JP7674012B1 - Laser dicing device and method for manufacturing substrate - Google Patents

Abstract

The present disclosure has an object to provide a laser dicing device that can easily obtain a substrate having a desired groove.
[Solution] A laser dicing apparatus according to one aspect of the present disclosure is a laser dicing apparatus that forms grooves for singulating a substrate by irradiating laser light, and includes a stage on which the substrate is placed and a laser light irradiation unit that irradiates laser light onto the substrate placed on the stage, the laser light irradiation unit including a pulsed fiber laser.
[Selected Figure] Figure 1

Description

This disclosure relates to a laser dicing device and a method for manufacturing a substrate.

Semiconductor devices are attached to semiconductor device chips and installed in various products. A technology is known for obtaining semiconductor device chips by dicing semiconductor substrates such as wafers (JP Patent Publication No. 2023-091141).

JP 2023-091141 A

In Patent Document 1, grooves are formed along the planned dividing lines in the wafer by cutting with a blade or ablation processing by irradiating laser light, and the wafer is divided to obtain chips for semiconductor devices. In cutting the wafer with a blade, it is necessary to clean the chips generated by cutting and replace worn blades, so there is a risk that chips for semiconductor devices cannot be produced efficiently. In ablation processing of the wafer by irradiating laser light, it is not necessary to clean the wafer or replace the blade, but if the processing is performed at high speed, there is a risk that a sufficiently deep groove cannot be formed, and burrs may be generated in the formed groove due to laser energy or blackening may occur due to heat. If the output of the laser light is reduced to suppress the occurrence of burrs or blackening, slippage (partial failure to form grooves) may occur, and if the processing speed (speed at which the grooves are formed) is reduced to suppress slippage, there is a risk that the efficiency of forming the grooves may decrease.

In view of the above circumstances, the present disclosure aims to provide a laser dicing device that can easily produce a substrate with the desired grooves.

The laser dicing device according to one aspect of the present disclosure, which has been made to solve the above problems, is a laser dicing device that forms grooves for singulating a substrate by irradiating the substrate with laser light, and includes a stage on which the substrate is placed, and a laser light irradiation unit that irradiates the substrate placed on the stage with laser light, and the laser light irradiation unit includes a pulsed fiber laser.

The laser dicing device according to one aspect of the present disclosure can easily produce a substrate with the desired grooves.

FIG. 1 is a schematic plan view showing a laser dicing apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic front view of the laser dicing apparatus of FIG. FIG. 3 is a schematic plan view showing a state in which the laser dicing apparatus of FIG. 1 forms grooves in a substrate. FIG. 4 is a schematic front view of the laser dicing apparatus of FIG.

[Description of the embodiments of the present disclosure]
First, the embodiments of the present disclosure will be listed and described.

(1) A laser dicing device according to one aspect of the present disclosure is a laser dicing device that forms grooves for singulating a substrate by irradiating the substrate with laser light, and includes a stage for placing the substrate thereon and a laser light irradiating unit that irradiates the substrate placed on the stage with laser light, the laser light irradiating unit including a pulsed fiber laser.

In this laser dicing device, the laser light irradiation unit that irradiates the laser light includes a pulsed fiber laser, and the laser light emitted by this pulsed fiber laser is irradiated onto a substrate placed on a stage to form grooves for singulation. Since the pulsed fiber laser has high energy conversion efficiency, it can irradiate laser light with a high peak intensity, and can easily form sufficiently deep grooves in the substrate. In addition, since the laser light with a high peak intensity is irradiated in a short time, the fracture of the substrate surface to form the grooves is performed in a short time, and burrs in the grooves can be suppressed, and since heating of the substrate surface is suppressed, blackening of the formed grooves can also be suppressed.

(2) In the above (1), the average output of the laser light emitted by the pulsed fiber laser may be 70 W or more. By having the average output of the laser light be 70 W or more, the processing speed can be improved, and the efficiency of forming grooves of sufficient depth can be improved.

(3) In the above (1) or (2), the pulse width of the laser light emitted by the pulsed fiber laser may be 2.0 μsec or less. By setting the pulse width of the laser light to 2.0 μsec or less, the reliability of forming a groove of sufficient depth can be further improved.

(4) A method for manufacturing a substrate according to one aspect of the present disclosure is a method for manufacturing a substrate having grooves for singulation, comprising the steps of placing the substrate on a stage and irradiating the substrate, which is being moved by the stage, with laser light to form grooves having a depth of 30 μm or more, the laser light being emitted from a pulsed fiber laser.

Since the grooves in the substrate are formed by the laser light emitted by the pulsed fiber laser, grooves with a depth of 30 μm or more can be easily and reliably formed, making it easy to obtain a substrate having grooves deep enough for individualization, and easily suppressing burrs and blackening on the surface (inner surface) of the grooves.

(5) A laser dicing device according to one aspect of the present disclosure is a laser dicing device that forms grooves in a substrate for singulating by irradiating the substrate with laser light, and includes a substrate accommodation unit that accommodates multiple substrates, a stage that moves in one direction within a plane parallel to the surface of the substrate placed thereon and in a direction perpendicular to the one direction, a transport unit that transports the substrate from the substrate accommodation unit to the stage, an imaging unit that photographs the substrate transported by the transport unit, a laser light irradiation unit that irradiates the substrate placed on the stage with laser light, and a control unit that controls the movement of the stage, and the control unit detects the orientation of the substrate within the plane from an image captured by the imaging unit and controls the movement of the stage based on the detected orientation.

In this laser dicing device, a control unit that controls the movement of the stage detects the orientation of the substrate in a plane parallel to the surface of the substrate from an image captured by the imaging unit, and controls the movement of the stage based on the detected orientation. Since the stage moves along the orientation of the substrate without correcting it, this laser dicing device can efficiently form grooves in the desired orientation on the substrate.

[Details of the embodiment of the invention]
Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the drawings are illustrative of the embodiments, and the shape, size, scale, arrangement, etc. of each component (member) may differ from the actual ones.

<Laser dicing device>
As shown in Fig. 1 to Fig. 4, the laser dicing device includes a stage 10 on which a substrate is placed, and a laser light irradiation unit 20 that irradiates the substrate placed on the stage 10 with laser light L. The laser dicing device also includes a substrate accommodation unit that accommodates a plurality of substrates P, a transport unit 40 that transports the substrate P from the substrate accommodation unit to the stage 10, an imaging unit that photographs the substrate P transported by the transport unit 40, and a control unit (not shown) that controls the movement of the stage 10. The stage 10 moves in one direction (X direction) and in a direction perpendicular to the one direction (Y direction) within a plane parallel to the surface (upper and lower surfaces) of the substrate P placed thereon. The stage 10, the laser light irradiation unit 20, the substrate accommodation unit, the transport unit 40, the imaging unit, and the control unit are housed in a housing (not shown).

<Substrate>
On the top surface of the substrate P (the surface opposite to the surface placed on the stage 10), grooves P1 for singulation (division into a plurality of small pieces) are formed to a depth of 30 μm or more by the laser dicing device. This substrate P can be obtained by a manufacturing method including a step of placing the substrate P on the stage 10 and a step of irradiating the substrate P moving by the stage 10 with laser light L to form grooves P1 to a depth of 30 μm or more. The laser light L is emitted from a pulse fiber laser. A plurality of grooves P1 perpendicular to each other are formed on the top surface of the substrate P.

The substrate P is not particularly limited as long as it is a substrate that is singulated by the formed grooves, and may be, for example, a semiconductor substrate. The shape of the substrate P may be substantially circular, substantially rectangular, substantially elliptical, or substantially polygonal. In Figs. 1 to 4, a rectangular substrate P for semiconductor use is shown. At least a part of the end face (split surface) of the singulated substrate P is used as an electrode. Specifically, the substrate P is singulated by coating an electrode material (not shown) on the formed grooves P1, or by forming the grooves P1 and singulating the substrate P, and then coating an electrode material to form an electrode on a part or all of the end face.

The material of the substrate P is not particularly limited as long as it is capable of forming the grooves P1 by irradiation with the laser light L, and may be, for example, alumina (Al ₂ O ₃ ) ceramics, aluminum nitride (AlN) ceramics, etc. The size (external dimensions) of the substrate P is not particularly limited as long as it is a size that can be processed by the laser dicing device.

[Substrate accommodating section]
The substrate accommodating section accommodates a plurality of substrates P. The laser dicing apparatus of this embodiment has a first substrate accommodating section 31 that accommodates the substrate P before the grooves P1 are formed, and a second substrate accommodating section 32 that accommodates the substrate P after the grooves P1 are formed.

The manner in which the substrate accommodating sections 31, 32 accommodate multiple substrates P is not particularly limited, and for example, multiple substrates P may be stacked in the thickness direction. The substrate accommodating sections 31, 32 may be configured to be detachable from the laser dicing device, or may be fixed so that they cannot be detached. The laser dicing device may include multiple first substrate accommodating sections 31 and multiple second substrate accommodating sections 32.

[Transportation section]
The transport unit 40 takes out one of the multiple substrates P accommodated in the first substrate accommodating unit 31, transports it to the stage 10, and places it thereon. The transport unit 40 also transports the substrate P with the groove P1 formed therein from the stage 10 to the second substrate accommodating unit 32.

The means by which the transport unit 40 holds the substrate P is not particularly limited, and may, for example, adsorb and hold the top surface of the substrate P, grip the substrate P in the thickness direction, or grip the outer edge of the substrate P. The transport unit 40 of this embodiment is configured to be capable of movement within the XY plane and of rising and lowering in the Z direction (a direction perpendicular to the X and Y directions), and adsorbs and holds the top surface of the substrate P, transporting it so that the top surface of the stage 10 (the surface on which the substrate P is placed) and the surface of the substrate P are parallel.

[Photography Department]
The photographing section includes, for example, a known camera 50, and photographs the substrate P being transported by the transport section 40. The transport section 40 transports the substrate P so that it passes through an imaging area of the camera 50 of the photographing section between the first substrate accommodation section 31 and the stage 10. The camera 50 is preferably positioned so as to photograph the underside of the substrate P being transported.

The camera 50 may, for example, photograph the positions of two markings formed on the underside of the substrate P, or, if the substrate P is substantially rectangular, may photograph the positions of two corners or one side. By photographing the substrate P in this way, it is possible to confirm the orientation of the above-mentioned plane (X-Y plane) of the substrate P being transported to the stage 10 (the inclination with respect to the X or Y direction when viewed in the thickness direction of the substrate P (viewed in the Z direction)).

〔stage〕
The stage 10 moves the substrate P placed by the transport unit 40 in the XY directions. The stage 10 moves the substrate P in the XY directions while the laser light irradiation unit 20 irradiates the substrate P with laser light, thereby forming a groove P1 on the surface of the substrate P. The stage 10 is not particularly limited, and may be a known linear stage or the like. The stage 10 is configured to be capable of moving simultaneously in two directions, the X direction and the Y direction. That is, the stage 10 can move in any direction within the XY plane. The stage 10 adjusts the relative position of the substrate P with respect to the laser light L irradiated by the laser light irradiation unit 20 by moving in any direction within the XY plane. The means by which the stage 10 holds the substrate P is not particularly limited, and may hold the lower surface of the substrate P by suction, for example.

The movement speed of the stage 10 (the speed at which the groove P1 is formed in at least one of the X and Y directions) is preferably 80 mm/s or more. The lower limit of the movement speed may be 100 mm/s, 150 mm/s, or 200 mm/s. The upper limit of the movement speed is not particularly limited and may be, for example, 1000 mm/s, 800 mm/s, or 500 mm/s. By setting the movement speed of the stage 10 within the above range, the groove P1 can be formed efficiently.

[Control Unit]
The control unit receives the image of the substrate P captured by the imaging unit, detects the orientation of the substrate P, and controls the movement of the stage 10 based on the detected orientation. The control unit may control the irradiation of the laser light from the laser light irradiation unit 20 and the cessation of the irradiation, in addition to controlling the movement of the stage 10.

For example, if the substrate P is substantially rectangular and a groove P1 (groove P1 in the X direction) parallel to one side of the substrate P is to be formed, the control unit, when determining that the side is parallel to the X direction (the substrate P does not have the above-mentioned inclination), causes the laser light irradiation unit 20 to irradiate the laser light while moving the stage 10 so that the substrate P moves a predetermined distance only in the X direction. If the control unit, when determining that the side is not parallel to the X direction (the substrate P has the above-mentioned inclination), moves the stage 10 in the X direction and also in the Y direction so as to follow the inclination with respect to the X direction (in the direction of the detected orientation) to form a groove P1 parallel to the side. Similarly, when forming a groove P1 (groove P1 in the Y direction) perpendicular to the one side, if the control unit determines that the one side and the Y direction are perpendicular (the substrate P does not have the above-mentioned inclination), it moves the stage 10 only in the Y direction, and if the control unit determines that the one side and the Y direction are not perpendicular (the substrate P has the above-mentioned inclination), it moves the stage 10 in the X direction as well as the Y direction to form a groove P1 perpendicular to the one side.

For example, if the stage on which the substrate is placed is configured to be rotatable in a plane parallel to the surface of the substrate in order to adjust (correct) the orientation of the substrate, the weight of the stage may increase and the movement speed may decrease. Adjusting the orientation of the substrate may also increase the tact time (the time it takes to complete the formation of grooves in the substrate removed from the substrate storage unit). In this laser dicing device, the control unit controls the stage 10 to move along the orientation of the substrate P and does not include a mechanism (member) for adjusting the orientation of the substrate P, so that the configuration can be simplified to reduce costs and improve processing speed, and by not adjusting the orientation of the substrate P, the efficiency of forming the grooves P1 can be improved and the tact time can be reduced.

[Laser light irradiation unit]
The laser light irradiation unit 20 includes a pulsed fiber laser (not shown) and irradiates the substrate P placed on the stage 10 with laser light L. The laser light irradiation unit 20 includes a laser emission unit 21 including the pulsed fiber laser, and a light guiding unit 22 that guides the pulsed laser light emitted from the laser emission unit 21 and irradiates it toward the substrate P. The light guiding unit 22 includes a reflecting mirror (not shown) that reflects the pulsed laser light toward the surface of the substrate P, a lens (not shown) that adjusts the spot diameter of the pulsed laser light (laser light L) on the surface of the substrate P, and the like.

When a continuous wave laser beam is irradiated onto the surface of the substrate, the surface is melted by the heat of the laser energy, and the surface of the groove (the surface where the laser beam is irradiated) is likely to be blackened. In this blackened portion (melted portion), the bonding strength with the electrode material is reduced, and the electrode formed from this electrode material may peel off. By irradiating the surface with a pulsed laser beam, thermal melting due to the laser energy is suppressed, blackening of the surface of the groove P1 formed can be suppressed, and the bonding strength with the electrode material can be sufficient to suppress the electrode formed on the surface from peeling off. In addition, by using a pulsed laser beam, the absorption efficiency of the laser energy in the substrate P is improved, the fracture (drilling) of the surface is promoted, and the groove P1 can be easily formed to a sufficient depth while suppressing the increase in the width of the groove P1. In addition, by improving the absorption efficiency of the laser energy, the generation of burrs on the surface (maximum height Rz on the surface) can be effectively suppressed, and the bonding strength with the electrode material can be improved to further suppress the electrode from peeling off. Pulsed fiber lasers amplify light within the optical fiber, and the optical fiber provides high cooling efficiency, making it easy to increase the output of the pulsed laser light, stably irradiating the laser light L, improving maintainability, extending the life span, and reducing running costs. In addition, even if the peak output of the pulsed laser light is increased, the output stability is excellent, so slippage can be effectively suppressed, and grooves P1 that are narrow and sufficiently deep can be reliably and easily formed.

The average output of the laser light L emitted by the pulsed fiber laser is preferably 70 W or more. The lower limit of the average output may be 80 W, 90 W, or 100 W. The upper limit of the average output is not particularly limited and may be 300 W, 250 W, or 200 W. By keeping the average output within the above range, a groove P1 of sufficient depth can be easily formed and blackening of the end surface can be effectively suppressed.

The peak output of the laser light L is preferably 7 kW or more. The lower limit of the peak output may be 8 kW, 9 kW, or 10 kW. The upper limit of the peak output is not particularly limited and may be 20 kW, 18 kW, or 15 kW.

The laser light L of the pulsed fiber laser may be emitted in microsecond (μs) pulses, nanosecond (ns) pulses, picosecond (ps) pulses, or femtosecond (fs) pulses. Specifically, the pulse width of the laser light L emitted by the pulsed fiber laser may be 2.0 μs or less. The upper limit of the pulse width may be 1.5 μs, 1.0 μs, or 0.5 μs. The lower limit of the pulse width is not particularly limited and may be 10 fs, 10 ps, or 10 ns. By setting the pulse width within the above range, a groove P1 of sufficient depth can be more easily formed, and blackening of the surface can be more effectively suppressed.

The repetition frequency of the laser light L emitted by the pulsed fiber laser is not particularly limited, and may be selected according to the output of the laser light L of the pulsed fiber laser, the pulse width, the material of the substrate, and the like. For example, the lower limit of the repetition frequency may be 50 kHz, 70 kHz, or 80 kHz. The upper limit of the repetition frequency is not particularly limited, and may be 500 kHz, 300 kHz, or 250 kHz. By setting the repetition frequency within the above range, a groove P1 of sufficient depth can be formed more easily, and blackening of the surface can be more effectively suppressed.

The wavelength of the laser light L emitted by the pulsed fiber laser is not particularly limited and may be selected depending on the material of the substrate, for example, 1059 nm or more and 1065 nm or less.

The upper limit of the spot diameter of the laser light L on the upper surface (irradiation surface of the laser light L) of the substrate P placed on the stage 10 may be 10 μm, 8 μm, or 7 μm. The lower limit of the spot diameter is not particularly limited and may be 1 μm or 2 μm. By setting the spot diameter within the above range, the absorption efficiency of the laser energy on the irradiation surface of the substrate P can be increased, and a groove P1 of sufficient depth can be formed while suppressing an increase in width.

The upper limit of the width of the groove P1 on the surface of the substrate P is preferably 40 μm, more preferably 35 μm, and even more preferably 30 μm. The lower limit of the width of the groove P1 is not particularly limited and may be, for example, 5 μm or 10 μm. By setting the width of the groove P1 within the above range, it is possible to improve the ease of singulating the substrate P while reducing loss of the substrate P (portions that cannot be used as singulated substrates).

The depth of the grooves P1 formed in the substrate P by the laser dicing device is preferably 30 μm or more. The lower limit of the depth of the grooves P1 may be 35 μm, 40 μm, 45 μm, or 50 μm. The upper limit of the depth of the grooves P1 is not particularly limited and may be 200 μm, 180 μm, or 150 μm. By setting the depth of the grooves P1 within the above range, the substrate P can be more easily singulated.

The maximum height Rz of the inner surface of the groove P1 formed by the laser dicing device (surface irradiated with the laser light L) is preferably 18 μm or less. The upper limit of the maximum height Rz may be 15 μm, 12 μm, or 10 μm. The lower limit of the maximum height Rz is not particularly limited and may be 2 μm, 3 μm, or 5 μm. By setting the maximum height Rz of the inner surface of the groove P1 within the above range, peeling of the electrode formed on the surface, for example, can be effectively suppressed. Note that the maximum height Rz means a value measured in accordance with JIS B0601:2013.

[Other embodiments]
The above-mentioned embodiment does not limit the configuration of the present invention. Therefore, the above-mentioned embodiment may omit, replace or add components of each part of the above-mentioned embodiment based on the description in this specification and common technical knowledge, and it should be understood that all of these are within the scope of the present invention.

The present disclosure will be further explained below with reference to examples, but the present disclosure is not limited to these examples.

A pulsed fiber laser with an average output of 20 W (TruPulse 1002 nano, manufactured by TRUMPF Laser UK) and a pulsed fiber laser with an average output of 100 W (TruPulse 1010 nano, manufactured by TRUMPF Laser UK) were used to form grooves on the surface of an alumina ceramic substrate. The laser light had a pulse width of 200 ns, a wavelength of 1064 μm, and a spot diameter of 5 μm. The results are shown in Table 1. In Table 1, "output [W]" refers to the average output value of the output port of the pulsed fiber laser, and "current value [%]" refers to the output adjustment parameter inside the laser oscillator.

With a pulsed fiber laser with an average output of 100 W (Test Examples 1 to 3), a groove with a depth of 40 μm or more could be formed even with a processing speed (movement speed of the laser light on the substrate surface) of 200 mm/s, and a groove with a depth of 50 μm or more could be formed by setting the processing speed to 150 mm/s or less. In addition, in Test Examples 1 to 3, the grooves could be formed with a sufficiently deep depth and a narrow width of 25 μm or less, and no slippage was observed. The maximum height Rz of the inner surface of the above grooves was 10 μm or less in all cases, and no blackening was observed. With a pulsed fiber laser with an average output of 20 W (Test Examples 4 to 6), a groove with a depth of 40 μm or more could not be formed unless the processing speed was 70 mm/s or less. In Test Example 4, where the processing speed was 70 mm/s, the grooves could be formed with a depth of 40 μm or more, but the width could not be made 25 μm or less.

The laser dicing device according to one aspect of the present disclosure can efficiently form grooves on the surface of a substrate, making it suitable for use in semiconductor chip manufacturing equipment, etc.

REFERENCE SIGNS LIST 10 stage 20 laser light irradiation section 21 laser emission section 22 light guide section 31 first substrate housing section 32 second substrate housing section 40 transport section 50 imaging section L laser light P substrate P1 groove

Claims (4)

A laser dicing device that forms grooves for dividing a substrate by irradiating the substrate with laser light,
A substrate housing section for housing a plurality of substrates;
a stage on which the substrate is placed;
a transport unit that transports a substrate from the substrate accommodation unit to the stage;
an imaging unit that images the substrate being transported by the transport unit;
a laser light irradiation unit that irradiates a laser light onto the substrate placed on the stage;
a control unit that moves a stage on which the substrate is placed along a direction in which the grooves are formed while maintaining an orientation of the stage in a plane parallel to the surface of the substrate;
The substrate is made of alumina ceramics or aluminum nitride ceramics,
The laser light irradiation unit includes a pulsed fiber laser,
The control unit detects an orientation of the substrate within the plane from an image captured by the imaging unit, and controls movement of the stage based on the detected orientation . The laser dicing device according to claim 1, wherein the average output of the laser light emitted by the pulsed fiber laser is 70 W or more. The laser dicing device according to claim 1, wherein the pulse width of the laser light emitted by the pulsed fiber laser is 10 ns or more and 2.0 μsec or less. A method for manufacturing a substrate having grooves for singulation, comprising the steps of:
removing one substrate from a substrate accommodating unit accommodating a plurality of substrates;
transporting the removed substrate to a stage;
taking an image of the substrate being transported;
placing the transported substrate on the stage;
and a step of irradiating the substrate moved by the stage with a laser beam to form a groove having a depth of 30 μm or more and a width of 40 μm or less,
The substrate is made of alumina ceramics or aluminum nitride ceramics,
The laser light is emitted from a pulsed fiber laser,
A method for manufacturing a substrate in which, in the forming process, an orientation of the substrate in a plane parallel to the surface of the substrate is detected from the image captured in the photographing process, the movement of the stage is controlled based on the detected orientation, and the stage moves along the groove formation direction while maintaining its orientation in the plane.

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