Laser dicing device and method for manufacturing substrate

Abstract

An object of the present disclosure is to provide a laser dicing apparatus 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.

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 (JP 2023-091141 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-091141 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, grooves are formed along the planned dividing lines in a 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 a wafer with a blade, chips for semiconductor devices may not be efficiently produced because it is necessary to clean chips generated by cutting and replace worn blades. In ablation processing of a wafer by irradiating laser light, cleaning of the wafer and replacement of the blade are not required, but if the processing is performed at a high speed, a sufficiently deep groove may not 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 in order to suppress the occurrence of burrs or blackening, slips (partial failure to form grooves) may occur, and if the processing speed (speed at which grooves are formed) is reduced in order to suppress slips, the efficiency of forming grooves may decrease.

[0005] In consideration of the above-mentioned 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 apparatus according to one aspect of the present disclosure made to solve the above problems is a laser dicing apparatus that forms grooves for singulating a substrate by irradiating laser light, and includes a stage for placing the substrate on 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. Effect 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 description 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. [Diagram 2] FIG. 2 is a schematic front view of the laser dicing apparatus of FIG. [Diagram 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 PREFERRED EMBODIMENTS

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

[0010] (1) 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 the substrate with laser light, and includes a stage for placing the substrate thereon and a laser light irradiation unit that irradiates the substrate placed on the stage with laser light, the laser light irradiation unit including a pulsed fiber laser.

[0011] In the laser dicing device, a laser light irradiation unit that irradiates laser light includes a pulse fiber laser, and the laser light emitted by the pulse fiber laser is irradiated onto a substrate placed on a stage to form grooves for singulation. Since the pulse 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 for forming 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.

[0012] (2) In the above (1), the average output of the laser light emitted by the pulse fiber laser may be equal to or greater than 70 W. By setting the average output of the laser light to equal to or greater than 70 W, the processing speed can be improved, and efficiency in 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 a groove 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 moving 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.

[0015] Since the grooves in the substrate are formed by the laser light emitted by the pulsed fiber laser, grooves having 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 also easily suppressing burrs and blackening on the surface (inner surface) of the grooves.

[0016] (5) A laser dicing apparatus according to one embodiment of the present disclosure is a laser dicing apparatus that forms grooves in a substrate for singulating by irradiating the substrate with laser light, and includes a substrate accommodating section that accommodates a plurality of substrates, a stage that moves in one direction within a plane parallel to a surface of the substrate placed thereon 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 the substrate placed on the stage with laser light, and a control section that controls movement of the stage, wherein the control section detects an orientation of the substrate in the plane from an image captured by the imaging section, and controls movement of the stage based on the detected orientation.

[0017] In the laser dicing device, a control unit that controls movement of a stage detects the orientation of the substrate in a plane parallel to the surface of the substrate from an image captured by an imaging unit, and controls movement of the stage based on the detected orientation. Since the stage moves along the orientation of the substrate without correcting the orientation of the substrate, the laser dicing device can efficiently form grooves in the substrate in a desired orientation.

[0018] [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.

[0019] <Laser dicing equipment> 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 accommodated in a housing (not shown).

[0020] <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 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 is divided into individual pieces 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 substrate P for semiconductor use. At least a part of the end face (dividing face) of the divided substrate P is used as an electrode. Specifically, the substrate P is divided into individual pieces by coating an electrode material (not shown) on the formed grooves P1, or by forming the grooves P1 and dividing the substrate P into individual pieces, and then coating an electrode material to form an electrode on a part or all of the end face.

[0022] The material of the substrate P is not particularly limited as long as the grooves P1 can be formed therein by irradiation with the 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 the size 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 is formed.

[0024] The manner in which the substrate accommodating sections 31, 32 accommodate the multiple substrates P is not particularly limited, and for example, the 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 as not to be detachable. The laser dicing apparatus may include a plurality of first substrate accommodating sections 31 and a plurality of second substrate accommodating sections 32.

[0025] [Transportation section] The transport unit 40 takes out one of the multiple substrates P accommodated in the first substrate accommodating portion 31, transports it to the stage 10, and places it thereon. In addition, the transport unit 40 transports the substrate P having the groove P1 formed therein from the stage 10 to the second substrate accommodating portion 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 suction-hold the upper surface of the substrate P, 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 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 transports the substrate P by suction-holding the upper surface thereof 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 to each other.

[0027] [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.

[0028] The camera 50 may, for example, photograph the positions of two markings formed on the lower surface of the substrate P, or, in the case of a substantially rectangular substrate P, 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 (XY plane) of the substrate P transported to the stage 10 (the inclination with respect to the X direction or Y direction when viewed in the thickness direction of the substrate P (viewed in the Z direction)).

[0029] 〔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.

[0030] The movement speed of the stage 10 (the speed at which the groove P1 is formed in at least one of the X direction and the Y direction) 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. 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.

[0032] For example, when 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, if the control unit determines that the side is parallel to the X direction (the substrate P has no inclination), it 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 determines that the side is not parallel to the X direction (the substrate P has the inclination), it 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), thereby forming a groove P1 parallel to the side. Similarly, when forming a groove P1 (groove P1 in the Y direction) perpendicular to the above-mentioned side, if the control unit determines that the above-mentioned side and the Y direction are perpendicular (there is no inclination in the substrate P), it moves the stage 10 only in the Y direction, and if the control unit determines that the above-mentioned side and the Y direction are not perpendicular (there is an inclination in the substrate P), it moves the stage 10 in the X direction as well as in the Y direction, to form a groove P1 perpendicular to the above-mentioned 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 and the moving 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). The laser dicing device has the control unit control 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 the 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.

[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 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.

[0035] 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 of this electrode material may peel off. By irradiating the surface with a pulsed laser beam, the thermal melting caused by the laser energy is suppressed, and blackening of the surface of the groove P1 formed can be suppressed, and the bonding strength with the electrode material can be made 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, and the fracturing (drilling) of the surface is promoted, and the groove P1 can be easily formed to a sufficient depth while suppressing an 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. Since the pulse fiber laser amplifies light within the optical fiber and the optical fiber has high cooling efficiency, it is easy to increase the output of the pulse laser light emitted, and the laser light L can be stably emitted, which improves maintainability, extends the life, and reduces running costs. Furthermore, since the output stability is excellent even when the peak output of the pulse laser light is improved, 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 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 setting the average output within the above range, a groove 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 of the pulse fiber laser may be emitted with 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 pulse 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, a groove P1 with a 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 pulse fiber laser is not particularly limited, and may be selected according to the output of the laser light L of the pulse 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.

[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 absorption of laser energy on the irradiated surface of the substrate P, and it is possible 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 singulating the substrate P while reducing loss of the substrate P (portions that cannot be used as singulated 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 (surface irradiated with the laser light L) of the groove P1 formed by the laser dicing device 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, for example, peeling of the electrode formed on the surface can be effectively suppressed. Note that the maximum height Rz means a value measured in accordance with JIS B0601:2013.

[0045] [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. EXAMPLES

[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 output of 20 W and a pulsed fiber laser (TruPulse 1010 nano, manufactured by TRUMPF Laser UK) with an average output 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. 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.

[0048] [Table 1]

[0049] With a pulse fiber laser having an average output of 100 W (Test Examples 1 to 3), a groove having a depth of 40 μm or more could be formed even when the processing speed (the moving speed of the laser light on the substrate surface) was 200 mm / s, and a groove having 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 groove could be formed with a sufficiently deep depth and a narrow width of 25 μm or less, and no slip was observed. The maximum height Rz of the inner surface of the above groove was 10 μm or less in all cases, and no blackening was observed. With a pulse fiber laser having an average output of 20 W (Test Examples 4 to 6), a groove having 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, in which the processing speed was 70 mm / s, the groove could be formed with a depth of 40 μm or more, but the width could not be formed with a width of 25 μm or less. [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 board housing section 32 Second board housing section 40 Conveyor 50 Photography Department L Laser light P board P1 groove

Claims

1. 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 in a plane parallel to the surface of the substrate; Equipped with 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.

2. 2. The laser dicing device according to claim 1, wherein the average output of the laser light emitted by the pulse 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 10 ns or more and 2.0 μsec or less.

4. 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; 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; Equipped with 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.

Images