Method for manufacturing a substrate having micropores

Abstract

Compared to conventional techniques, this invention provides a method for manufacturing a substrate having micropores that can create large-diameter holes in a short amount of time. [Solution] A TGV formation technology is provided, which includes perforating a substrate with time-wavelength modulated laser pulses, and performing chemical etching on the through-vias formed by the perforations with a diameter of 1 μm or more, to manufacture a substrate having micropores.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a substrate having micropores. [Background Art]

[0002] Conventionally, TGV (Through-Glass Via) technology is known as a method for producing a substrate having micropores in the field of semiconductor manufacturing technology. TGV is a technology that modifies a glass substrate using a picosecond laser or a femtosecond laser, and then performs chemical etching to form holes in the modified portion. Regarding this type of technology, for example, Non-Patent Document 1 describes an example in which microchannels are produced by internal modification of glass with a femtosecond laser followed by selective etching.

[0003] Further, as a method for producing a substrate having micropores, as disclosed in Patent Document 1, the method comprises: (1) a step of preparing a substrate having a first surface and a second surface facing each other; (2) a step of irradiating the first surface of the substrate with a first laser having a wavelength transparent to the substrate to form a light-absorbing region extending from the first surface of the substrate along a stretching axis, wherein the first laser has a pulse width of 100 nanoseconds or less; (3) a step of irradiating the light-absorbing region with a second laser having a wavelength transparent to the substrate during at least a time overlapping with the irradiation time of the first laser to selectively remove the substrate in the light-absorbing region, wherein the second laser has a pulse width of 1 microsecond or more, and the second laser is incident on the first surface of the substrate at an incident angle of 5° or more and 50° or less with respect to the stretching axis of the light-absorbing region. A production method comprising the above steps is disclosed.

[0004] The technology described in Patent Document 1 can form holes in a substrate by using two lasers: a first laser consisting of an ultrashort pulse laser and a second laser consisting of a long pulse laser. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-89171 [Non-patent literature]

[0006] [Non-Patent Document 1] Andrius Marcinkevicius et al., Femtosecond laser-assisted three-dimensional microfabrication in silica, "OPTICS LETTERS", USA, Optical Society of America, March 1, 2001, Vol. 26, No. 5, pp. 277–279. [Overview of the project] [Problems that the invention aims to solve]

[0007] Incidentally, the above-mentioned techniques for forming micropores using laser processing and chemical etching had a problem: when performing the hole-making process using chemical etching, for example, forming a hole with a diameter of 50 μm could take about 8 hours, resulting in a long working time.

[0008] Furthermore, in the technique of forming micro-holes using the first and second lasers described above, there was a problem in that there was a limit to the diameter of the holes that could be made because the two lasers were irradiated onto the substrate coaxially.

[0009] The problem that this disclosure aims to solve is to provide a method for manufacturing a substrate having micropores that can create large-diameter holes in a shorter time compared to conventional technologies. [Means for solving the problem]

[0010] The method for manufacturing a substrate having micropores according to this disclosure is a TGV formation technology, which includes perforating the substrate with a time-wavelength modulated laser pulse, and performing chemical etching when the diameter of the through-vias formed by the perforation is 1 μm or more. In one embodiment of this manufacturing method, perforation is performed on the substrate using a time-waveform modulated laser pulse obtained by combining a first laser consisting of an ultrashort pulse laser and a second laser consisting of a long pulse laser. In one embodiment of this manufacturing method, the pore size is in the range of 1 μm to 30 μm. In one embodiment of this manufacturing method, the pulse width of the first laser is 100 femtoseconds to less than 100 picoseconds, and the pulse width of the second laser is 1 nanosecond to less than 1 millisecond. In one embodiment of this manufacturing method, the wavelengths of the first laser and the second laser are in the 1-micron range. In one embodiment of this manufacturing method, the first laser is irradiated, followed by the second laser. In one embodiment of this manufacturing method, the second laser is irradiated within 5 picoseconds after the first laser is irradiated. One embodiment of this manufacturing method involves irradiating with the second laser, followed by irradiating with the first laser. However, the irradiation time of the second laser is 1 nanosecond or more and less than 1 millisecond after the irradiation time of the first laser has ended. In one embodiment of this manufacturing method, the perforation is performed by coupling a ytterbium-doped solid-state laser as the first laser and a ytterbium-doped fiber laser as the second laser using coupling means including polarization coupling and wavelength coupling, integrating the two laser pulses optically coaxially, and using the time-wavelength modulated laser pulse. In one embodiment of this manufacturing method, the first laser is a laser that wavelength-converts a laser output in the 1-micron wavelength band and outputs at any wavelength including the second harmonic and the third harmonic, and the second laser is a solid-state laser that outputs in the 1-micron or 2-micron wavelength band. One embodiment of this manufacturing method is a method for manufacturing a substrate having micropores in which one or more micropores are formed, wherein the time-wavelength modulated laser pulse, consisting of the first laser and the second laser, is irradiated once per micropore. In one embodiment of this manufacturing method, the chemical etching is carried out using a solution mainly composed of a chemical substance containing hydrofluoric acid or potassium hydroxide. In one embodiment of this manufacturing method, drilling is performed using a single laser that emits a time-waveform modulated laser pulse having an ultrashort pulse portion with high peak power and a long pulse portion with low power. In one embodiment of this manufacturing method, drilling is performed with a time-wavelength modulated laser pulse in which the ultrashort pulse portion has been shortened by harmonic generation using a nonlinear optical crystal. In one embodiment of this manufacturing method, the thickness of the substrate is in the range of 50 μm to 1000 μm. [Effects of the Invention]

[0011] According to this disclosure, it is possible to provide a method for manufacturing a substrate having micropores that can create large-diameter holes of 50 μm or more in a short time compared to conventional technology. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing the basic configuration of a laser device according to the first embodiment of the present disclosure. [Figure 2] This is an explanatory diagram showing the relationship between the laser output and time in the laser device. [Figure 3] This is a cross-sectional view showing the pore shape of the substrate after chemical etching. [Figure 4] This is a cross-sectional view showing the pore shape of the substrate after chemical etching. [Figure 5] This graph shows the relationship between pore size and chemical etching time. [Figure 6] This is a schematic diagram showing the laser generating means of a laser apparatus according to a second embodiment of the present disclosure. [Figure 7]It is an explanatory diagram showing the relationship between laser output and time of the same laser device, where (a) is the output waveform of the LD, and (b) is the output waveform of the power amplifier. [Figure 8] It is a schematic diagram showing the basic configuration of the same laser device. [Figure 9] It is an explanatory diagram of wavelength conversion according to the third embodiment of the present disclosure. [Figure 10] It is a graph showing the relationship between fundamental wave intensity and harmonic intensity. Mode for Carrying Out the Invention

[0013] First Embodiment The method for manufacturing a substrate having micropores according to the present disclosure is suitable for application to, for example, TGV formation technology used in semiconductor manufacturing technology. Hereinafter, the first embodiment of the present disclosure will be described in detail.

[0014] First, a laser device used in the method for manufacturing a substrate having micropores according to the first embodiment will be described.

[0015] Figure 1 is a schematic diagram showing the basic configuration of the laser device 1. As shown in Figure 1, the laser device 1 used in TGV formation technology includes a first laser light source 2, a first beam expander 3, a first axicon lens 4, a first lens 5, a mirror 6, a beam splitter 7, an objective lens 8, a second laser light source 9, a second beam expander 10, a second axicon lens 11, and a second lens 12.

[0016] By using this laser device 1, one or more fine holes (through vias) can be formed in the substrate 21, which will be described later.

[0017] The first laser light source 2 has the function of emitting a first laser 2a (femtosecond laser), which is an ultrashort pulse laser, toward the first axicon lens 4 via the first beam expander 3.

[0018] The first beam expander 3 is used to expand or contract the diameter of the first laser 2a.

[0019] The first axicon lens 4 is a cone-shaped lens. Alternatively, a DOE (Diffractive Optical Element) or a spatial phase modulator can be used as a substitute optical element with equivalent functionality to the first axicon lens 4. The first axicon lens 4 focuses the laser beam toward the optical axis, thereby forming a Bessel beam in the space immediately behind the first axicon lens 4.

[0020] The first laser 2a emitted from the first axicon lens 4 travels through the first lens 5 and towards the mirror 6. The first lens 5 is composed of a single-element spherical plano-convex lens, an aspherical lens, or a lens in which multiple lenses are combined and fixed.

[0021] Mirror 6 reflects the first laser 2a and guides it to the beam splitter 7. The beam splitter 7 has the function of reflecting the first laser 2a and transmitting the second laser 9a, which will be described later. The beam splitter 7 also directs these two lasers toward the objective lens 8.

[0022] The objective lens 8 is the lens positioned closest to the substrate 21, which will be described later. The objective lens 8 is composed of a single-element spherical plano-convex lens, an aspherical lens, or a lens made up of multiple lenses combined and fixed together.

[0023] On the other hand, the second laser light source 9 has the role of emitting a second laser 9a (microsecond laser), which consists of a long-pulse laser, towards the second axicon lens 11 via the second beam expander 10.

[0024] The second beam expander 10 is used to expand or contract the diameter of the second laser 9a.

[0025] The second axicon lens 11 is a cone-shaped lens. Alternatively, a DOE (Diffractive Optical Element) or a spatial phase modulator can be used as a substitute optical element with equivalent functionality to the second axicon lens 11. The second axicon lens 11 focuses the laser beam toward the optical axis, thereby forming a Bessel beam.

[0026] The second laser 9a emitted from the second axicon lens 11 is guided to the beam splitter 7 via the second lens 12. The second lens 12 is composed of a single-element spherical plano-convex lens, an aspherical lens, or a lens in which multiple lenses are combined and fixed.

[0027] The first laser 2a and the second laser 9a then pass through the beam splitter 7 and the objective lens 8 before being irradiated onto the first surface 21a of the substrate 21, which will be described later.

[0028] It should be noted that embodiments without the axicon lens and DOE, which are characteristic of the above embodiments, are also possible. When the pulsed beams of the first laser 2a and the second laser 9a are not beam-shaped by an axicon lens, they are both Gaussian beams, and the depth of focus changes depending on the size of the focal point. The first beam is irradiated onto the first surface 21a of the substrate 21, which will be described later, at a focal point with a small beam waist on the order of 1 μm, and modifies the substrate 21 while maintaining a narrow, parallel beam of light while causing filamentation inside the substrate 21, which will be described later. The pulsed beam of the second laser 9a is beam-shaped to focus the beam waist on the order of 15 μm, and its depth of focus is set to approximately 1 mm, and it is irradiated so that its focal point is located inside the substrate 21, which will be described later.

[0029] The following describes the steps for carrying out the manufacturing method of the substrate having micropores according to this embodiment using the laser device 1 described above.

[0030] First, the operator prepares the substrate 21 to be processed (irradiated object). The material of the substrate 21 is transparent to the wavelengths of the first laser 2a and the second laser 9a, and is, for example, quartz glass.

[0031] The base material 21 is formed in the shape of a plate. The thickness of the substrate 21 is, for example, in the range of 50 μm to 1000 μm, and semiconductor materials are generally available on the market. When using such a substrate 21, as described later, to manufacture a TGV, the technology according to this embodiment is suitable for that purpose.

[0032] The base material 21 has a first surface 21a and a second surface 21b that are opposite to each other. The operator operates the laser device 1 to perform laser processing on the substrate 21, from the first surface 21a to the second surface 21b.

[0033] Therefore, the worker positions the substrate 21 such that the second surface 21b of the substrate 21 faces downwards towards the support base 13 of the laser device 1 that supports the substrate 21. In other words, the worker positions the substrate 21 such that the first surface 21a of the substrate 21 faces upwards towards the laser irradiation surface.

[0034] Next, the operator operates the laser device 1 to emit the first laser 2a from the first laser light source 2 toward the first axicon lens 4.

[0035] The first laser 2a, via the first beam expander 3, is refracted radially from the optical axis by the first axicon lens 4, forming a Bessel beam in the space immediately behind the first axicon lens 4.

[0036] The first laser 2a emitted from the first axicon lens 4 travels through the first lens 5 towards the mirror 6. The first laser 2a is reflected by the mirror 6 and travels towards the beam splitter 7. The first laser 2a is reflected by the beam splitter 7 and passes through the objective lens 8. The first laser 2a then irradiates the first surface 21a of the substrate 21.

[0037] The wavelength of the first laser 2a is, for example, within the 1-micron range. Specifically, the wavelengths of the first laser 2a are, for example, 1030 nm, 1040 nm to 1060 nm, and 1064 nm. Therefore, a ytterbium-doped solid-state laser can be used as the first laser 2a.

[0038] Furthermore, the pulse width of the first laser 2a is between 100 femtoseconds and less than 100 picoseconds. If the pulse width of the first laser 2a falls below 100 femtoseconds, the design difficulty of the laser device 1 increases, making it difficult to adopt this embodiment as a method for manufacturing the substrate 21 having micropores.

[0039] When the first laser 2a is irradiated onto the substrate 21, the irradiated area is modified to become a light-absorbing region.

[0040] Next, the second laser light source 9 emits the second laser 9a toward the second axicon lens 11.

[0041] The second laser 9a, via the second beam expander 10, is refracted radially from the optical axis by the second axicon lens 11, forming a Bessel beam in the space immediately behind the second axicon lens 11.

[0042] The second laser 9a emitted from the second axicon lens 11 travels through the second lens 12 towards the beam splitter 7. The second laser 9a passes through the beam splitter 7 and the objective lens 8. The second laser 9a then irradiates the first surface 21a of the substrate 21.

[0043] The wavelength of the second laser 9a is, for example, in the 1-micron or 2-micron range. Specifically, the wavelengths of the second laser 9a are, for example, 1030 nm, 1040 nm to 1060 nm, 1064 nm, etc. Therefore, a ytterbium-doped fiber laser can be used as the second laser 9a. The wavelengths of the first laser 2a and the second laser 9a may be the same or different.

[0044] Furthermore, the pulse width of the second laser 9a is less than 1 nanosecond to 1 millisecond. Specifically, the pulse width of the second laser 9a is, for example, 2 microseconds, 20 microseconds, etc. Furthermore, the pulse width of the second laser 9a should be in the microsecond range, not the nanosecond range, in order to apply sufficient heat to the substrate 21 and perform drilling operations on the order of 10 μm in diameter.

[0045] When the second laser 9a is irradiated onto the substrate 21, the modified areas are removed and holes are made. In this case, since the optical axes of the first laser 2a and the second laser 9a coincide, the maximum diameter of the holes that can be made in the substrate 21 is limited, and is limited to about 30 μm.

[0046] Figure 2 illustrates the timing of emission from the first laser 2a and the second laser 9a. In this figure, time t represents the emission interval between the first laser 2a and the second laser 9a. Note that time t includes 0 seconds and negative values. The timing at which the laser device 1 emits laser pulses can be determined by several examples, as shown below. First, in Figure 2, an example can be given in which the first laser light source 2 emits the first laser 2a, and then the second laser light source 9 emits the second laser 9a. In this case, it is preferable that the time t between the emission of the first laser 2a and the emission of the second laser 9a be as small as possible. After irradiation (modification) with the first laser 2a, if heat is not applied quickly, holes cannot be created by the second laser 9a. Therefore, the time t before irradiation with the second laser 9a should preferably be, for example, within 5 picoseconds.

[0047] Next, we can give an example where the first laser 2a and the second laser 9a are emitted simultaneously (in this case, time t is 0 seconds). Furthermore, an example can be given in which the first laser 2a is emitted after the second laser 9a is emitted (in this case, time t is a negative value). However, after the irradiation of the first laser 2a is completed, the irradiation time of the second laser 9a should be sufficient for it to be absorbed by the substrate 21 and impart energy, for example, between 1 nanosecond and less than 1 millisecond, and specifically preferably 20 microseconds or more.

[0048] The primary purpose of irradiation with the first laser 2a is to create a modified area within the substrate 21 where the pulse energy of the second laser 9a is efficiently absorbed. Therefore, this modification can be easily achieved by shortening the wavelength using harmonic generation technology. For example, the first laser 2a may be a laser that converts the laser output in the 1-micron wavelength band to output at a wavelength including the second and third harmonics, and the second laser 9a may be a solid-state laser that outputs in the 2-micron wavelength band. For example, a first laser 2a can be used that has been converted to 515 nm or 532 nm as the second harmonic and 355 nm or 343 nm as the third harmonic. The glass material substrate 21 is transparent at all wavelengths, but it can be modified by inducing multiphoton absorption through focused irradiation. Since multiphoton absorption is induced at lower energy densities at shorter wavelengths, using a short-wavelength laser is advantageous.

[0049] The irradiation from the first laser 2a and the second laser 9a is combined as a time-waveform modulated laser pulse, and since their optical axes coincide, this can be performed by a single laser device 1. Furthermore, when combining the first laser 2a and the second laser 9a to generate a single time-wavelength modulated laser pulse, their respective wavelengths may be different.

[0050] To synchronize the first laser 2a and the second laser 9a and align their optical axes, coupling means including polarization coupling and wavelength coupling can be used. The drilling operation can be performed, for example, by coupling a ytterbium-doped solid-state laser as the first laser 2a and a ytterbium-doped fiber laser as the second laser 9a using coupling means including polarization coupling and wavelength coupling, integrating the two laser pulses optically coaxially, and modulating the time waveform of the laser pulse (time-waveform modulated laser pulse).

[0051] Alternatively, the same time-waveform modulated laser pulse obtained by combining the first laser 2a and the second laser 9a can be realized using semiconductor lasers, semiconductor optical amplifiers (SOAs), and interferometric optical modulators. For example, a long pulse can be generated by generating a gain-switch spike followed by a long-duration current injection, and this time-waveform modulated laser pulse can be amplified by a single linear optical amplifier while maintaining the time waveform. In this way, a laser with a time waveform and pulse energy equivalent to the pulse obtained by combining the first laser 2a and the second laser 9a can be created.

[0052] In the manufacturing method of the substrate having micropores according to the embodiment described above, one or more micropores are formed, and a time-wavelength modulated laser pulse consisting of a first laser 2a and a second laser 9a is irradiated once per micropore.

[0053] Next, the worker performs chemical etching on the perforated substrate 21. Chemical etching enlarges the diameter of the holes in the substrate 21. For chemical etching to be performed, it is necessary that the diameter of the holes drilled by the first laser 2a and the second laser 9a is greater than or equal to a certain diameter. In other words, in order to perform chemical etching to obtain via holes of a certain diameter, a pore size is required that allows the chemical etching solution to flow smoothly into the substrate 21. A pore size that does not become blocked by laser processing debris or foreign dust is, for example, in the range of 1 μm to 30 μm, and preferably in the range of 10 μm to 20 μm.

[0054] When the substrate 21 is glass, the chemical etching solution is a solution mainly composed of either hydrofluoric acid (HF) or potassium hydroxide. Specifically, a solution mainly composed of hydrofluoric acid (HF) is, for example, a hydrofluoric acid-nitric acid mixture obtained by adding an appropriate amount of nitric acid to hydrofluoric acid.

[0055] By performing chemical etching, the pore size of the substrate 21 can be expanded to approximately 50 μm. Furthermore, when performing drilling work by irradiating with the second laser 9a, molten material adheres to the surface of the substrate 21, but chemical etching can also remove this molten material.

[0056] Furthermore, the pore size of the substrate 21 can be adjusted by adjusting the chemical etching process time. For example, shortening the chemical etching process time will result in a pore size smaller than 50 μm, while lengthening the chemical etching process time will result in a pore size larger than 50 μm.

[0057] Figures 3 and 4 are cross-sectional views showing the pore shape of the substrate 21 after chemical etching. Figure 5 is a graph showing the relationship between pore size and chemical etching time. Figure 3 shows the conventional technique, which involves irradiating the substrate 21 with an ultrashort pulse laser, followed by chemical etching and drilling. As shown in this figure, the shape of the pores is drum-shaped. Therefore, the pore diameter in region a near the surface of the substrate 21 is larger than the pore diameter in region b in the center of the substrate 21.

[0058] In this conventional technique, the modified portion of the substrate 21 is gradually dissolved by chemical etching, starting from the first surface 21a and the second surface 21b and moving towards the center of the substrate 21. As a result, the pores become drum-shaped.

[0059] Figure 4 shows the shape of the pores in the substrate 21 manufactured according to this embodiment, where the pores are opened almost perpendicularly (straight) from the first surface 21a to the second surface 21b. Therefore, the pore diameter in region A near the surface of the substrate 21 is equivalent to the pore diameter in region B in the center of the substrate 21.

[0060] In the manufacturing method of the substrate 21 having micropores according to this embodiment, holes are made in the substrate 21 by the first laser 2a and the second laser 9a before chemical etching, so that the chemical etching solution enters the holes uniformly from immediately after the start of chemical etching. Therefore, chemical etching can be performed on the entire interior of the holes early on. As a result, the holes become almost vertical.

[0061] Figure 5 is a graph showing the relationship between pore size and chemical etching treatment time for the conventional method and the method for manufacturing a substrate 21 having micropores according to this embodiment. In the graph shown in Figure 5, the vertical axis represents pore size (μm), the horizontal axis represents time (h), the dotted line a represents the pore size of region a in Figure 3, the dotted line b represents the pore size of region b in Figure 3, the solid line A represents the pore size of region A in Figure 4, and the solid line B, which overlaps with solid line A, represents the pore size of region B in Figure 4.

[0062] As shown by the dotted lines a and b in Figure 5, when the substrate 21 is modified using conventional technology, if the substrate 21 has no pores, or if the pores in the substrate 21 are less than, for example, 1 μm in diameter, the time required for chemical etching will be approximately 8 hours or more. In this case, in the conventional technique, when chemical etching is performed, the substrate 21 is gradually dissolved from the first surface 21a and the second surface 21b toward the center of the substrate 21. Therefore, the time required to enlarge the pore size in region b is longer than the time required to enlarge the pore size in region a.

[0063] This is because, if the substrate 21 does not have holes, or if the substrate 21 has holes but the hole diameter is, for example, less than 1 μm, the chemical etching solution will not enter the holes immediately after the start of chemical etching, or even if the chemical etching solution does enter the holes, only a small amount will enter.

[0064] As shown by the solid lines A and B in Figure 5, when holes are made in the substrate 21 using the manufacturing method of the substrate 21 having micropores of this embodiment, the pore diameter is about 20 μm (1 μm to 30 μm) in both region A and region B. As a result, the chemical etching solution flows into the pores quickly, and the time required for chemical etching is about 1 hour. Thus, the method for manufacturing the substrate 21 having micropores according to this embodiment makes it possible to shorten the time required for chemical etching.

[0065] As described above, the method for manufacturing the substrate 21 having micropores according to this embodiment allows for the creation of large-diameter holes in a shorter time compared to the conventional technique.

[0066] (Second embodiment) Next, a second embodiment of this disclosure will be described with reference to Figures 6, 7, and 8. In the method for manufacturing a substrate having micropores described in this embodiment, the method for creating a time-wavelength modulated laser pulse differs from that of the first embodiment described above, and this time-wavelength modulated laser pulse is created by a single laser generating means 22.

[0067] As shown in Figure 6, the manufacturing method for this substrate having micropores involves modulating an ultrashort pulse generated by an ultrashort pulse current source 24 with a long pulse generated by a long pulse current source 25 in the seeder 23 of the laser generating means 22. The output is passed through an LD26 (laser diode) to generate laser light, and the output is amplified by a preamplifier 27 and a power amplifier 28 to create a time-waveform modulated laser pulse.

[0068] In this case, the output waveform of LD26 is shown in Figure 7(a), and the output waveform of power amplifier 28 is shown in Figure 7(b). As shown in these figures, the output of LD26 is emitted as a seed pulse having a high peak power ultrashort pulse portion (gain switch spike portion) and a low power long pulse portion (long pulse tail portion). The seed pulse has an output energy of, for example, the order of 1 nJ in total. It is then amplified by the preamplifier 27 to, for example, the order of 100 nJ, and by the power amplifier 28 to, for example, the order of 100 μJ.

[0069] The pulse width of the ultrashort pulse section is, for example, about 10 picoseconds, and the pulse width of the long pulse section is, for example, about 2 microseconds. The pulse energy of the ultrashort pulse portion is, for example, about 10 μJ, and the pulse energy of the long pulse portion is, for example, about 100 μJ.

[0070] Figure 8 shows the overall configuration of the laser device 1, in which the time-wavelength modulated laser pulse generated by the laser generating means 22 is emitted towards the axicon lens 30 via the beam expander 29. The beam expander 29 is used to expand or contract the diameter of the time-wavelength modulated laser pulse.

[0071] The axicon lens 30 is a cone-shaped lens. Alternatively, a Diffractive Optical Element (DOE) or a spatial phase modulator can be used as a substitute optical element with equivalent functionality to the axicon lens 30. The axicon lens 30 focuses the laser beam toward the optical axis, thereby forming a Bessel beam in the space immediately behind the axicon lens 30.

[0072] The time-waveform modulated laser pulse emitted from the axicon lens 30 travels through lens 31 and towards the objective lens 8. The lens 31 and objective lens 8 are composed of a single-element spherical plano-convex lens, an aspherical lens, or a lens in which multiple lenses are combined and fixed. The time-wavelength modulated laser pulse then passes through the objective lens 8 and is irradiated onto the first surface 21a of the substrate 21 as a single laser.

[0073] In this second embodiment, as in the first embodiment, holes are drilled in the substrate 21, and then the hole diameter is enlarged by chemical etching. In this second embodiment, the same effects and advantages as those of the first embodiment described above can be obtained.

[0074] (Third embodiment) Next, a third embodiment of this disclosure will be described with reference to Figures 9 and 10. In this embodiment, a time-wavelength modulated laser pulse is generated by wavelength conversion using a nonlinear optical crystal (a time-wavelength modulated laser pulse is obtained in which the ultrashort pulse portion has a shorter wavelength by harmonic generation using a nonlinear optical crystal). That is, as shown in Figure 9, for example, a pulse having a pulse width of 1064 nm is wavelength-converted to a pulse of 532 nm to obtain a time-wavelength modulated laser pulse having an ultrashort pulse portion and a long pulse portion.

[0075] Figure 10 shows the relationship between fundamental wave intensity and harmonic intensity. For example, in the case of the second harmonic (SHG), the conversion efficiency is approximately 50% in terms of energy ratio. The steps after obtaining the time-waveform modulated laser pulse are the same as those in the first and second embodiments described above. In this embodiment as well, the same effects and advantages as those of the first and second embodiments described above can be obtained.

[0076] Although methods for manufacturing the substrate 21 having micropores in these embodiments have been described, these are merely illustrative examples and do not limit the scope of the technology relating to this disclosure in any way. Any method for manufacturing a substrate having micropores is acceptable, provided it is a TGV formation technology that includes perforating the substrate with a time-wavelength modulated laser pulse and performing chemical etching with a through-via diameter of 1 μm or more. It can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the technology relating to this disclosure. [Explanation of Symbols]

[0077] 1. Laser device 2. First laser light source 2a First laser 3. First beam expander 4. First Axicon Lens 5. The first lens 6 Mirror 7 Beam Splitter 8 Objective lenses 9. Second laser light source 9a Second laser 10. Second beam expander 11. Second Axicon Lens 12. The second lens 13 Support stand 21 Base material 21a First surface 21b Second surface 22 Laser generating means 23 Cedar 24. Ultrashort pulse current source 25 Long pulse current source 26 LD 27 Preamplifier 28 Power Amplifier 29 Beam Expander 30 Axicon Lens 31 lenses

Claims

1. TGV formation technology, Perforating a substrate using a time-waveform modulated laser pulse, A method for producing a substrate having fine pores, comprising performing chemical etching with a pore diameter of 1 μm or more for through vias created by the aforementioned perforation.

2. The method for manufacturing a substrate according to claim 1, wherein the drilling is performed on the substrate using a time-waveform modulated laser pulse obtained by combining a first laser consisting of an ultrashort pulse laser and a second laser consisting of a long pulse laser.

3. The method for producing a substrate according to claim 1, wherein the pore diameter is in the range of 1 μm to 30 μm.

4. The method for manufacturing a substrate according to claim 2, wherein the pulse width of the first laser is 100 femtoseconds to less than 100 picoseconds, and the pulse width of the second laser is 1 nanosecond to less than 1 millisecond.

5. The method for manufacturing a substrate according to claim 2, wherein the wavelengths of the first laser and the second laser are in the range of 1 micron.

6. The method for manufacturing a substrate according to claim 2, wherein the substrate is irradiated with the first laser and then with the second laser.

7. The method for manufacturing a substrate according to claim 6, wherein the second laser is irradiated within 5 picoseconds after the first laser is irradiated.

8. The method for manufacturing a substrate according to claim 2, wherein the first laser is irradiated after the second laser has been irradiated.

9. The method for manufacturing a substrate according to claim 2, wherein the perforation is performed by coupling a ytterbium-doped solid-state laser as the first laser and a ytterbium-doped fiber laser as the second laser using coupling means including polarization coupling and wavelength coupling, integrating the two laser pulses optically coaxially, and performing the perforation with the time-wavelength modulated laser pulse.

10. The first laser is a laser that converts the laser output in the 1-micron wavelength band and outputs at any wavelength including the second harmonic and the third harmonic. The method for manufacturing a substrate according to claim 2, wherein the second laser is a solid-state laser that outputs in the wavelength band of 1 micron or 2 microns.

11. A method for manufacturing a substrate having micropores, wherein one or more micropores are formed, The method for manufacturing a substrate according to claim 2, wherein the time-wavelength modulated laser pulse, comprising the first laser and the second laser, is irradiated once per microhole.

12. The method for producing a substrate according to claim 1, wherein the chemical etching is carried out using a solution mainly composed of a chemical substance including hydrofluoric acid or potassium hydroxide.

13. A method for manufacturing a substrate according to claim 1, wherein the drilling is performed with a single laser that emits a time-waveform modulated laser pulse having an ultrashort pulse portion having high peak power and a long pulse portion having low power.

14. A method for manufacturing a substrate according to claim 1, wherein the drilling is performed with a time-wavelength modulated laser pulse in which the ultrashort pulse portion has been shortened in wavelength by harmonic generation using a nonlinear optical crystal.

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