Laser dicing apparatus and substrate manufacturing method

Abstract

An object of the present disclosure is to provide a laser dicing device capable of easily obtaining a substrate having a desired groove.SOLUTION: A laser dicing device according to one aspect of the present disclosure is a laser dicing device that forms a groove for singulating a substrate by irradiating the substrate with laser light, the laser dicing device including a stage on which the substrate is placed, and a laser light irradiator that irradiates the substrate placed on the stage with the laser light, wherein the laser light irradiator includes a pulse fiber laser.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laser dicing apparatus and a method for manufacturing a substrate. [Background technology]

[0002] Semiconductor devices are mounted on semiconductor device chips and installed in various products. A technique for obtaining semiconductor device chips by dividing a semiconductor substrate such as a wafer is known (Japanese Patent Laid-Open Publication No. 2023-091141). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-091141 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, grooves are formed along a planned dividing line in a wafer by cutting with a blade or ablation processing using laser light irradiation, and the wafer is then divided to obtain semiconductor device chips. Cutting a wafer with a blade requires cleaning of chips generated by cutting and replacing worn blades, which may hinder efficient production of semiconductor device chips. Ablation processing of a wafer using laser light irradiation does not require wafer cleaning or blade replacement, but high-speed processing may result in insufficient groove depth. Furthermore, burrs may be generated in the formed grooves due to laser energy or heat-induced blackening. Reducing the output of the laser light to prevent burrs or blackening may result in slippage (partial lack of groove formation), and reducing the processing speed (the speed at which the grooves are formed) to prevent slippage may reduce the efficiency of groove formation.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a laser dicing apparatus that can easily obtain a substrate having a desired groove. [Means for solving the problem]

[0006] A 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 it 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. [Effects of the Invention]

[0007] A laser dicing apparatus according to one aspect of the present disclosure can easily obtain a substrate having a desired groove. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic plan view showing a laser dicing apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic front view of the laser dicing apparatus of FIG. [Figure 3] FIG. 3 is a schematic plan view showing a state in which the laser dicing apparatus of FIG. 1 forms grooves in a substrate. [Figure 4] FIG. 4 is a schematic front view of the laser dicing apparatus of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (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 it 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.

[0011] In this laser dicing device, a laser light irradiation unit that irradiates 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. Because pulsed fiber lasers have high energy conversion efficiency, they can irradiate laser light with a high peak intensity, making it easy to form sufficiently deep grooves in the substrate. Furthermore, because laser light with a high peak intensity is irradiated in a short time, the substrate surface to form the grooves is fractured in a short time, suppressing burrs in the grooves. Furthermore, because heating of the substrate surface is suppressed, blackening of the formed grooves is also suppressed.

[0012] (2) In the above (1), the average power of the laser light emitted by the pulse fiber laser may be equal to or greater than 70 W. By setting the average power of the laser light to equal to or greater than 70 W, the processing speed can be improved, and the efficiency of forming grooves of sufficient depth can be improved.

[0013] (3) In the above (1) or (2), the pulse width of the laser light emitted by the pulse fiber laser may be 2.0 μsec or less. By setting the pulse width of the laser light to 2.0 μsec or less, it is possible to further improve the reliability of forming grooves of sufficient depth.

[0014] (4) A method for manufacturing a substrate according to one embodiment 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, wherein the laser light is emitted from a pulsed fiber laser.

[0015] Since the grooves are formed in the substrate by the laser light emitted from the pulsed fiber laser, grooves with a depth of 30 μm or more can be easily and reliably formed, making it possible to easily obtain a substrate having grooves deep enough for individualization, and easily suppressing burrs and blackening on the surface (inner surface) of the grooves.

[0016] (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 the substrate by irradiating it with laser light, and includes a substrate accommodating section that accommodates multiple substrates, a stage that moves in one direction within a plane parallel to the surface of the placed substrate and in a direction perpendicular to the one direction, a transport section that transports the substrate from the substrate accommodating section to the stage, an imaging section that photographs the substrate transported by the transport section, a laser light irradiation section that irradiates laser light onto the substrate placed on the stage, and a control section that controls movement of the stage, wherein the control section detects the orientation of the substrate within the plane from an image captured by the imaging section and controls movement of the stage based on the detected orientation.

[0017] 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 substrate in the desired orientation.

[0018] [Details of the Mode for Carrying Out 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, and arrangement of each component (member) may differ from the actual ones.

[0019] <Laser dicing equipment> 1 to 4, the laser dicing apparatus 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 apparatus also includes a substrate accommodation unit that accommodates multiple substrates P, a transport unit 40 that transports the substrates P from the substrate accommodation unit to the stage 10, an imaging unit that photographs the substrates 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) within a plane parallel to the surfaces (top and bottom surfaces) of the placed substrate P and in a direction (Y direction) perpendicular to the one direction. The stage 10, 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).

[0020] <Substrate> Grooves P1 with a depth of 30 μm or more are formed on the top surface of the substrate P (the surface opposite to the surface placed on the stage 10) by the laser dicing device for singulation (division into multiple small pieces). This substrate P can be obtained by a manufacturing method including the steps of placing the substrate P on the stage 10 and irradiating the substrate P, which is being moved by the stage 10, with laser light L to form grooves P1 with a depth of 30 μm or more. The laser light L is emitted from a pulsed fiber laser. A plurality of grooves P1 perpendicular to one another are formed on the top surface of the substrate P.

[0021] The substrate P is not particularly limited as long as it is a substrate that can be 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. FIGS. 1 to 4 show a rectangular semiconductor substrate P. At least a portion of the end face (dividing surface) of the singulated substrate P is used as an electrode. Specifically, the substrate P is singulated by applying an electrode material (not shown) onto the formed grooves P1, or by forming the grooves P1 and singulating the substrate P, and then applying an electrode material to form electrodes on some or all of the end face.

[0022] The material of the substrate P is not particularly limited as long as it is possible to form grooves P1 by irradiating it with laser light L, and may be, for example, alumina (Al2O3) 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.

[0023] [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 groove P1 is formed, and a second substrate accommodating section 32 that accommodates the substrate P after the groove P1 has been formed.

[0024] 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 apparatus, or may be fixed so that they cannot be detached. The laser dicing apparatus may include multiple first substrate accommodating sections 31 and multiple second substrate accommodating sections 32.

[0025] [Transportation section] The transport unit 40 takes out one of the plurality of substrates P accommodated in the first substrate accommodation unit 31, transports it to the stage 10, and places it thereon. The transport unit 40 also transports the substrate P having the groove P1 formed therein from the stage 10 to the second substrate accommodation unit 32.

[0026] The means by which the transport unit 40 holds the substrate P is not particularly limited, and for example, the transport unit 40 may hold the upper surface of the substrate P by suction, may grip the substrate P in the thickness direction, or may grip the outer edge of the substrate P. The transport unit 40 of this embodiment is configured to be able to move within the XY plane and to move up and down in the Z direction (a direction perpendicular to the X and Y directions), and transports the substrate P by suction and holds the upper surface of the substrate P so that the upper surface of the stage 10 (the surface on which the substrate P is placed) and the surface of the substrate P are parallel.

[0027] [Photography Department] The photographing unit includes, for example, a known camera 50, and photographs the substrate P being transported by the transport unit 40. The transport unit 40 transports the substrate P so that it passes through the photographing area of ​​the camera 50 of the photographing unit between the first substrate accommodation unit 31 and the stage 10. The camera 50 is preferably positioned so as to photograph the underside of the substrate P being transported.

[0028] For example, camera 50 may photograph the positions of two markings formed on the underside of substrate P, or, in the case of a substantially rectangular substrate P, may photograph the positions of two corners or one side. By photographing substrate P in this way, it is possible to confirm the orientation of the plane (XY plane) of substrate P being transported to stage 10 (the tilt with respect to the X direction or Y direction when viewed in the thickness direction of substrate P (viewed in the Z direction)).

[0029] 〔stage〕 The stage 10 moves the substrate P placed by the transport unit 40 in the X and Y directions. While the stage 10 moves the substrate P in the X and Y directions, 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, for example. The stage 10 is configured to be able to move simultaneously in two directions, the X and Y directions. That is, the stage 10 can move in any direction within the X and Y plane. By moving the stage 10 in any direction within the X and Y 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. The means by which the stage 10 holds the substrate P is not particularly limited and, for example, the stage 10 may hold the lower surface of the substrate P by suction.

[0030] 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.

[0031] [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. In addition to controlling the movement of the stage 10, the control unit may also control the irradiation of laser light by the laser light irradiation unit 20 and the cessation of the irradiation.

[0032] 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 has no inclination), causes the laser light irradiation unit 20 to irradiate 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 inclination), moves the stage 10 in the X direction and also in the Y direction so as to follow the inclination relative to the X direction (in the direction of the detected orientation), thereby forming 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.

[0033] 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, reducing the movement speed. Adjusting the orientation of the substrate may also increase the takt time (the time it takes to complete the formation of grooves in a substrate removed from a substrate storage unit). Because the control unit of the laser dicing device controls the movement of the stage 10 to match the orientation of the substrate P and does not include a mechanism (component) for adjusting the orientation of the substrate P, the device can simplify its configuration, reduce costs, and increase processing speed. Not adjusting the orientation of the substrate P improves the efficiency of forming grooves P1, reducing the takt time.

[0034] [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 guide unit 22 that guides the pulsed laser light emitted from the laser emission unit 21 and irradiates it toward the substrate P. The light guide 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.

[0035] When a continuous-wave laser beam is irradiated onto the surface of a substrate, the surface melts due to the heat of the laser energy, and the surface of the groove (the surface irradiated with the laser beam) is likely to blacken. In this blackened portion (melted portion), the bond strength with the electrode material is reduced, which can lead to peeling of the electrode formed from this electrode material. By irradiating the surface with a pulsed laser beam, thermal melting due to the laser energy is suppressed, and blackening of the surface of the formed groove P1 can be suppressed. By ensuring sufficient bond strength with the electrode material, peeling of the electrode formed on the surface can be suppressed. Furthermore, using a pulsed laser beam improves the absorption efficiency of the laser energy in the substrate P, promoting fracture (excavation) of the surface. This allows for the easy formation of a groove P1 with sufficient depth while suppressing an increase in the width of the groove P1. Furthermore, improving the absorption efficiency of the laser energy effectively suppresses the generation of burrs on the surface (maximum height Rz on the surface), improving the bond strength with the electrode material, and further suppressing peeling of the electrode. The pulsed fiber laser amplifies light within the optical fiber and has high cooling efficiency due to the optical fiber, so it is easy to increase the output power of the emitted pulsed laser light, and it can stably irradiate the laser light L, which allows for improved maintainability, a longer life, and lower running costs. Furthermore, because the output stability is excellent even when the peak output power of the pulsed laser light is increased, slippage can be effectively suppressed, and grooves P1 having a narrow width and sufficient depth can be reliably and easily formed.

[0036] The average output power of the laser light L emitted by the pulsed fiber laser is preferably 70 W or more. The lower limit of the average output power may be 80 W, 90 W, or 100 W. The upper limit of the average output power is not particularly limited and may be 300 W, 250 W, or 200 W. By setting the average output power within the above range, grooves P1 of sufficient depth can be easily formed, and blackening of the end face can be effectively suppressed.

[0037] 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.

[0038] The laser light L from the pulsed fiber laser may be emitted as a microsecond (μs) pulse, a nanosecond (ns) pulse, a picosecond (ps) pulse, or a femtosecond (fs) pulse. Specifically, the pulse width of the laser light L emitted by the pulsed fiber laser is preferably 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, grooves P1 of sufficient depth can be more easily formed and blackening of the surface can be more effectively suppressed.

[0039] The repetition frequency of the laser light L emitted by the pulsed fiber laser is not particularly limited, and may be selected depending on the output of the laser light L from the pulsed fiber laser, the pulse width, the material of the substrate, etc. 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, grooves P1 of sufficient depth can be formed more easily, and blackening of the surface can be more effectively suppressed.

[0040] The wavelength of the laser light L emitted by the pulse fiber laser is not particularly limited, and may be selected depending on the material of the substrate, for example, and may be 1059 nm or more and 1065 nm or less.

[0041] The upper limit of the spot diameter of the laser light L on the upper surface (surface irradiated with 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, it is possible to increase the efficiency of laser energy absorption on the irradiated surface of the substrate P, and to form a groove P1 of sufficient depth while suppressing an increase in width.

[0042] 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 dividing the substrate P into individual pieces while reducing loss of the substrate P (portions that cannot be used as individual substrates).

[0043] 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 divided into individual pieces.

[0044] The maximum height Rz of the inner surface of the groove P1 formed by the laser dicing device (the 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 can be effectively suppressed, for example. Note that the maximum height Rz refers to a value measured in accordance with JIS B0601:2013.

[0045] [Other embodiments] The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as belonging to the scope of the present invention. [Example]

[0046] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to these examples.

[0047] Grooves were formed on the surface of an alumina ceramic substrate using a pulsed fiber laser (TruPulse 1002 nano, manufactured by TRUMPF Laser UK) with an average power of 20 W and a pulsed fiber laser (TruPulse 1010 nano, manufactured by TRUMPF Laser UK) with an average power of 100 W. 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. Note that "output [W]" in Table 1 indicates the average output value of the output port of the pulsed fiber laser, and "current value [%]" indicates the output adjustment parameter inside the laser oscillator.

[0048] [Table 1]

[0049] With a pulsed fiber laser with an average output of 100 W (Test Examples 1 to 3), grooves with a depth of 40 μm or more could be formed even when the processing speed (the moving speed of the laser beam on the substrate surface) was 200 mm / s. Grooves with a depth of 50 μm or more could be formed by setting the processing speed to 150 mm / s or less. Furthermore, in Test Examples 1 to 3, grooves with a sufficiently deep depth and a narrow width of 25 μm or less could be formed, and no slippage was observed. The maximum height Rz of the inner surface of each of the grooves was 10 μm or less, and no blackening was observed. With a pulsed fiber laser with an average output of 20 W (Test Examples 4 to 6), grooves with a depth of 40 μm or more could only be formed when the processing speed was 70 mm / s or less. In Test Example 4, where the processing speed was 70 mm / s, grooves with a depth of 40 μm or more could be formed, but a width of 25 μm or less could not be formed. [Industrial Applicability]

[0050] A laser dicing device according to one aspect of the present disclosure can efficiently form grooves on a substrate surface, and is therefore suitable for use in semiconductor chip manufacturing equipment, etc. [Explanation of symbols]

[0051] 10 stages 20 Laser light irradiation unit 21 Laser emission part 22 Light guide section 31 First substrate accommodating section 32 Second board housing section 40 Conveying section 50 Photography Department L laser light P board P1 groove

Claims

1. A laser dicing device that forms grooves for dividing a substrate into individual pieces by irradiating the substrate with laser light, a stage on which a substrate is placed; a laser light irradiation unit that irradiates a laser light onto the substrate placed on the stage; Equipped with The laser dicing device, wherein the laser light irradiation unit includes a pulsed fiber laser.

2. 2. 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.

3. 2. The laser dicing device according to claim 1, wherein the pulse width of the laser light emitted by the pulse fiber laser is 2.0 μsec or less.

4. A method for manufacturing a substrate having grooves for singulation, comprising: placing the substrate on a stage; a step of irradiating the substrate being moved by the stage with laser light to form a groove having a depth of 30 μm or more; Equipped with The method for manufacturing a substrate, wherein the laser light is emitted from a pulsed fiber laser.

5. A laser dicing device that forms grooves for dividing a substrate into individual pieces by irradiating the substrate with laser light, a substrate accommodating section for accommodating a plurality of substrates; a stage that moves in one direction within a plane parallel to the surface of the placed substrate and in a direction perpendicular to the one direction; 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 for controlling the movement of the stage; Equipped with The control unit detects the orientation of the substrate within the plane from the image captured by the imaging unit, and controls the movement of the stage based on the detected orientation.

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