TW201637084A - Wafer processing method - Google Patents

Abstract

To provide a wafer processing method which can prevent the peeling of functional layer on a wafer to form devices on plural regions partitioned by plural predetermined division lines formed on the functional layer laminated on the substrate surface in a grid-like shape, can prevent the generation of pores or cracks of substrate, and can proceed division along the predetermined division lines. The wafer processing method is a method to process the wafer formed with devices on plural regions partitioned by plural predetermined division lines formed on the functional layer laminated on the substrate surface in a grid-like shape. It comprises: a convex strip forming engineering, i.e. along the predetermined parting line formed on the wafer, configure the determined spacing and irradiate laser light, so that the functional layer bulges along the predetermined parting line, thereby forming two convex strips; and a division engineering to divide the wafer embodied with the convex strip forming engineering along the region sandwiched between two convex strips.

Description

Wafer processing method

The present invention relates to a method of processing a wafer in which a wafer of a device is formed by a functional layer laminated on a surface of a substrate such as tantalum along a predetermined dividing line.

In the semiconductor device manufacturing process, a plurality of regions are divided by a predetermined dividing line which is arranged in a lattice shape on the surface of the semiconductor wafer having a substantially circular plate shape, and devices such as ICs and LSIs are formed in the regions of the regions. Then, each semiconductor device is manufactured by cutting the semiconductor wafer along a predetermined dividing line and dividing the region where the device is formed.

Recently, in order to improve the processing capability of a semiconductor wafer such as an IC or an LSI, an inorganic film such as SiO ₂ , SiOF or BSG (SiOB) and a polyimide group are aggregated by a surface of a substrate such as ruthenium or the like. A functional layer of a low dielectric constant insulator film (Low-k film) formed of a film of an organic film such as a p-xylene system or the like is used as a semiconductor wafer in a form of a semiconductor device.

The division of such a semiconductor wafer along a predetermined dividing line is usually performed by a cutting device called a cutting machine. The cutting device A chucking device for holding a semiconductor wafer as a workpiece, a cutting means for cutting a semiconductor wafer held by the chucking table, and a moving means for moving the chucking table and the cutting means. The cutting means includes a rotating spindle that rotates at a high speed and a cutter that is attached to the spindle. The cutting blade is formed of a disk-shaped base and an annular blade attached to the outer peripheral portion of the side surface of the base. The blade is formed by plating, for example, diamond abrasive grains having a particle diameter of about 3 μm.

However, the above Low-k film is difficult to cut by a cutter. That is, since the Low-k film is very fragile like mica, and the cutting is performed along the predetermined dividing line by the cutter, the Low-k film peels off, and the peeling reaches the circuit, which causes a fatal damage to the device.

In order to eliminate the above problem, Patent Document 1 described later discloses that a laser beam having a wavelength that is absorptive to a functional layer is irradiated along a predetermined dividing line formed on a semiconductor wafer, and a laser processing groove is formed along a predetermined dividing line. The functional layer is removed, and the cutting blade is positioned in the laser processing groove to relatively move the cutting blade and the semiconductor wafer, thereby cutting the semiconductor wafer by a predetermined dividing line.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-21476

Then, by illuminating the wave that is absorptive to the functional layer When a long laser beam is formed along a predetermined dividing line to form a laser processing groove and the functional layer is removed, the laser light from which the functional layer is removed is irradiated onto a semiconductor substrate such as a germanium substrate or a gallium nitride substrate, and the semiconductor substrate is damaged. The pores or cracks of the starting point have a problem of causing a decrease in the bending strength of the device.

The present invention has been made in view of the above-described facts, and its main technical object is to provide a wafer which does not allow a plurality of region forming devices which are formed by a plurality of predetermined dividing lines formed in a functional layer laminated on a surface of a substrate in a lattice shape. The method in which the functional layer is peeled off and the substrate is not subjected to voids, cracks, or the like, and the wafer can be divided along the predetermined dividing line.

In order to solve the above-described main technical problems, according to the present invention, there is provided a method of processing a wafer, which is formed by forming a plurality of regions defined by a plurality of predetermined dividing lines of a functional layer laminated on a surface of a substrate in a lattice shape. A method for processing a wafer of a device, comprising: a rib forming process, wherein a predetermined interval is formed along a predetermined dividing line formed on the wafer, and the laser beam is irradiated to cause the functional layer to bulge along the predetermined dividing line. This forms two ridges; and the dividing process divides the wafers on which the ribs are formed along the area held by the two ribs.

In the aforementioned rib forming process, the output of the laser light is set to an output that only expands the functional layer.

The ridges form an output of the projecting laser light, and the energy per pulse of the laser beam is set to 4 to 10 nj.

Further, the distance between the dots and the dots of the laser light for forming the ridges is set to 4 to 8 nm.

In the above division process, the cutter is placed in a region held by two ridges to cut the wafer along a predetermined dividing line.

Further, in the division process, the laser beam is irradiated to the region held by the two ridges, and the wafer is cut along the predetermined dividing line.

The method for processing a wafer according to the present invention comprises: setting a predetermined interval along a predetermined dividing line formed on the wafer and irradiating the laser beam to bulge the functional layer along a predetermined dividing line, thereby forming two ridges The rib forming process and the division of the wafer for performing the ridge forming process are performed along the area held by the two ridges. Therefore, when performing the dicing process, the rib forming process is performed. The functional layer constituting the wafer is formed with two ridges along a predetermined dividing line. Therefore, the two ridges suppress the breaking force caused by the cutting of the cutting blade and the laser light from reaching the device side. The functional layer that is laminated on the device does not peel off and does not degrade the quality of the device.

2‧‧‧Semiconductor wafer

3‧‧‧ Laser processing equipment

31‧‧‧Sampling station for laser processing equipment

32‧‧‧Laser light exposure

324‧‧‧ concentrator

33‧‧‧Photography

4‧‧‧Cutting device

41‧‧‧Sucker table for cutting device

42‧‧‧ Cutting means

421‧‧‧ spindle housing

422‧‧‧Rotating spindle

423‧‧‧Cutter

423a‧‧ arrow

424‧‧‧Abutment

425‧‧‧blade

43‧‧‧Photography

F‧‧‧Ringed frame

T‧‧‧ cutting tape

Fig. 1 is a perspective view and a cross-sectional view of an essential part of a semiconductor wafer as a wafer processed by the method for processing a wafer according to the present invention.

[Fig. 2] discloses that the semiconductor wafer shown in Fig. 1 is bonded and mounted on A perspective view of the state of the surface of the dicing tape of the annular frame.

Fig. 3 is a perspective view of a principal part of a laser processing apparatus for performing a ridge forming process for a wafer processing method according to the present invention.

Fig. 4 is a block configuration diagram of a laser beam irradiation means equipped in the laser processing apparatus shown in Fig. 3.

Fig. 5 is an explanatory view showing a ridge forming process of a wafer processing method according to the present invention.

Fig. 6 is a block diagram showing another embodiment of a concentrator constituting a laser beam irradiation means provided in the laser processing apparatus shown in Fig. 3.

Fig. 7 is a perspective view of a principal part of a cutting device for cutting work as a division process for carrying out a method for processing a wafer according to the present invention.

Fig. 8 is an explanatory view showing a cutting process as a dividing project in the method for processing a wafer by the present invention.

Fig. 9 is an explanatory view showing a laser processing groove forming process as a division process of the wafer processing method by the present invention.

Hereinafter, a preferred embodiment of the method for processing a wafer according to the present invention will be described in detail with reference to the accompanying drawings.

1(a) and 1(b) are a perspective view and an enlarged cross-sectional view of an essential part of a semiconductor wafer as a wafer. The semiconductor wafer 2 shown in (a) and (b) of FIG. 1 is formed on a surface 20a of a substrate 20 having a thickness of, for example, 100 μm, and a functional layer 21 in which a functional film of a laminated insulating film and a circuit is formed, and A device 212 such as an IC or an LSI is formed in a plurality of regions defined by a plurality of predetermined dividing lines 211 formed in a lattice shape on the functional layer 21. In the embodiment shown in the drawings, the insulating film forming the functional layer 21 is made of an SiO ₂ film, an inorganic film such as SiOF or BSG (SiOB), a polyimide, a polyparaxylene or the like. The polymer film was formed of a low dielectric constant insulator film (Low-k film) made of an organic film, and the thickness was set to 10 μm. Further, the width of the predetermined dividing line 211 is set to 50 μm in the illustrated embodiment.

For dividing the semiconductor wafer 2 described above along the predetermined dividing line 211, first, the dicing tape is bonded to the back surface of the substrate 20 constituting the semiconductor wafer 2, and the outer peripheral portion of the dicing tape is supported by an annular frame. Wafer support engineering. In other words, as shown in FIG. 2, the surface of the dicing tape T of the outer peripheral portion is attached so as to cover the inner opening portion of the annular frame F, and the back surface 20b of the substrate 20 constituting the semiconductor wafer 2 is bonded. Therefore, the semiconductor wafer 2 bonded to the surface of the dicing tape T has the upper surface 21a of the functional layer 21.

If the above-described wafer support engineering is carried out, a predetermined dividing line 211 formed on the semiconductor wafer 2 is disposed, a predetermined interval is set and the laser beam is irradiated, and the functional layer 21 is raised along the predetermined dividing line 211, thereby forming The ridges of the two ridges form a project. This ridge forming process is implemented using the laser processing apparatus 3 shown in FIG. The laser processing apparatus 3 shown in FIG. 3 includes a chuck table 31 for holding a workpiece, and a laser beam irradiation means 32 for irradiating a laser beam to a workpiece held on the chuck table 31, and the pair is held. The imaging means 33 for imaging the workpiece on the chuck table 31. The suction table 31 is configured to attract and hold the workpiece According to the machining feed means (not shown), the machining feed direction (X-axis direction) indicated by an arrow X in FIG. 3 is moved, and the feed means is indexed by an index (not shown). The index is indicated in the feed direction (Y-axis direction) by the index indicated by the arrow Y in FIG.

The laser light irradiation means 32 includes a cylindrical casing 321 that extends substantially horizontally. The laser light irradiation means 32 will be described with reference to Fig. 4 .

The illustrated laser beam irradiation means 32 includes a pulsed laser beam oscillating means 322 disposed in the casing 321 and an output of the pulsed laser beam LB oscillated by the pulsed laser beam oscillating means 322. The output adjustment means 323 adjusts the output pulsed laser beam by the output adjustment means 323 to the concentrator 324 of the workpiece W held by the holding surface of the chuck table 31.

The pulsed laser ray oscillating means 322 is composed of a pulsed laser ray 322a for oscillating the pulsed laser ray and a repetition frequency setting means 322b for repeating the frequency of the pulsed laser ray oscillated by the set pulsed laser ray oscillator 322a. Composition. Further, the pulsed laser ray oscillator 322a is oscillated in the illustrated embodiment to pulsing the pulsed laser beam LB having a wavelength of 355 nm.

The output adjustment means 323 adjusts the output of the pulsed laser ray oscillated from the pulsed laser ray oscillating means 322 to a predetermined output. The pulsed laser ray oscillator 322a, the repetition frequency setting means 322b, and the output adjustment means 323 of the pulsed laser beam oscillating means 322 are controlled by a control means not shown.

The concentrator 324 includes a direction conversion mirror 324a that oscillates the pulsed laser beam ray from the pulsed laser beam oscillating means 322 and adjusts the output by the output adjustment means 323, and performs direction switching toward the holding surface of the chuck table 31. The pulsed laser light that is converted by the direction changing mirror 324a is condensed and irradiated to the condensing lens 324b of the workpiece W held by the chuck table 31. The concentrator 324 thus constructed is attached to the casing 321 as shown in FIG.

Returning to FIG. 3, the imaging means 33 is attached to the front end portion of the casing 321 constituting the laser beam irradiation means 32. The imaging means 33 is constituted by an optical system such as a microscope, an imaging element (CCD) or the like, and sends an image signal of the imaging to a control means (not shown).

With respect to the use of the above-described laser processing apparatus 3, along a predetermined dividing line 211 formed on the semiconductor wafer 2, a predetermined interval is provided and the laser beam is irradiated, and the functional layer 21 is raised along the predetermined dividing line 211, thereby forming two The ridge forming process of the ridges will be described with reference to FIGS. 3 and 4.

First, the wafer support process described above is carried out, and the dicing tape T side of the semiconductor wafer 2 is placed on the chuck table 31. By operating the suction means (not shown), the semiconductor wafer 2 is sucked and held on the chuck table 31 via the dicing tape T (wafer holding process). Therefore, the semiconductor wafer 2 held by the chuck table 31 has the upper surface 21a of the functional layer 21. In addition, in FIG. 3, the frame F in which the ring shape of the dicing tape T is attached is abbreviate|omitted, and the frame|frame F of the cyclic|annular frame F is hold|maintained by the appropriate frame holding means arrange|positioned by the suction-plate holder 31. In this way, attracting and holding semiconductor wafers The suction table 31 of 2 is located directly below the imaging means 33 by a processing feed means (not shown).

When the chuck table 31 is located immediately below the image pickup unit 33, the image pickup means 33 and a control means (not shown) perform a calibration operation for detecting the processing area of the semiconductor wafer 2 to be subjected to laser processing. In other words, the imaging means 33 and the control means (not shown) perform a predetermined dividing line 211 for forming a predetermined direction of the semiconductor wafer 2, and a laser beam for irradiating the laser beam along the predetermined dividing line 211. The image processing such as pattern matching of the concentrating device 324 of the irradiation means 32 is performed to perform calibration (calibration work) of the laser beam irradiation position. Further, the predetermined dividing line 211 of the semiconductor wafer 2 is formed in a direction orthogonal to the predetermined direction, and the calibration of the laser light irradiation position is performed in the same manner.

When the calibration process described above is carried out, as shown in FIG. 3, the chuck table 31 is moved to the laser beam irradiation area where the concentrator 324 of the laser beam irradiation means 32 for irradiating the laser light is located, as shown in FIG. As shown in a), one end (the left end in FIG. 5(a)) formed at a predetermined predetermined dividing line 211 of the semiconductor wafer 2 is positioned so as to be located directly below the concentrator 324. At this time, positioning is performed so that the position from the center in the width direction of the predetermined dividing line 211 to one side, for example, 20 μm, is located immediately below the concentrator 324. Then, the condensed spot P of the pulsed laser beam LB irradiated from the concentrator 324 is positioned in the vicinity of the surface (upper surface) of the functional layer 21 of the predetermined dividing line 211. Next, while illuminating the pulsed laser beam set to output only the functional layer 21 from the concentrator 324 of the laser beam irradiation means 32, the chuck table 31 is shown by an arrow X1 in Fig. 5(a). direction Move at the machining feed speed. Then, as shown in FIG. 5(b), when the other end of the predetermined dividing line 211 (the right end in FIG. 5(b)) reaches the position directly below the concentrator 324, the irradiation of the pulsed laser light is stopped, and the stop is stopped. The movement of the suction pad table 31.

Next, the chuck table 31 is moved to a direction perpendicular to the paper surface (exponentially calibrated in the feed direction) by, for example, 40 μm. As a result, the positioning is performed so as to be located directly below the concentrator 324 from the center in the width direction of the predetermined dividing line 211 to the other side, for example, 20 μm. Then, as shown in FIG. 5(c), while the pulsed laser beam is irradiated from the concentrator 324 of the laser beam irradiation means 32, the chuck table 31 is moved at a predetermined machining feed speed in the direction indicated by the arrow X2. In the position shown in Fig. 5 (a), the irradiation of the pulsed laser light is stopped, and the movement of the chuck table 31 is stopped.

By performing the above-described ridge forming process, on the functional layer 21 of the semiconductor wafer 2, as shown in FIG. 5(d), two ridges 24, 24 which are swelled along the predetermined dividing line 211 are formed. Then, the above-described ridge forming process is performed along all predetermined dividing lines 211 formed on the semiconductor wafer 2.

Further, the above-described ridge forming process is performed under the following processing conditions.

Laser light wavelength: 355nm

Repeat frequency: 80MHz

Average output: 0.5W

Converging point diameter: φ10μm

Processing feed rate: 450mm / sec

Next, another embodiment of the concentrator 324 constituting the laser beam irradiation means 32 of the laser processing apparatus 3 for performing the above-described ridge forming process will be described with reference to FIG.

The concentrator 324 shown in FIG. 6 is disposed between the direction changing mirror 324a and the collecting lens 324b, and is provided with a pulsed laser beam that is converted by the direction changing mirror 324a in a direction different from the Y-axis direction. The difference means 324c. The concentrator 324 thus configured illuminates the pulsed laser beams LB1 and LB2 which are branched by the branching means 324c at a predetermined interval in the Y-axis direction. Therefore, by using the concentrator 324 shown in Fig. 6, two ridges bulging along a predetermined dividing line can be simultaneously formed. Further, when the concentrator 324 shown in Fig. 6 is used, the output of the pulsed laser beams LB1 and LB2 which are branched by the divergent means 324c becomes the pulsed laser beam LB which oscillates from the pulsed laser ray oscillating means 322. Since the output is 1/2, the average output of the pulsed laser beam LB oscillated from the pulsed laser beam oscillating means 322 in the above-described ridge forming process is set to 1.0 W.

When the above-described ridge forming process is carried out, the division process of the semiconductor wafer 2 is performed by dividing the region held by the two ridges 24, 24. The first embodiment of the division project is implemented using the cutting device 4 shown in Fig. 7 in the illustrated embodiment. The cutting device 4 shown in FIG. 7 includes a chuck table 41 that holds a workpiece, a cutting device 42 that cuts a workpiece held by the chuck table 41, and a workpiece that is held by the chuck table 41. An imaging means 43 for imaging. The suction cup table 41 is configured to attract and hold the workpiece, and The machining feed means (not shown) moves to the machining feed direction (X-axis direction) indicated by an arrow X in Fig. 7, and the index is indicated by an index (not shown) to the index indicated by the arrow Y. The calibration feed direction (Y-axis direction) moves.

The cutting means 42 includes a spindle housing 421 that is disposed substantially horizontally, a rotating spindle 422 that is rotatably supported by the spindle housing 421, and a cutting blade 423 that is attached to a front end of the rotating spindle 422. The rotating spindle 422 The servo motor (not shown) disposed in the spindle housing 421 is rotated in the direction indicated by the arrow 423a. The cutter 423 is a disk-shaped base 424 formed of a metal material such as aluminum, and an annular blade 425 attached to the outer peripheral portion of the side surface of the base 424. The annular blade 425 is formed by an electroforming knife in which diamond abrasive grains having a particle diameter of 3 to 4 μm are fixed by plating on the outer peripheral portion of the side surface of the base 424 by nickel plating. In the illustrated embodiment, the thickness is 30 μm. The outer diameter is 50 mm.

The imaging means 43 includes an illumination means that is attached to the distal end portion of the spindle housing 421, illuminates the workpiece, an optical system that captures a region illuminated by the illumination means, and an image captured by the optical system. The image pickup device (CCD) or the like transmits an image signal of the image to a control means (not shown).

In the division process using the above-described cutting device 4, as shown in Fig. 7, the dicing tape T side of the semiconductor wafer 2 on which the ridge forming process has been performed is bonded to the chuck table 41. Then, by operating the suction means (not shown), the semiconductor wafer 2 is sucked and held on the chuck table 41 via the dicing tape T (wafer holding process). Therefore, the suction table The semiconductor wafer 2 held by 41 is the upper side of the two ridges 24, 24 formed along the predetermined dividing line 211. In addition, in FIG. 7, the frame F in which the ring shape of the dicing tape T is attached is abbreviate|omitted, and the frame|frame F of the ring-shaped frame F is hold|maintained by the appropriate frame holding means arrange|positioned by the suction-plates 41. In this manner, the chuck table 41 that sucks and holds the semiconductor wafer 2 is positioned directly below the imaging device 43 by a processing feed means (not shown).

When the chuck table 41 is located immediately below the image pickup unit 43, the image pickup means 43 and a control means (not shown) perform a calibration operation for detecting the area of the semiconductor wafer 2 to be cut. In the calibration process, the imaging means 43 performs imaging by imaging the two ridges 24, 24 formed along the predetermined dividing line 211 of the semiconductor wafer 2 by the ridge forming process. In other words, the imaging means 43 and the control means (not shown) are suitable for processing whether or not the two ridges 24, 24 formed along the predetermined dividing line 211 formed in the predetermined direction of the semiconductor wafer 2 are in the processing feed direction ( X-axis direction) Parallel calibration (calibration engineering). If the two ridges 24, 24 formed along the predetermined dividing line 211 formed in the predetermined direction of the semiconductor wafer 2 are not parallel to the machining feed direction (X-axis direction), the suction table 41 is rotated, and both The strip ridges 24 and 24 are adjusted so as to be parallel to the machining feed direction (X-axis direction). Further, the alignment of the cutting regions cut by the cutting blade 423 is similarly performed for the two ridges 24 and 24 formed on the semiconductor wafer 2 in the direction orthogonal to the predetermined direction.

As described above, detecting the two ridges 24, 24 formed along the predetermined dividing line 211 of the semiconductor wafer 2 held on the chuck table 41, and performing calibration of the cutting region, the semiconductor wafer will be held. The chuck table 41 of 2 moves to the cutting start position of the cutting area. At this time, as shown in FIG. 8(a), the semiconductor wafer 2 is one end of the intermediate portion of the two ridges 24, 24 formed along the predetermined dividing line 211 to be cut (the left end in FIG. 8(a)) The positioning is performed in a manner that is more quantitative than the right side of the cutting blade 423 to the right side.

When the semiconductor wafer 2 held by the chuck table 41 of the cutting device 4 is positioned at the cutting start position of the cutting region, the cutting blade 423 is placed at the standby position indicated by the dotted line in FIG. 8(a). As shown by the arrow Z1, the cut is sent to the lower side, as shown by the solid line in Fig. 8(a), and positioned at the predetermined cutting feed position. As shown in FIGS. 8(a) and 8(c), the cutting feed position is set such that the lower end of the cutting blade 423 reaches the position of the dicing tape T adhered to the back surface of the semiconductor wafer 2.

Next, the cutter 423 is rotated at a predetermined rotation speed in the direction indicated by an arrow 423a in Fig. 8(a), and the chuck table 41 is moved at a predetermined cutting feed speed in a direction indicated by an arrow X1 in Fig. 8(a). Then, the suction cup table 8 is as shown in Fig. 8(b), and the other end of the intermediate portion of the two ribs 24, 24 (the right end in Fig. 8(b)) is located on the left side of the cutting blade 423. At the position, the movement of the suction table 41 is stopped. Thus, by performing the cutting feed to the chuck table 41, as shown in FIG. 8(d), the substrate 20 of the semiconductor wafer 2 is formed to reach the region where the two ridges 24, 24 formed on the predetermined dividing line 211 are held. The cutting groove 25 on the back side is cut (cutting work).

Next, the cutting blade 423 is raised as indicated by an arrow Z2 in FIG. 8(b), and is positioned at a standby position indicated by a dotted line, so that the chuck table 41 is moved toward Moving in the direction indicated by the arrow X2 in Fig. 8(b), it returns to the position shown in Fig. 8(a). Then, the chuck table 41 is subjected to exponentially calibrating in a direction perpendicular to the plane of the paper (exponentially calibrated feed direction) by an amount corresponding to the interval of the predetermined dividing line 211, and then formed along a predetermined dividing line 211 to be cut. The intermediate portion of the two ribs 24, 24 is located at a position corresponding to the cutting blade 423. In this manner, when the intermediate portion of the two ridges 24, 24 formed along the next predetermined dividing line 211 is located at a position corresponding to the cutting blade 423, the above-described cutting process is performed.

Furthermore, the above cutting process is performed, for example, the following processing conditions.

Cutter: outer diameter 50mm, thickness 30μm

Cutting speed of the cutter: 20000rpm

Cutting feed rate: 50mm / sec

The above-described cutting process is performed on the intermediate portion of the two ridges 24, 24 formed along all of the predetermined dividing lines 211 formed on the semiconductor wafer 2. As a result, the substrate 20 of the semiconductor wafer 2 is cut along a predetermined dividing line 211 forming the two ridges 24, 24, and is divided into individual devices 212 (divided). As described above, when the division process is performed, by forming the ridge forming process, two ridges 24 and 24 are formed along the predetermined dividing line 211 on the functional layer 21 constituting the semiconductor wafer 2, so that two The ridges 24 and 24 are suppressed such that the destructive force by the cutting blade 423 does not reach the side of the device 212, and the functional layer 21 of the laminated structure device does not peel off, and the quality of the device is not deteriorated.

Here, the function of constituting the semiconductor wafer 2 is suppressed. In the layer 21, an experimental example of the effect of peeling off the functional layer 21 caused by the cutting by the cutting blade 423 among the two ridges 24 and 24 formed by the predetermined dividing line 211 will be described.

[Experimental example] [Experimental example: 1]

The wavelength of the laser beam, the repetition frequency, the spot diameter, and the processing feed speed of the processing conditions of the ridge forming process are fixed as described above, and the average output is changed by 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 W form two ridges 24, 24 formed along a predetermined dividing line 211.

In the average output of 0.1 W and 0.2 W, no swelling of the functional layer was observed, and the effect of peeling off the functional layer 21 due to the cutting of the predetermined dividing line 211 by the cutting blade was not suppressed.

In the average output of 0.3 W, the bulging of the functional layer of about 2 μm was observed, and the effect of suppressing the peeling of the functional layer 21 due to the cutting of the predetermined dividing line 211 by the cutting blade was observed.

In the average output of 0.4 W to 0.7 W, the bulging of the functional layer of about 3 to 5 μm can be observed, and the effect of suppressing the peeling of the functional layer 21 due to the cutting of the predetermined dividing line 211 by the cutting blade can be observed.

In the average output of 0.8 W, the ridge of the functional layer is destroyed, and the pulsed laser light is irradiated onto the upper surface of the substrate to cause slight cracks. However, it can be observed that the suppression is caused by the cutting of the predetermined dividing line 211 caused by the cutting blade. The peeling effect of the functional layer 21 was born, and the bending strength of the device was not lowered.

When the average output exceeds 0.9 W, the ridge of the functional layer is destroyed, and the pulsed laser light is irradiated onto the upper surface of the substrate to cause voids and cracks. However, although the effect of suppressing the peeling of the functional layer 21 which occurs by the cutting of the predetermined dividing line 211 by the cutting blade can be observed, the bending strength of the apparatus is lowered.

Therefore, the energy per pulse of the pulsed laser light is set to 0.3 W/80 MHz to 0.8 W/80 MHz, that is, 4 (3.75) to 10 nJ.

[Experimental example: 2]

The wavelength of the laser beam, the repetition frequency, the spot diameter, and the machining feed speed of the processing conditions of the ridge forming process are fixed as described above, and the machining feed speed changes 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500, 520, 540, 560, 580, 600, 620, 640, 660, 680, 700 mm/sec, forming two formed along the predetermined dividing line 211 Ribs 24, 24.

In the machining feed speed of 260 to 300 mm/sec, the two ribs 24, 24 are partially broken, although the peeling of the functional layer 21 which occurs due to the cutting of the predetermined dividing line 211 by the cutting blade is suppressed. The effect is that the substrate is partially cracked, and the bending strength of the device is lowered.

When the machining feed speed is 320 to 640 mm/sec, the two ridges 24 and 24 which are good are formed, and the peeling of the functional layer 21 which occurs by the cutting of the predetermined dividing line 211 by the cutting blade is suppressed.

When the machining feed speed exceeds 640 mm/sec, the two ribs 24, 24 are partially broken, and the partiality does not suppress the peeling of the functional layer 21 due to the cutting of the predetermined dividing line 211 by the cutting blade. .

According to the above experimental results, in the case of irradiating laser light having a spot diameter of φ10 μm, the processing feed speed is preferably set to 320 to 640 mm/sec, and at this time, the point of the laser light is 4~. 8mm. Therefore, it is preferable that the distance between the point and the point of the laser light of the ridge forming process is set to 4 to 8 nm.

Next, a second embodiment of dividing the semiconductor wafer 2 along the region sandwiched by the two ridges 24, 24 will be described with reference to FIG. The second embodiment of the division project is carried out using the laser processing apparatus 3 shown in Figs. 3 and 4 described above.

In the state in which the division processing is performed using the laser processing apparatus 3, as shown in Fig. 9(a), the suction stage 31 is moved to the laser beam irradiation means 32 for irradiating the laser beam. The laser illuminating region where the concentrator 324 is located is along one end of the intermediate portion of the two ridges 24, 24 formed on the predetermined predetermined dividing line 211 of the semiconductor wafer 2 (Fig. 9(a) The left end is positioned in a manner directly below the concentrator 324. Next, while irradiating the pulsed laser beam having a wavelength that is absorptive to the substrate 20 constituting the semiconductor wafer 2 from the concentrator 324 of the laser beam irradiation means 32, the chuck table 31 is turned to the arrow X1 in Fig. 9(a). The direction shown moves at the machining feed rate. Then, as shown in FIG. 9(b), the other end of the intermediate portion of the two ridges 24, 24 formed along the predetermined dividing line 211 (the right end in FIG. 9(b)) reaches the positive of the concentrator 324. In the lower position, the irradiation of the pulsed laser light is stopped, and the movement of the chuck table 61 is stopped.

By performing the laser processing described above, the substrate 20 constituting the semiconductor wafer 2 is as shown in FIG. 9(c), according to the two ridges 24, 24 formed along the predetermined dividing line 211. The laser processing groove 26 formed in the intermediate portion is cut (laser processing groove forming process).

Further, the above-described laser processing groove forming process is performed under the following processing conditions.

Laser light wavelength: 355nm

Repeat frequency: 50MHz

Average output: 3W

Converging point diameter: φ10μm

Processing feed rate: 100mm / sec

The above-described laser processing trench formation process is performed by the intermediate portion of the two ridges 24, 24 formed along all the predetermined dividing lines 211 formed on the semiconductor wafer 2, and the semiconductor wafer 2 is edged. The predetermined dividing line 211 is cut and divided into individual devices 212 (divided projects). As described above, when the division process is performed, by forming the ridge forming process, two ridges 24 and 24 are formed along the predetermined dividing line 211 on the functional layer 21 constituting the semiconductor wafer 2, so that two The ridges 24 and 24 are suppressed such that the destructive force by the laser light does not reach the side of the device 212, and the functional layer 21 of the laminated device does not peel off, and the quality of the device is not lowered.

2‧‧‧Semiconductor wafer

4‧‧‧Cutting device

20‧‧‧Substrate

21‧‧‧ functional layer

24‧‧ ‧ ribs

33‧‧‧Photography

41‧‧‧Sucker table

42‧‧‧ Cutting means

43‧‧‧Photography

211‧‧‧Predetermined dividing line

212‧‧‧ device

421‧‧‧ spindle housing

422‧‧‧Rotating spindle

423‧‧‧Cutter

423a‧‧ arrow

424‧‧‧Abutment

425‧‧‧blade

T‧‧‧ cutting tape

Claims (6)

A method for processing a wafer is a method for processing a wafer of a device by forming a plurality of regions defined by a plurality of predetermined dividing lines stacked on a functional layer of a surface of a substrate in a lattice pattern, and is characterized by comprising: The rib forming process is performed along a predetermined dividing line formed on the wafer, and the predetermined interval is arranged to illuminate the laser beam to bulge the functional layer along the predetermined dividing line, thereby forming two ridges; and dividing the project The wafer on which the rib is formed is divided by the area held by the two ribs. The method of processing a wafer according to claim 1, wherein in the ridge forming process, an output of the laser beam is set to an output in which only the functional layer is expanded. The method for processing a wafer according to the second aspect of the invention, wherein the ridges form an output of a laser beam, and the energy per pulse of the laser beam is set to 4 to 10 nj. The method for processing a wafer according to the third aspect of the invention, wherein the distance between the point and the point of the laser beam of the ridge forming process is set to 4 to 8 nm. The method for processing a wafer as described in claim 1 or 2, wherein the dividing project is such that the cutting blade is held by two ribs The region cuts the wafer along a predetermined dividing line. The method for processing a wafer according to the first or second aspect of the patent application, wherein the dividing project is to irradiate a laser beam to a region held by two ridges along a predetermined dividing line. Cut the wafer.