provide a laser processing device capable of forming a laser processing groove having a uniform depth without controlling the output of laser light.

In order to solve the above-mentioned main technical problems, a laser processing apparatus provided according to the present invention includes a workpiece holding unit for holding a workpiece, and a workpiece held by irradiating laser light onto the workpiece holding unit. Laser processing device for laser light irradiating component on object, characterized in The laser light irradiation component is composed of the following: a pulsed laser light oscillating component that oscillates to generate pulsed laser light; and a condenser that condenses the pulsed laser light generated from the pulsed laser ray oscillation component Light is irradiated on the workpiece held by the workpiece holding unit; and a scanning mirror is disposed between the pulse laser light oscillating unit and the condenser, and will receive the light from the pulse laser oscillating unit. The pulsed laser light generated by the oscillation is scanned and guided to the condenser, and is provided with a processing depth detection component that detects the processing depth of the processing object held by the processing object holding component. The processing depth detection component is composed of It is constituted as follows: an inspection light source emits inspection light having a predetermined wavelength band toward the scanning mirror; a chromatic aberration lens is arranged between the inspection light source and the scanning mirror, and splits light according to the wavelength of the inspection light, The wavelength of the divergence of the inspection light is slightly changed at each wavelength; a beam splitter is arranged between the inspection light source and the chromatic aberration lens, and is emitted from the inspection light source. The reflected light of the inspection light irradiated on the workpiece held by the workpiece holding unit through the scanning mirror and the condenser is diverged to the reflected light detection path; the wavelength screening component is arranged on the reflected light detection path In addition, in the wavelength band of the reflected light, the reflected light of the inspection light having a wavelength at which the object to be processed coincides with the focal point is passed; A wavelength detection component that detects the wavelength of the reflected light of the inspection light that has passed through the wavelength screening component; and a control component that determines, based on the wavelength detected by the wavelength detection component, the processing object held by the processing object holding component Processing depth.

The laser processing device of the present invention is configured as described above, and can operate the laser light irradiation module to irradiate the laser light onto the workpiece held by the workpiece holding module while detecting with the processing depth detection module. The depth of the processed laser processing groove, and once the laser processing groove reaches a predetermined thickness, the irradiation of laser light toward the workpiece is stopped, so even if there are different types of materials on the workpiece, A laser processing groove having a uniform depth is formed without controlling the output of the laser light. Therefore, it is not necessary to detect areas where different kinds of materials exist to make coordinates, so productivity can be improved.

10‧‧‧Semiconductor wafer

110‧‧‧ substrate

110a‧‧‧ surface

110b‧‧‧ lower surface

120‧‧‧Function layer

120a‧‧‧ surface

121‧‧‧ divided scheduled line

122‧‧‧Device

123‧‧‧metal film

130‧‧‧laser processing trench

2‧‧‧ static abutment

3‧‧‧Work clamp mechanism

31, 322‧‧‧rail

32‧‧‧1st slider

321, 331‧‧‧‧Guided trench

33‧‧‧ 2nd slider

34‧‧‧ cylindrical member

35‧‧‧Support

36‧‧‧Work clamp table

361‧‧‧ Suction Chuck

362‧‧‧Jig

37‧‧‧Processing feed assembly

371, 381‧‧‧ male screw

372, 382‧‧‧pulse motor

373, 383‧‧‧bearing block

38‧‧‧ indexing feed assembly

4‧‧‧laser light irradiation unit

41‧‧‧ support member

42‧‧‧ Case

5‧‧‧laser light irradiation module

51‧‧‧Pulse laser light oscillating component

511‧‧‧pulse laser oscillator

512‧‧‧Repetition frequency setting component

52‧‧‧Condenser

521‧‧‧fθ lens

53‧‧‧scanning mirror

530‧‧‧Scan motor

53a‧‧‧arrow

54‧‧‧ Optical axis change kit

55‧‧‧laser light absorbing component

6‧‧‧ camera module

7‧‧‧Processing depth detection module

71‧‧‧Check the light source

72‧‧‧ chromatic aberration lens

73‧‧‧Reflected light detection path

74‧‧‧ Beam Splitter

75‧‧‧wavelength screening module

751‧‧‧ condenser lens

752‧‧‧ pinhole mask

752a‧‧‧ pinhole

753‧‧‧Collimating lens

76‧‧‧wavelength detection module

761‧‧‧diffraction grating

762‧‧‧ condenser lens

763‧‧‧Linear image sensor

8‧‧‧Control component

81‧‧‧Central Processing Unit (CPU)

82‧‧‧Read Only Memory (ROM)

83‧‧‧ Random Access Memory (RAM)

84‧‧‧Input interface

85‧‧‧ output interface

F‧‧‧ Circular Frame

LB, LB1, LBn‧‧‧ pulse laser light

T‧‧‧Cutting Tape

W‧‧‧Processed

X, X1, Y, Z‧‧‧ directions

P1, P2‧‧‧ Spotlight

FIG. 1 is a perspective view of a laser processing apparatus constructed in accordance with the present invention.

FIG. 2 is a block configuration diagram of a laser light irradiation component and a processing depth detection component provided on the laser processing device shown in FIG. 1. FIG.

FIG. 3 is an explanatory diagram showing the light-condensing points of each wavelength of the inspection light of the processing depth detection module shown in FIG. 2.

FIG. 4 is a block configuration diagram of a control unit equipped on the laser processing apparatus shown in FIG. 1. FIG.

Figure 5 shows the relationship between the wavelength (nm) of inspection light and the processing depth (μm). Control chart.

6 (a) and 6 (b) are a perspective view and an enlarged cross-sectional view of a main part 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 a dicing tape mounted on a ring frame.

8 (a) to (c) are explanatory diagrams of a laser processing groove forming step and a feeding step performed by the laser processing apparatus shown in FIG. 1.

Forms used to implement the invention

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

FIG. 1 is a perspective view of a laser processing apparatus constructed in accordance with the present invention. The processing apparatus shown in FIG. 1 is provided with a stationary base 2 and a work clamp arranged so as to be movable on the stationary base 2 in a machining feed direction (X-axis direction) indicated by an arrow X and holding a workpiece. The table mechanism 3 and a laser light irradiation unit 4 as a laser light irradiation unit arranged on the base 2.

The work clamp 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 slide arranged on the guide rails 31 and 31 so as to be movable in the X-axis direction. Block 32. A second slider configured to be movable on the first slider 32 in an index feed direction (Y-axis direction) indicated by an arrow Y perpendicular to the processing feed direction (X-axis direction). 33. A support base 35 supported on the second slider 33 by a cylindrical member 34, and a work clamp 36 as a workpiece holding unit. This work chuck 36 is provided with a suction chuck 361 formed of a porous material, and is formed to be sucked by a suction not shown. The lead assembly holds, for example, a round semiconductor wafer, which is a workpiece, on a holding surface that is the upper surface of the suction chuck 361. The work clamp 36 configured as described above is rotated by a pulse motor (not shown) arranged in the cylindrical member 34. Furthermore, a jig 362 for fixing an annular frame is disposed on the work clamp table 36, and the annular frame supports a workpiece such as a semiconductor wafer through a protective tape.

The first slider 32 is provided on its lower surface with a pair of guided grooves 321 and 321 fitted into the pair of guide rails 31 and 31, and on its upper surface is provided with a parallel formed along the Y-axis direction. A pair of guide rails 322, 322. The first slide block 32 configured as described above is configured to fit the guided grooves 321 and 321 to the pair of guide rails 31 and 31 so that the pair of guide rails 31 and 31 can be moved along the X-axis direction. mobile. The work clamp mechanism 3 in the illustrated embodiment includes a processing feed unit 37 for moving the first slider 32 along the pair of guide rails 31 and 31 in the X-axis direction. The processing feed unit 37 includes a male screw 371 arranged 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. 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 driven and connected by the output shaft of the pulse motor 372. Furthermore, a male screw 371 is screwed into a through screw hole formed by a female screw block (not shown) provided to protrude from the lower surface of the central portion of the first slider 32. Therefore, by driving the male screw 371 forward and backward with the pulse motor 372, the first slide block 32 can be moved in the X-axis direction along the guide rails 31 and 31.

The second slider 33 is configured such that a pair of guide rails 322 and 322 provided on a lower surface of the second slider 33 can be fitted to the upper surface of the first slider 32. The pair of guided grooves 331 and 331 can be moved in the Y-axis direction by fitting the guided grooves 331 and 331 to a pair of guide rails 322 and 322. The work table mechanism 3 in the illustrated embodiment is provided with an index feeding unit for moving the second slider 33 along the pair of guide rails 322 and 322 mounted on the first slider 32 in the Y-axis direction. 38. The indexing feed unit 38 includes a male screw 381 disposed in parallel between the pair of guide rails 322 and 322, and a drive source such as a pulse motor 382 for rotationally driving the male screw 381. One end of the male screw 381 is rotatably supported by a bearing block 383 fixed on the upper surface of the first slider 32, and the other end is driven and connected by the output shaft of the pulse motor 382. Furthermore, a male screw 381 is screwed into a through screw hole formed by a female screw block (not shown) provided to protrude from the lower surface of the central portion of the second slider 33. Therefore, by driving the male screw 381 forward and reverse with 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 light irradiation unit 4 includes a support member 41 disposed on the base 2, a cover 42 supported by the support member 41 and extending substantially horizontally, and a laser light irradiation assembly disposed on the cover 42. 5. A camera module 6 disposed at the front end of the casing 42 and capable of detecting a processing area for laser processing. Furthermore, the camera module 6 is provided with a lighting module that illuminates the object to be processed, an optical system that captures an area illuminated by the lighting module, and a camera element (CCD) that captures an image captured by the optical system. The captured image signal is transmitted to a control unit described later.

The above-mentioned laser light irradiation unit 5 will be described with reference to FIG. 2.

The laser light irradiation unit 5 is composed of a pulsed laser light oscillating unit 51 and a pulsed laser light oscillated from the pulsed laser ray oscillating unit 51 to condense and hold the pulsed laser ray irradiated on the work clamp 36. The condenser 52 on the workpiece W and the laser light ray generated from the pulsed laser light oscillating unit 51 are guided and guided while being arranged between the pulsed laser light oscillating unit 51 and the condenser 52. To the scanning mirror 53 of the condenser 52. The pulsed laser light oscillating component 51 is composed of a pulsed laser light oscillator 511 and a repetition frequency setting component 512 attached thereto. Furthermore, in the implementation state shown in the figure, the pulsed laser light oscillator 511 of the pulsed laser light oscillating component 51 oscillates and generates a pulsed laser light LB having a wavelength of 355 nm. The condenser 52 includes an f θ lens 521 that condenses the pulsed laser beam LB generated by the pulsed laser beam oscillating unit 51. In addition, the condenser 52 is formed so that it can adjust the direction of the position of the light-condensing point perpendicular to the holding surface of the work clamp table 36 by a light-condensing point position adjusting assembly (not shown) (shown in FIG. (Z-axis direction shown by arrow Z).

The above-mentioned scanning mirror 53 is constituted by a polygon mirror in the illustrated embodiment, and the scanning motor 530 is rotated in a direction indicated by an arrow 53a in FIG. 2 to oscillate the component 51 from the pulsed laser light. The pulsed laser light LB generated by the oscillation is guided to the fθ lens 521 in the X-axis direction within a range of LB1 to LBn. A galvano-mirror can also be used as the scanning mirror 53. The range of the pulsed laser beams LB1 to LBn condensed by the f θ lens 521 is exaggerated and drawn in the illustrated embodiment, but can be set to, for example, 2 mm.

The laser beam irradiation unit 5 in the illustrated embodiment includes a pulse laser beam LB which is disposed between the pulse laser beam oscillating unit 51 and the scanning mirror 53 and oscillates from the pulse laser beam oscillating unit 51. Light The optical axis changing unit 54 whose axis is deflected. In the illustrated embodiment, this optical axis changing unit 54 is composed of an acousto-optic element (AOD), and when a predetermined frequency RF (radio frequency) is applied, it is shown as a dotted line in FIG. 2 The optical axis of the pulsed laser light LB is changed toward the laser light absorbing unit 55.

The pulsed laser beam oscillating unit 51, the scanning motor 530, and the optical axis changing unit 54 of the laser beam irradiating unit 5 configured as described above are controlled by a control unit described later.

2, the laser processing apparatus in the illustrated embodiment is provided with a processing depth detection module 7 that detects the processing depth of the workpiece W held by the work clamp 36 as a workpiece holding module. The processing depth detection module 7 includes an inspection light source 71, a chromatic aberration lens 72, a beam splitter 74, a wavelength screening module 75, and a wavelength detection module 76. The inspection light source 71 emits inspection light having a predetermined wavelength band toward the scanning mirror 53 of the laser light irradiation unit 5. The chromatic aberration lens 72 is arranged between the inspection light source 71 and the scanning lens 53 and splits the light according to the wavelength of the inspection light, and changes the divergence angle of the inspection light slightly for each wavelength. The beam splitter 74 is disposed between the inspection light source 71 and the chromatic aberration lens 72, and is emitted from the inspection light source 71 and passes through the scanning lens 53 and the f θ lens 521 of the condenser 52. The reflected light of the inspection light on the processed object W is branched onto the reflected light detection path 73. The wavelength screening unit 75 is disposed on the reflected light detection path 73 and allows reflected light of inspection light having a wavelength that is the same as that of the object to be processed in the wavelength band of the reflected light. The wavelength detection component 76 detects the wavelength of the reflected light of the inspection light that has passed through the wavelength screening component 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 separates the inspection light having a wavelength band of 800 to 900 nm emitted by the inspection light source 71 into the corresponding wavelength, and guides the divergence angle of the inspection light to the scanning mirror 53 by slightly changing the divergence angle for each wavelength. Therefore, the inspection light having a wavelength band of 800 to 900 nm, which is reflected on the scanning mirror 53 and guided to the fθ lens 521, will form 800 nm light at P1 as shown in FIG. 3, and the wavelength will be The 900 nm light is focused on P2. In the illustrated embodiment, the distance between the light-condensing point P1 having a wavelength of 800 nm and the light-condensing point P2 having a wavelength of 900 nm is set to 50 μm. Therefore, in the embodiment shown in the figure, a control chart 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 chart is stored in the memory of the control unit described later. in.

Although the above-mentioned beam splitter 74 directs the inspection light having a wavelength band of 800 to 900 nm emitted by the inspection light source 71 to pass through the chromatic aberration lens 72, the reflected light of the inspection light that has been irradiated on the work clamp table 36 will reflect toward The light detection path 73 diverges. The wavelength screening unit 75 disposed on the reflected light detection path 73 is a pinhole mask including a condensing lens 751 and a pinhole mask 751 which is arranged at a focal position of the condensing lens 751 on the downstream side of the condensing lens 751. 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 into parallel light. The wavelength screening unit 75 configured as described above is a needle formed so that the reflected light of the wavelength reflected by the inspection light irradiated on the workpiece W held by the work clamp table 36 at the condensing point can pass through the pinhole mask 752. Hole 752a. The wavelength detection component 76 is composed of a diffraction grating 761, A condenser lens 762 and a linear image sensor 763 are formed. The diffraction grating 761 diffracts the reflected light formed as parallel light by the collimator lens 753 and transmits the diffraction signal corresponding to each wavelength to the linear image sensor 763 through the condenser lens 762. The linear image sensor 763 detects the light intensity in each wavelength of the reflected light diffracted by the diffraction grating 761 and transmits a detection signal to a control unit described later.

The laser processing apparatus in the illustrated embodiment includes a control unit 8 shown in FIG. 4. The control unit 8 is composed of a computer, and includes a central processing unit (CPU) 81 that performs calculation processing according to a control program, a read-only memory (ROM) 82 that stores a control program, and the like, which can be read and written. Random access memory (RAM) 83, input interface 84, and output interface 85. The input interface 84 of the control unit 8 is input with detection signals from the camera unit 6, the linear image sensor 763, and the like. Then, the control signal is output from the output interface 85 of the control module 8 to the above-mentioned processing feed module 37, indexing feed module 38, pulse laser light oscillation module 51, scanning motor 530 of the scanning mirror 53, and the optical axis. The change unit 54, the inspection light source 71 of the processing depth detection unit 7, and the like. The random access memory (RAM) 83 stores a control chart showing the relationship between the wavelength (nm) of the inspection light and the processing depth (μm) shown in FIG. 5.

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

(A) and (b) of FIG. 6 are a perspective view and an enlarged sectional view of a main part of a semiconductor wafer as a workpiece.

The semiconductor wafer 10 shown in (a) and (b) of FIG. 6 is a functional layer formed by laminating an insulating film and a functional film forming a circuit on a surface 110a of a substrate 110 such as silicon having a thickness of 150 μm. 120, and devices 122 such as ICs and LSIs are formed on the functional layer 120 in a plurality of areas divided by a plurality of predetermined division lines 121 formed in a grid pattern. Furthermore, in the illustrated embodiment, the insulating film forming the functional layer 120 is a SiO ₂ film, a film of an inorganic substance such as SiOF, BSG (SiOB), or a polyimide 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 and the like is formed, and the thickness is set to 10 μm. In addition, a plurality of test metal films 123 called test element groups (TEG) for testing the functions of the device 122 are partially arranged on the planned division line 121 of the semiconductor wafer 10, and the test metal film 123 is It is made of copper (Cu) and aluminum (Al).

When the semiconductor wafer 10 is processed along a predetermined division line, a wafer supporting step of attaching the semiconductor wafer 10 to a dicing tape mounted on a ring frame is performed. That is, as shown in FIG. 7, the back surface 110 b of the substrate 110 constituting the semiconductor wafer 10 is attached to a ring frame F and is formed by a synthetic resin sheet such as polyolefin. On the surface of the tape T. Therefore, in the semiconductor wafer 10 attached to the surface of the dicing tape T, the surface 120 a of the functional layer 120 is positioned on the upper side.

After the wafer supporting step has been performed, the dicing tape T side of the semiconductor wafer 10 can be placed on the work clamp table 36 of the laser processing apparatus shown in FIG. 1. Then, a suction unit (not shown) is operated to suck and hold the semiconductor wafer 10 on the work clamp table 36 via the dicing tape T (wafer holding step). Therefore, the half held on the work clamp table 36 across the cutting tape T The conductive wafer 10 has the surface 120 a of the functional layer 120 on the upper side.

As described above, after the semiconductor wafer 10 is attracted and held on the work clamp table 36 via the dicing tape T, the control module 8 operates to process the feed module 37 to position the work clamp table 36 holding the semiconductor wafer 10 to the camera. Module 6 is directly below. After the work clamp 36 is positioned directly below the camera module 6 in this manner, the control module 8 operates the camera module 6 to perform a calibration operation for detecting a processing area of the semiconductor wafer 10 for laser processing. That is, the camera module 6 and the control module 8 execute a planned division line 121 for forming a predetermined direction of the semiconductor wafer 10 and a laser light irradiation unit 5 configured to irradiate laser light along the predetermined division line 121. The image matching of the alignment pattern of the concentrator 52 and other image processing are performed to complete the calibration of the laser light irradiation position. In addition, the alignment of the laser light irradiation position is similarly completed for the predetermined division line 121 formed on the semiconductor wafer 10 and extending in a direction perpendicular to the predetermined direction.

After the above calibration steps have been performed, the control module 8 will operate the processing feed module 37 to move the work clamp 36 to the mine where the condenser 52 of the laser light irradiation module 5 is located as shown in FIG. 8 (a). The light rays irradiate the area, and a predetermined division-predetermined line 121 is positioned directly below the condenser 52. At this time, as shown in FIG. 8 (a), the semiconductor wafer 10 is positioned so that a position 1 mm inward of one end (the left end in FIG. 8 (a)) of the planned division line 121 is positioned at the positive side of the condenser 52. Below. Then, the control unit 8 operates a condensing point position adjusting unit (not shown) to position the concentrator 52 so that the condensing point having a wavelength of 800 nm in the pulsed laser light becomes the surface position of the division line 121.

Next, the control unit 8 activates the pulsed laser light oscillating unit. 51 and actuates the scanning motor 530 to rotate the scanning mirror 53 at a predetermined rotation speed. As a result, from the condenser 52 of the laser light irradiation module 5 to the semiconductor wafer 10, the pulsed laser light is irradiated in the X-axis direction within a range of 2 mm from LB1 to LBn (laser processing groove forming step) . On the other hand, the control unit 8 activates the processing depth detection unit 7 to detect the depth of the laser processing groove processed by the irradiation of the pulse laser light LB1 to LBn. At the start of processing, the linear sensor 763 of the processing depth detection module 7 displays the light intensity at a wavelength of 800 nm as the highest value, and the wavelength at which the light intensity is the highest value approaches 900 nm as the processing progresses. Then, when the depth of the laser-processed groove to be processed 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 of the highest light intensity has been formed to 860 nm according to the detection signal from the linear image sensor 763, the control module judges that the depth of the laser processing groove has reached 30 μm, and operates the processing feed module 37 to The work clamp table 36 is moved 2 mm in the direction shown by the arrow X1 in Fig. 8 (a) (feeding step).

Repeat the laser processing groove forming step and the feeding step described above, and place the other end of the planned division line 121 (the right end in FIG. 8 (b)) on the condenser 52 as shown in FIG. 8 (b). After the laser processing groove forming step has been performed, the control unit 8 applies a predetermined frequency RF (radio frequency) to the optical axis changing unit 54 composed of an acousto-optic element (AOD). The optical axis of the pulsed laser light LB is directed toward the laser light absorbing component 55, so as to stop the laser light from irradiating the semiconductor wafer 10 held on the work clamp table 36, and stop the operation of the processing feed module 37 to stop. Movement of the work clamp table 36. As a result, a semiconductor wafer 10 is formed. As shown in FIG. 8 (c), the depth is deeper than the thickness of the functional layer 120, that is, the laser processing groove 130 reaching the substrate 110 to a depth of 30 μm, the metal film 123 is removed, and the functional layer 120 is divided. Then, the laser processing groove forming step and the feeding step described above are performed along all of the planned division lines 121 formed on the semiconductor wafer 10.

The laser processing groove forming step can be performed under the following processing conditions, for example.

Laser light wavelength: 355nm (YAG laser)

Average output: 10W

Repetition frequency: 10MHz

As described above, the laser processing groove forming step in the illustrated embodiment is to detect the depth of the laser processing groove by the processing depth detection unit 7 while irradiating pulse laser light along the predetermined division line 121, and After the laser processing groove reaches a predetermined thickness, the optical axis changing component 54 is operated to direct the optical axis of the pulsed laser light LB toward the laser light absorbing component 55 to stop the pulsed laser light from being held on the work clamp 36. Since the semiconductor wafer 10 is irradiated, even in the case where a plurality of test metal films 123 are partially arranged on the predetermined division line 121, a uniform depth can be formed without controlling the output of the pulsed laser light. Laser processing trench.

As described above, the semiconductor wafer 10 having the functional layer 120 divided by the laser processing trench 130 formed along the predetermined division line 121 is transferred to the dividing step, and the functional layer 120 has been divided. The division line 121 is divided.

Claims (1)

A laser processing device includes a workpiece holding unit that holds a workpiece, and a laser light irradiation unit that irradiates laser light onto a workpiece that is held by the workpiece holding unit. The device is characterized in that the laser light irradiation component is composed of: a pulsed laser light oscillating component that oscillates to generate a pulsed laser light; and a condenser that oscillates a pulsed laser generated from the pulsed laser light oscillating component. The light is focused and irradiated on the workpiece held by the workpiece holding component; and a scanning mirror is disposed between the pulse laser light oscillating component and the condenser, and oscillates from the pulse laser light The pulsed laser light generated by the component is scanned and guided to the condenser, and the laser processing device is provided with a processing depth detection component that detects a processing depth of the processing object held by the processing object holding component. The processing depth detection component is composed of: an inspection light source, which emits inspection light having a predetermined wavelength band toward the scanning mirror; and a chromatic aberration lens disposed at the Between the inspection light source and the scanning lens, the light is split according to the wavelength of the inspection light, and the divergence angle of the inspection light is slightly changed for each wavelength; the beam splitter is arranged between the inspection light source and the chromatic aberration lens, and The reflected light of the inspection light emitted from the inspection light source and irradiated through the scanning lens and the condenser on the workpiece held by the workpiece holding component is diverged to the reflected light detection path; the wavelength screening component is configured On the reflected light detection path, the reflected light of the inspection light having the wavelength at which the processed object coincides with the focal point is passed in the wavelength band of the reflected light; the wavelength detection component detects the reflection of the inspection light that has passed through the wavelength screening component. A wavelength of light; and a control unit that obtains a processing depth of the workpiece held by the workpiece holding unit based on the wavelength detected by the wavelength detection unit.