TWI687984B - Wafer processing method - Google Patents

Abstract

Provides that the functional layers of the wafers of the device forming the device divided by the plurality of predetermined dividing lines formed on the surface of the functional layer laminated on the surface of the substrate in a grid-like manner are not peeled, and the substrate does not cause pores or cracks, etc., A method of processing wafers divided along a predetermined dividing line.

A wafer processing method is a wafer processing method for forming a device by forming a grid in a plurality of regions divided by a plurality of predetermined dividing lines of a functional layer stacked on a substrate surface, which includes: A predetermined dividing line formed on the wafer, a predetermined interval is set and laser light is irradiated to swell the functional layer along the predetermined dividing line, thereby forming a convex strip forming process of two convex strips, and along two convex strips The sandwiched area is divided into wafers for the convex strip forming process.

Description

Wafer processing method

The present invention relates to a wafer processing method for dividing a wafer forming a device by a functional layer stacked on a surface of a substrate such as silicon along a predetermined dividing line.

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

Recently, in order to improve the processing capability of semiconductor wafers such as ICs and LSIs, inorganic substrate films such as SiO ₂ , SiOF, BSG (SiOB), and polyimide-based, poly A functional layer of a low-dielectric insulator film (Low-k film) formed of a polymer film such as a paraxylene system, that is, an organic film, is used as a semiconductor wafer in the 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 dicing machine. The cutting device is It includes a chuck table that holds a semiconductor wafer that is a workpiece, cutting means for cutting the semiconductor wafer held by the chuck table, and moving means for relatively moving the chuck table and the cutting means. The cutting means includes a rotating spindle rotating at a high speed and a cutting blade mounted on the spindle. The cutting blade is formed by a disc-shaped abutment and a ring-shaped blade attached to the outer peripheral portion of the side surface of the abutment. The blade is formed by electroplating and fixing diamond abrasive grains having a particle size of about 3 μm, for example.

However, the aforementioned Low-k film is difficult to be cut by a cutter. That is, since the Low-k film is very fragile like mica, if the cutting blade cuts along a predetermined dividing line, the Low-k film will peel off, and this peeling will cause fatal damage to the device until it reaches the circuit.

In order to eliminate the aforementioned problems, Patent Document 1 described later discloses that a laser processing groove is formed along a predetermined dividing line by irradiating laser light of a wavelength having absorption to the functional layer along a predetermined dividing line formed on the semiconductor wafer The functional layer is removed, the cutting blade is positioned in the laser processing groove, and the cutting blade and the semiconductor wafer are relatively moved, thereby cutting the semiconductor wafer along a predetermined dividing line.

[Prior Technical Literature] [Patent Literature]

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

Then, by irradiating waves that are absorbing to the functional layer If a long laser beam is formed along a predetermined dividing line to form a laser processing groove to remove the functional layer, the laser beam from the removed functional layer is irradiated to a semiconductor substrate such as a silicon substrate or a gallium nitride substrate, and the semiconductor substrate may be damaged. Porosity or cracks at the starting point have the problem of reducing the flexural strength of the device.

The present invention is invented in view of the foregoing facts, and its main technical object is to provide a wafer that does not allow a device to form a plurality of regions divided by a plurality of predetermined dividing lines formed in a functional layer laminated on the surface of a substrate in a lattice The functional layer is peeled, and the substrate is not allowed to produce pores or cracks, and the wafer can be divided along a predetermined dividing line.

In order to solve the aforementioned main technical problems, according to the present invention, there is provided a wafer processing method, which is formed by forming a plurality of regions divided by a plurality of predetermined dividing lines formed in a grid on a functional layer laminated on the surface of a substrate The wafer processing method of the device is characterized by including: a protruding strip forming process, which is to set a predetermined interval along the predetermined dividing line formed on the wafer and irradiate the laser light, so that the functional layer is raised along the predetermined dividing line. This forms two convex strips; and the segmentation process is to split the wafer that implements the convex strip formation process along the region held by the two convex strips.

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

The output of the aforementioned laser beam forming the laser beam is the energy per pulse of the laser beam is set to 4-10 nj.

In addition, the distance between the points of the laser beams of the aforementioned convex strip forming process is set to 4 to 8 nm.

In the foregoing segmentation process, the cutting blade is located in the region held by the two convex strips, and the wafer is cut along the predetermined segmentation line.

In addition, the aforementioned segmentation process is to irradiate the region held by the two convex strips with laser light and cut the wafer along a predetermined segmentation line.

The wafer processing method according to the present invention includes arranging predetermined intervals along a predetermined dividing line formed on the wafer and irradiating laser light to swell the functional layer along the predetermined dividing line, thereby forming two convex strips The project of forming the convex strips and the segmentation process of the wafer along the region held by the two convex strips to divide the convex strip forming process, The functional layer constituting the wafer is formed with two convex strips along the predetermined dividing line, so the two convex strips suppress the destructive force caused by the irradiation of the cutter and the laser beam so as not to reach the device side. The stacked functional layers that make up the device will not peel off and will not degrade the quality of the device.

2: Semiconductor wafer

3: Laser processing device

31: Chuck table of laser processing device

32: Laser light irradiation means

324: Concentrator

33: camera means

4: Cutting device

41: Sucker table of cutting device

42: Cutting method

421: Spindle housing

422: Rotating spindle

423: Cutter

423a: arrow

424: Abutment

425: Blade

43: Camera means

F: ring frame

T: cutting tape

[Fig. 1] A perspective view and an enlarged cross-sectional view of a main part of a semiconductor wafer as a wafer processed by the wafer processing method according to the present invention.

[FIG. 2] It is disclosed that the semiconductor wafer shown in FIG. 1 is bonded to and mounted on A perspective view of the state of the ring-shaped frame cutting the surface of the tape.

[Fig. 3] A perspective view of a main part of a laser processing apparatus for implementing a convex strip forming process of a wafer processing method according to the present invention.

[Fig. 4] A block structure diagram of a laser light irradiation means equipped in the laser processing apparatus shown in Fig. 3.

[Fig. 5] An explanatory diagram of a projecting process of forming a convex strip of a wafer processing method according to the present invention.

[Fig. 6] A block structure diagram showing another embodiment of a condenser that constitutes a laser beam irradiation means equipped in the laser processing apparatus shown in Fig. 3.

7 is a perspective view of a main part of a cutting device as a cutting process for performing a wafer processing method according to the present invention as a division process.

[Fig. 8] An explanatory diagram of a cutting process as a division process of a wafer processing method according to the present invention.

[Fig. 9] An explanatory diagram of a laser processing trench formation process as a division process of the wafer processing method according to the present invention.

Hereinafter, an ideal embodiment of the wafer processing method according to the present invention will be described in detail with reference to the attached drawings.

1(a) and (b) of FIG. 1 disclose a perspective view and an enlarged cross-sectional view of a main part of a semiconductor wafer as a wafer. The semiconductor wafer 2 shown in FIGS. In a plurality of regions divided by a plurality of predetermined division lines 211 formed in the functional layer 21 in a lattice shape, devices 212 such as ICs, LSIs, etc. are formed. In addition, in the illustrated embodiment, the insulating film forming the functional layer 21 is composed of an SiO ₂ film, an inorganic film such as SiOF, BSG (SiOB), or a polyimide-based or parylene-based film. The polymer film, that is, a low-dielectric insulator film (Low-k film) made of an organic film, has a thickness of 10 μm. In addition, the width of the predetermined dividing line 211 is set to 50 μm in the illustrated embodiment.

For dividing the above-mentioned semiconductor wafer 2 along a predetermined dividing line 211, first, a dicing tape is adhered to the back of the substrate 20 constituting the semiconductor wafer 2, and the outer peripheral portion of the dicing tape is supported by a ring-shaped frame Of wafer support engineering. That is, as shown in FIG. 2, the back surface 20 b of the substrate 20 constituting the semiconductor wafer 2 is bonded to the surface of the dicing tape T on which the outer peripheral portion is mounted so as to cover the inner opening of the ring-shaped frame F. Therefore, the semiconductor wafer 2 adhered to the surface of the dicing tape T has the surface 21a of the functional layer 21 on the upper side.

If the wafer support process described above is implemented, laser beams are irradiated at predetermined intervals along a predetermined dividing line 211 formed on the semiconductor wafer 2 to swell the functional layer 21 along the predetermined dividing line 211, thereby forming The convex strips of the two convex strips form the project. This ridge formation 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 that holds the workpiece, a laser beam irradiating means 32 that irradiates the laser beam to the workpiece held on the chuck table 31, and An imaging means 33 for imaging the workpiece on the chuck table 31. The chuck table 31 is used to attract and hold the workpiece The method is configured to move to the processing feed direction (X-axis direction) indicated by the arrow X in FIG. 3 by processing feed means not shown, and by indexing feed means not shown, Move to the indexed feed direction (Y-axis direction) indicated by arrow Y in Figure 3.

The laser beam irradiation means 32 includes a cylindrical casing 321 extending substantially horizontally. The laser beam irradiation means 32 will be described with reference to FIG. 4.

The illustrated laser light irradiation means 32 includes a pulsed laser light oscillating means 322 disposed in the housing 321, and adjusts the output of the pulsed laser light LB oscillated by the pulsed laser light oscillating means 322 Output adjustment means 323, the pulsed laser light adjusted by the output adjustment means 323 is irradiated to the condenser 324 of the workpiece W held on the holding surface of the chuck table 31.

The aforementioned pulsed laser light oscillation means 322 is composed of a pulsed laser light oscillator 322a which oscillates the pulsed laser light, and a repetition frequency setting means 322b which sets the repetition frequency of the pulsed laser light oscillated by the pulsed laser light oscillator 322a constitute. In addition, the pulsed laser light oscillator 322a is in the illustrated embodiment, and oscillates the pulsed laser light LB with a wavelength of 355 nm.

The aforementioned output adjustment means 323 adjusts the output of the pulsed laser light oscillated from the pulsed laser light oscillation means 322 to a predetermined output. The pulse laser light oscillator 322a, the repetition frequency setting means 322b, and the output adjustment means 323 of the pulse laser light oscillation means 322 are controlled by control means (not shown).

The condenser 324 includes a direction conversion mirror 324a that oscillates from the pulsed laser light oscillation means 322 and adjusts the output pulsed laser light by the output adjustment means 323 toward the holding surface of the chuck table 31, and The pulsed laser light converted in the direction by the direction conversion mirror 324a is condensed and irradiated to the condensing lens 324b of the workpiece W held by the chuck table 31. As shown in FIG. 3, the condenser 324 configured in this manner is attached to the housing 321.

Returning to FIG. 3 for continuous description, the imaging means 33 is attached to the front end portion of the housing 321 constituting the laser light irradiation means 32. The imaging means 33 is composed of an optical system such as a microscope and an imaging element (CCD), etc., and sends the image signal of the imaging to a control means (not shown).

For the laser processing apparatus 3 described above, the laser beam is irradiated at a predetermined interval along a predetermined dividing line 211 formed on the semiconductor wafer 2, and the functional layer 21 is raised along the predetermined dividing line 211, thereby forming two The convex strip forming process of the convex strip 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 a 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 surface 21a of the functional layer 21 on the upper side. In addition, in FIG. 3, the ring-shaped frame F to which the dicing tape T is attached is omitted and disclosed, but the ring-shaped frame F is held by a suitable frame holding means disposed on the chuck table 31. As a result, attract and maintain semiconductor wafers The chuck table 31 of 2 is located directly below the imaging means 33 by processing and feeding means (not shown).

When the chuck table 31 is located directly under the imaging means 33, the imaging means 33 and the control means (not shown) are used to perform the calibration operation of the processing area where the semiconductor wafer 2 should be laser-processed. That is, the imaging means 33 and the control means (not shown) execute a predetermined dividing line 211 for forming a predetermined direction formed on the semiconductor wafer 2 and laser light irradiating the laser beam along the predetermined dividing line 211 Image processing such as alignment pattern matching of the condenser 324 of the irradiation means 32 appropriately performs laser beam irradiation position calibration (calibration process). In addition, the predetermined division line 211 formed on the semiconductor wafer 2 in a direction orthogonal to the above-described predetermined direction is similarly adapted to the alignment of the laser light irradiation position.

When the above calibration process is performed, as shown in FIG. 3, the chuck table 31 is moved to the laser light irradiation area where the condenser 324 of the laser light irradiation means 32 that irradiates the laser light is located, as shown in FIG. 5( a) As shown in the figure, one end of the predetermined predetermined dividing line 211 formed on the semiconductor wafer 2 (the left end in FIG. 5(a)) is positioned so as to be directly under the condenser 324. At this time, positioning is performed so as to be located directly below the condenser 324 from the center in the width direction of the predetermined dividing line 211 to one side, for example, 20 μm. Then, the condensing point P of the pulsed laser light LB irradiated from the condenser 324 is positioned near the surface (upper surface) of the functional layer 21 of the predetermined dividing line 211. Next, while irradiating the pulse laser light of the output set to expand only the functional layer 21 from the condenser 324 of the laser light irradiation means 32, the chuck table 31 is directed toward the arrow X1 in FIG. 5(a). direction Move at machining feed rate. 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 condenser 324, the irradiation of the pulsed laser light is stopped, and the The movement of the chuck table 31.

Next, the chuck table 31 is moved in a direction perpendicular to the paper surface (index index feed direction), for example, 40 μm. As a result, it is positioned so as to be positioned directly below the condenser 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 irradiating the pulsed laser light from the condenser 324 of the laser light irradiation means 32, the chuck table 31 is moved in the direction indicated by the arrow X2 at a predetermined processing feed rate to reach At 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-mentioned convex strip formation process, as shown in FIG. 5( d ), two convex strips 24 and 24 protruding along the predetermined dividing line 211 are formed on the functional layer 21 of the semiconductor wafer 2. Then, the above-mentioned protrusion forming process is carried out along all the predetermined dividing lines 211 formed on the semiconductor wafer 2.

In addition, the aforementioned ridge forming process is performed under the following processing conditions, for example.

Laser light wavelength: 355nm

Repetition frequency: 80MHz

Average output: 0.5W

Condensing spot diameter: φ10μm

Processing feed speed: 450mm/sec

Next, other embodiments of the condenser 324 constituting the laser beam irradiation means 32 of the laser processing apparatus 3 that performs the aforementioned rib forming process will be described with reference to FIG. 6.

The condenser 324 shown in FIG. 6 is disposed between the direction conversion mirror 324a and the condenser lens 324b, and is provided with Wollaston that diverges the pulsed laser light converted by the direction conversion mirror 324a in the Y-axis direction The disagreement means of 黜鏡 et al. 324c. The condenser 324 configured in this way irradiates the pulsed laser beams LB1 and LB2 diverged by the diverging means 324c at a predetermined interval in the Y-axis direction. Therefore, by using the concentrator 324 shown in FIG. 6, two convex strips that are raised along the predetermined dividing line can be simultaneously formed. Furthermore, when the condenser 324 shown in FIG. 6 is used, the output of the pulsed laser beams LB1 and LB2 diverged by the branching means 324c becomes the pulsed laser beam LB oscillated from the pulsed laser light oscillation means 322 1/2 of the output, so the average output of the pulsed laser light LB oscillated from the pulsed laser light oscillating means 322 in the aforementioned ridge formation process is set to 1.0W.

When the above-mentioned convex stripe forming process has been implemented, the semiconductor wafer 2 is split and split along the region held by the two convex strips 24 and 24. The first embodiment of this division process 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 the workpiece, a cutting device 42 that cuts the workpiece held on the chuck table 41, and the workpiece held by the chuck table 41 Imagining means 43 for performing imaging. The chuck table 41 is constructed to attract and hold the workpiece, by Move to the machining feed direction (X-axis direction) indicated by the arrow X in FIG. 7 by the machining feed means not shown, and calibrate the feed means by the index not shown to the index indicated by the arrow Y Move in the calibration feed direction (Y-axis direction).

The aforementioned cutting means 42 includes a spindle housing 421 arranged substantially horizontally, a rotary spindle 422 rotatably supported by the spindle housing 421, and a cutting blade 423 attached to the front end of the rotary spindle 422, and the rotary spindle 422 A servo motor (not shown) disposed in the spindle housing 421 rotates in the direction shown by arrow 423a. The cutting blade 423 is a disc-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 ring-shaped blade 425 is formed by an electroforming blade that fixes diamond abrasive grains with a particle diameter of 3 to 4 μm to the outer peripheral portion of the side surface of the base 424 by nickel plating. In the illustrated embodiment, the thickness is 30 μm and The outer diameter is 50mm.

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

For performing the dividing process using the above-mentioned cutting device 4, as shown in FIG. 7, the dicing tape T side of the semiconductor wafer 2 that has undergone the aforementioned protrusion forming process is bonded to the chuck table 41. Then, by operating a 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). So, the sucker table The semiconductor wafer 2 held by 41 is formed with two ridges 24, 24 along the predetermined dividing line 211 on the upper side. In addition, in FIG. 7, the ring-shaped frame F to which the dicing tape T is attached is omitted and disclosed. However, the ring-shaped frame F is held by suitable frame holding means arranged on the chuck table 41. In this way, the chuck table 41 that attracts and holds the semiconductor wafer 2 is located directly below the imaging means 43 by processing and feeding means (not shown).

When the chuck table 41 is located directly under the imaging means 43, the imaging means 43 and the control means (not shown) are used to perform the calibration operation of the area where the semiconductor wafer 2 should be cut. In this calibration process, the imaging means 43 executes imaging of the two ridges 24 and 24 formed along the predetermined dividing line 211 of the semiconductor wafer 2 by the aforementioned ridge formation process. That is, whether the imaging means 43 and the control means (not shown) are in accordance with whether the two ridges 24, 24 formed along the predetermined dividing line 211 formed in the predetermined direction of the semiconductor wafer 2 and the processing feed direction ( X axis direction) parallel calibration (calibration process). 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 processing feed direction (X-axis direction), the chuck table 41 is rotated, and the two The ridges 24 and 24 are adjusted so as to be parallel to the processing feed direction (X-axis direction). In addition, the two ridges 24 and 24 formed on the semiconductor wafer 2 in a direction orthogonal to the above-mentioned predetermined direction are similarly appropriately adjusted for the cutting area cut by the cutting blade 423.

As described above, if the two ridges 24, 24 formed along the predetermined dividing line 211 of the semiconductor wafer 2 held on the chuck table 41 are detected and the alignment of the cutting area is performed, the semiconductor wafer will be held The chuck table 41 of 2 moves to the cutting start position in the cutting area. At this time, as shown in FIG. 8(a), the semiconductor wafer 2 is formed with one end of the middle portion of the two ridges 24, 24 formed along the predetermined dividing line 211 to be cut (left end in FIG. 8(a)) ) It is positioned so that it is offset to the right by a certain amount from directly below the cutting blade 423.

In this way, when the semiconductor wafer 2 held on the chuck table 41 of the cutting device 4 is positioned at the cutting start position of the cutting processing area, the cutting blade 423 is moved from the standby position shown by the dotted line in FIG. 8(a) As shown by the arrow Z1, the cutting feed is sent downward, as shown by the solid line in FIG. 8(a), and it is 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 dicing tape T adhered to the back surface of the semiconductor wafer 2.

Next, the cutting blade 423 is rotated at a predetermined rotation speed in the direction shown by arrow 423a in FIG. 8(a), and the chuck table 41 is moved at a predetermined cutting feed speed in the direction shown by arrow X1 in FIG. 8(a). Then, as shown in FIG. 8(b), the other end of the middle portion of the two ridges 24, 24 (the right end in FIG. 8(b)) reaches the left side more directly below the cutting blade 423 as shown in FIG. 8(b). Position, the movement of the chuck table 41 is stopped. In this way, by cutting and feeding the chuck table 41, as shown in FIG. 8(d), the substrate 20 of the semiconductor wafer 2 is formed to reach the region held by the two ridges 24, 24 formed on the predetermined dividing line 211 The cutting groove 25 on the back side is cut (cutting work).

Next, the cutting blade 423 is raised as indicated by the arrow Z2 in FIG. 8(b), positioned at the standby position indicated by the dotted line, and the chuck table 41 is moved toward Move in the direction indicated by arrow X2 in Fig. 8(b) and return to the position shown in Fig. 8(a). Then, the chuck table 41 is indexed and fed in a direction perpendicular to the paper surface (index calibration feed direction) by an amount corresponding to the interval of the predetermined dividing line 211, and then formed along the predetermined dividing line 211 to be cut The middle portion of the two ridges 24, 24 is located at a position corresponding to the cutting blade 423. In this way, when the middle 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-mentioned cutting process is performed.

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

Cutter: outer diameter 50mm, thickness 30μm

Cutter rotation speed: 20000rpm

Cutting feed rate: 50mm/sec

The above-mentioned cutting process is carried out at the middle of the two ridges 24, 24 formed along all 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 the predetermined dividing line 211 where the two ridges 24, 24 are formed, and is divided into individual devices 212 (dividing process). In this way, when the dividing process is carried out, two convex stripes 24 and 24 are formed along the predetermined dividing line 211 on the functional layer 21 constituting the semiconductor wafer 2 by performing the aforementioned convex strip forming process. The protrusions 24 and 24 are suppressed in such a way that the destructive force caused by the cutting blade 423 does not reach the device 212 side, the functional layer 21 constituting the device is not peeled off, and the quality of the device is not degraded.

Here, to suppress the function of constituting the semiconductor wafer 2 The layer 21 is an experimental example of the effect of peeling of the functional layer 21 due to cutting by the cutting blade 423 among the two ridges 24 and 24 formed along the predetermined dividing line 211.

[Experiment example] [Experiment example: 1]

The laser beam wavelength, repetition frequency, condensing spot diameter, and processing feed speed of the processing conditions of the aforementioned convex strip 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, 1.0W, forming two ridges 24, 24 formed along the predetermined dividing line 211.

At an average output of 0.1 W and 0.2 W, no swelling of the functional layer was observed, and there was no effect of suppressing the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 by the cutter.

At an average output of 0.3 W, the bulge of the functional layer of about 2 μm was observed, which had the effect of suppressing the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 by the cutter.

With an average output of 0.4 W to 0.7 W, the bulge of the functional layer of about 3 to 5 μm is observed, which has the effect of suppressing the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 caused by the cutter.

At an average output of 0.8W, the uplift of the functional layer was destroyed, and pulsed laser light irradiated the substrate to cause a slight crack. However, it can be observed that the occurrence of cutting due to cutting along the predetermined dividing line 211 caused by the cutter is suppressed The peeling effect of the functional layer 21 is not reduced, and the bending strength of the device is not reduced.

If the average output exceeds 0.9W, the uplift of the functional layer will be destroyed, and the pulsed laser light will irradiate the substrate, causing pores and cracks. However, although the effect of suppressing the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 due to the cutting blade can be observed, the bending strength of the device is reduced.

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

[Experiment example: 2]

The laser beam wavelength, repetition frequency, condensing spot diameter, and processing feed speed of the processing conditions of the aforementioned convex strip forming process are fixed as described above, and the processing feed speed is changed by 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 Convex strips 24, 24.

At a processing feed rate of 260 to 300 mm/sec, the two ridges 24, 24 are partially broken, although the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 caused by the cutter is suppressed Effect, but the substrate partially cracks, and the bending strength of the device is reduced.

At a processing feed rate of 320 to 640 mm/sec, two good ridges 24 and 24 are formed, which has the effect of suppressing the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 caused by the cutter.

When the processing feed rate exceeds 640 mm/sec, the two convex strips 24 and 24 are partially broken, and there is no effect of suppressing the peeling of the functional layer 21 due to cutting along the predetermined dividing line 211 caused by the cutter .

According to the foregoing experimental results, in the case of irradiating laser light with a condensing spot diameter of φ10 μm, the processing feed rate is preferably 320 to 640 mm/sec. At this time, the distance between the point of the laser light and the point is 4 to 8mm. Therefore, it is better to set the distance between the dots and the dots of the laser beam of the aforementioned convex strip forming project to 4-8 nm.

Next, the second embodiment of the division process of dividing the semiconductor wafer 2 along the region sandwiched by the two ridges 24 and 24 will be described with reference to FIG. 9. The second embodiment of this division process is implemented using the laser processing apparatus 3 shown in FIGS. 3 and 4 described above.

For performing the division process using the laser processing device 3, from the state where the aforementioned ridge forming process has been performed, as shown in FIG. 9(a), the chuck table 31 is moved to the laser light irradiation means 32 which irradiates the laser light The laser beam irradiation area where the condenser 324 is located is along one end of the middle portion of the two ridges 24, 24 formed on the predetermined predetermined dividing line 211 formed on the semiconductor wafer 2 (in FIG. 9(a) (Left end) is positioned so as to be directly below the condenser 324. Next, while irradiating pulsed laser light of a wavelength having absorption to the substrate 20 constituting the semiconductor wafer 2 from the condenser 324 of the laser light irradiation means 32, the chuck table 31 is directed to 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 (the right end in FIG. 9(b)) of the middle portion of the two ridges 24, 24 formed along the predetermined dividing line 211 reaches the front of the condenser 324 In the lower position, the irradiation of pulsed laser light is stopped, and the movement of the chuck table 31 is stopped.

By performing the above-mentioned laser processing process, 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 middle portion is cut (laser processing groove forming process).

In addition, the laser processing trench formation process is performed under the following processing conditions, for example.

Laser light wavelength: 355nm

Repetition frequency: 50MHz

Average output: 3W

Condensing spot diameter: φ10μm

Processing feed speed: 100mm/sec

By performing the above-mentioned laser processing trench formation process along the middle of the two ridges 24, 24 formed along all the predetermined dividing lines 211 formed on the semiconductor wafer 2, the semiconductor wafer 2 is along The predetermined dividing line 211 is cut and divided into individual devices 212 (dividing process). In this way, when the dividing process is carried out, two convex stripes 24 and 24 are formed along the predetermined dividing line 211 on the functional layer 21 constituting the semiconductor wafer 2 by performing the aforementioned convex strip forming process. The ridges 24 and 24 are suppressed in such a way that the destructive force caused by the laser light does not reach the device 212 side, and the functional layer 21 constituting the device is not peeled off, and the quality of the device is not degraded.

2‧‧‧Semiconductor wafer

4‧‧‧Cutting device

20‧‧‧ substrate

21‧‧‧Functional layer

24‧‧‧Convex strip

33‧‧‧Camera means

41‧‧‧Sucker table

42‧‧‧Cutting means

43‧‧‧Camera

211‧‧‧Scheduled dividing line

212‧‧‧ installation

421‧‧‧spindle housing

422‧‧‧rotating spindle

423‧‧‧Cutter

423a‧‧‧arrow

424‧‧‧Abutment

425‧‧‧Blade

T‧‧‧cutting tape

Claims (5)

A wafer processing method is a wafer processing method for forming a device by forming a plurality of regions divided by a plurality of predetermined dividing lines of a low-k film laminated on the surface of a substrate in a lattice shape, characterized by Including: the protruding strip formation process, which is to set a predetermined interval along the predetermined dividing line formed on the wafer and irradiate the laser light to swell the Low-k film along the predetermined dividing line, thereby forming two convex strips; and dividing The project is to divide the wafer that implements the convex strip forming process along the region held by the two convex strips; in the convex strip forming process, the focus point of the laser light is positioned at the low of the predetermined split line -Near the surface of the k-film, the output of laser light is set to an output that expands the Low-k film only. The wafer processing method as described in item 1 of the patent application scope, in which the output of the laser beam of the convex strip forming process is that the energy per pulse of the laser beam is set to 4 to 10 nj. The wafer processing method as described in item 2 of the patent application scope, wherein the distance between the points of the laser beams of the convex strip forming process is set to 4 to 8 nm. The wafer processing method as described in any one of the first to third patent application scopes, wherein the division process is such that the cutting blade is located in the region held by the two convex strips along the predetermined division Wire to cut the wafer. The wafer processing method as described in any one of claims 1 to 3, wherein the segmentation process is to irradiate laser light to the area held by the two convex strips, along The dividing line is predetermined to cut the wafer.

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