Method for manufacturing a substrate having pores

Abstract

To provide a method of adequately forming a hole with a desired shape.SOLUTION: A manufacturing method includes steps of: preparing a base material having a first surface and a second surface which face each other; forming a light absorptive area extending along a drawing axis from the first surface of the base material by irradiating the first surface of the base material with a first laser having a transparent wavelength to the base material, the first laser having a pulse width of 100 ns or less; and selectively removing the base material in the light absorptive area by irradiating the light absorptive area with a second laser having a transparent wavelength to the base material at least during a time overlapping with an irradiation time of the first laser, the second laser having a pulse width of 1 micro second or more, and made incident on the first surface of the base material at an incident angle of 5-50° inclusive to the drawing axis of the light absorptive area.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to a method for manufacturing a substrate having holes.

Background Art

[0002] Conventionally, a method of forming holes such as through-holes in a workpiece using a short-pulse laser has attracted attention.

[0003] Particularly in recent years, a technique has been proposed in which a short-pulse laser as a first laser and a CW laser or a long-pulse laser as a second laser are combined to form fine holes in a workpiece (for example, Patent Document 1).

[0004] In such a method (hereinafter referred to as the "double laser method"), after irradiating a workpiece with a first laser to form a high-strain region (hereinafter also referred to as a "light absorption region") from the surface of the workpiece toward the inside, by irradiating the light absorption region with a second laser coaxial with the first laser, the material in the light absorption region is removed. As a result, fine holes can be formed at positions corresponding to the light absorption regions of the workpiece.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the "double laser method", it is possible to form fine holes that are difficult to form using a single laser. <​​

[0008] This invention has been made in view of the above background, and aims to provide a method for manufacturing a substrate having holes using a "double laser method" that can appropriately form holes of a desired shape. [Means for solving the problem]

[0009] The present invention provides a method for manufacturing a substrate having pores, (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 the stretch axis, wherein the first laser has a pulse width of 100 nanoseconds or less. (3) A step of selectively removing the substrate in the light-absorbing region by irradiating the light-absorbing region with a second laser having a wavelength transparent to the substrate for at least a time overlapping with the irradiation time of the first laser, 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 manufacturing method having the above characteristics is provided. [Effects of the Invention]

[0010] The present invention provides a method for manufacturing a substrate having holes using a "double laser method," which enables the appropriate formation of holes of a desired shape. [Brief explanation of the drawing]

[0011] [Figure 1] This figure schematically shows an example of a flow chart for a method of manufacturing a substrate according to one embodiment of the present invention. [Figure 2] This figure schematically shows an example of the configuration of an apparatus for carrying out a method for manufacturing a substrate according to one embodiment of the present invention. [Modes for carrying out the invention]

[0012] The following describes one embodiment of the present invention.

[0013] As mentioned above, when holes are formed in a substrate using a conventional "double laser method," such as the method described in Patent Document 1, it has been observed that holes with shapes different from the desired shape are often formed. For example, in the formed holes, the diameter of the opening on the laser irradiation side may expand unintentionally, or the shape of the tip of the hole may deviate from the stretching axis.

[0014] The following are possible causes for this problem.

[0015] In the "double laser method," irradiation with the first laser creates a high-temperature light-absorbing region inside the substrate. This light-absorbing region has a temporarily increased light absorption rate compared to other parts of the substrate due to thermionic excitation and / or band gap reduction. Therefore, although the second laser is normally transparent to the substrate, irradiating this light-absorbing region with the second laser causes the second laser to be absorbed by the light-absorbing region. As a result, the material contained in the light-absorbing region melts and sublimes, allowing the material to be removed from the light-absorbing region.

[0016] Here, the second laser is irradiated coaxially with the first laser. That is, the second laser is irradiated from the same side of the substrate irradiation surface (referred to as the "laser irradiation surface") as the first laser, but the second laser is absorbed in the light-absorbing region near this laser irradiation surface. In that case, it becomes difficult for the second laser to propagate sufficiently across the entire depth range of the light-absorbing region.

[0017] Also, the first laser is usually a short-pulse laser with a pulse width of about 10 picoseconds at maximum. Therefore, even if a photoabsorptive region is formed inside the base material by irradiation with the first laser, its existence time does not last long. In particular, as described above, when the second laser is absorbed at the upper part of the photoabsorptive region and its further progress is hindered, the temperature of the photoabsorptive region decreases before the second laser reaches the entire photoabsorptive region. As a result, when the second laser reaches, a situation may occur where the photoabsorptive region has already lost its photoabsorbing property.

[0018] In this way, in the conventional method, most of the second laser is absorbed by the laser-irradiated surface, and as a result, it becomes difficult to effectively irradiate the photoabsorptive region inside the base material with the second laser within the time the photoabsorptive region persists. Therefore, it is considered that a hole with a desired shape cannot be appropriately formed.

[0019] Under such considerations, the inventors of the present application have intensively studied to improve the reproducibility of the shape of the hole formed by the "double laser method". Then, the inventors of the present application have found that a hole with a desired shape can be appropriately formed by making the second laser incident at an incident angle of 5° or more with respect to the extension axis of the photoabsorptive region.

[0020] Therefore, in one embodiment of the present invention, A method for manufacturing a base material having a hole, <​​​​(3) During at least a time overlapping with the irradiation time of the first laser, the light-absorbing region is irradiated with a second laser having a wavelength transparent to the base material, to selectively remove the base material 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 base material at an incident angle of 5° or more and 50° or less with respect to the extension axis of the light-absorbing region. A manufacturing method is provided.

[0021] In the present application, the "incident angle" of the laser means the angle α (where 0° < α < 90°) of the irradiation direction of the laser with respect to the extension axis of the light-absorbing region.

[0022] In one embodiment of the present invention, as the second laser, a light beam incident at an incident angle of 5° or more with respect to the extension axis of the light-absorbing region is used.

[0023] In this case, the second laser can be efficiently irradiated over the entire light-absorbing region generated in the base material by the irradiation of the first laser. Therefore, in one embodiment of the present invention, unlike the conventional case, most of the second laser is absorbed near the surface of the base material irradiated with the first laser (i.e., the "laser irradiation surface"), and it is difficult to sufficiently irradiate the second laser over the depth direction of the light-absorbing region. This problem can be significantly suppressed.

[0024] Also, in the conventional "double laser method", the energy of the second laser tends to concentrate on the side of the laser irradiation surface of the base material. Therefore, the diameter of the processed hole may become larger than necessary, or cracks may occur in the processed hole.

[0025] On the other hand, in the method according to one embodiment of the present invention, the energy of the second laser is not concentrated on the laser irradiation surface, but is distributed over the entire light-absorbing region. Therefore, in the method according to one embodiment of the present invention, the problem that the diameter of the opening on the laser irradiation side of the formed hole spreads unintentionally or cracks occur around the hole can also be significantly reduced.

[0026] Furthermore, in the method according to one embodiment of the present invention, the second laser can be efficiently irradiated onto the light-absorbing region within the substrate during the time that the light-absorbing region persists. Therefore, in the method according to one embodiment of the present invention, the problem of the shape of the tip of the formed hole being deviated from the stretching axis can be significantly reduced or prevented.

[0027] Due to these effects, the method according to one embodiment of the present invention can appropriately form holes of desired dimensions and shapes in the substrate.

[0028] In conventional "double laser methods," the material is gradually removed from the laser-irradiated surface inward. Therefore, to form a hole of sufficient depth, it is necessary to repeat the irradiation of the first and second lasers. As a result, considerable processing time is required, for example, when forming a through-hole in a thick substrate.

[0029] In contrast, in one embodiment of the present invention, the entire light-absorbing region can be efficiently irradiated with a second laser while the high-temperature light-absorbing region is maintained. Therefore, in one embodiment of the present invention, it is possible to significantly shorten the processing time.

[0030] In the method according to one embodiment of the present invention, the upper limit of the incident angle of the second laser is 50° or less. This is because if the incident angle of the second laser exceeds 50°, the effect of the second laser being reflected by the first surface can no longer be ignored.

[0031] The second laser may be, for example, a Bessel beam at the position where it irradiates the substrate. If the second laser is a Bessel beam, such a Bessel beam may have a conical half-angle of 5° or more and 50° or less.

[0032] Here, the "conical half-angle" of the Bessel beam refers to the angle θ (where 0 < θ < 90°) between the (height) axis and the generatrix of a right circular cone, where the base is the region enclosed by the outer diameter of the beam immediately after it exits the objective lens 140, and the apex is the centroid of the region where the hole is to be formed.

[0033] For example, the second laser may be a Bessel beam having a conical half-angle of 6° or more and 40° or less.

[0034] Furthermore, if the second laser is a Bessel beam, the second laser is typically incident on the first surface such that the axis of the aforementioned right cone coincides with the extension axis of the light-absorbing region. Therefore, in this case, the "angle of incidence" of the laser is considered to be the "half-angle of the cone" of the Bessel beam. (Method for manufacturing a substrate according to one embodiment of the present invention) The following describes one embodiment of the present invention in more detail with reference to the drawings.

[0035] Figure 1 shows an example of a flow chart of a method for manufacturing a substrate according to one embodiment of the present invention (hereinafter referred to as the "first method").

[0036] As shown in Figure 1, the first method is: (1) A step of preparing a substrate having a first surface and a second surface facing each other (step S110), (2) A step (step S120) in which the first surface of the substrate is irradiated with a first laser having a wavelength transparent to the substrate, thereby forming a light-absorbing region extending from the first surface of the substrate along the stretch axis, wherein the first laser has a pulse width of 100 nanoseconds or less, (3) A step (step S130) in which the light-absorbing region is irradiated with a second laser having a wavelength transparent to the substrate for at least a time overlapping with the irradiation time of the first laser, and the substrate in the light-absorbing region is selectively removed, 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, It holds.

[0037] Figure 2 shows an example of the configuration of an apparatus for carrying out the first method.

[0038] As shown in Figure 2, the apparatus 100 includes a first laser light source 110 and a second laser light source 120, a first axicon lens 114 and a second axicon lens 124, a first lens 116 and a second lens 126, a mirror 130, a beam splitter 134, an objective lens 140, and a support base 150.

[0039] The objective lens referred to here is the lens positioned closest to the substrate being illuminated, and includes single-element spherical or plano-convex lenses, aspherical lenses, cemented lenses, and lenses made up of multiple lenses fixed to the lens barrel.

[0040] Using this device 100, one or more holes are formed in the substrate 160.

[0041] The first laser light source 110 has the role of emitting the first laser 112 toward the first axicon lens 114. The first axicon lens 114 has the role of refracting the angle of the laser beam radially from the optical axis center to form a Bessel beam in the space immediately behind the first axicon lens 114. The Bessel beam formed here is then reduced and projected to a desired magnification by the subsequent first lens 116 and objective lens 140 and irradiated onto the substrate 160. The first laser 112 emitted from the first axicon lens 114 travels toward the first lens 116 and mirror 130. The mirror 130 guides the first laser 112 toward the beam splitter 134.

[0042] The first axicon lens 114 can also be replaced by a diffractive optical element such as a reflective axicon element, an aspherical refractive lens, a diffractive optical element (DOE), or a spatial light modulator, as these are alternative optical elements capable of forming a similar function.

[0043] Meanwhile, the second laser light source 120 has the role of emitting the second laser 122 toward the second axicon lens 124. The second axicon lens 124 has the role of refracting the angle of the laser beam radially from the optical axis center to form a Bessel beam. The Bessel beam formed here is then reduced and projected to the desired magnification by the second lens 126 and objective lens 140 and irradiated onto the substrate 160. The second laser 122 emitted from the second axicon lens 124 is then guided to the beam splitter 134 via the second lens 126.

[0044] The beam splitter 134 has the function of reflecting the first laser 112 and transmitting the second laser 122. Alternatively, the beam splitter 134 may have the function of reflecting the second laser 122 and transmitting the first laser 112, in which case the arrangement of the first laser 112 and the second laser 122 may be swapped.

[0045] Furthermore, the beam splitter 134 is preferably a polarization-separating or wavelength-separating beam splitter. A non-polarizing half-mirror type beam splitter can also be used, but this results in greater energy loss, so in this case, the output of the laser light source must be increased.

[0046] Furthermore, as shown in Figure 2, it is preferable that the first laser 112 and the second laser 122 irradiate the substrate 160 via the beam splitter 134 and the objective lens 140 in that order. In this case, it becomes possible to align the irradiation positions of the first laser and the second laser with high precision.

[0047] The first laser 112 and the second laser 122 pass through the beam splitter 134 and then the objective lens 140 before irradiating the first surface 162 of the substrate 160.

[0048] The support base 150 has the function of holding the base material 160.

[0049] The following describes each step in the first method with reference to the apparatus 100 in Figure 2.

[0050] (Step S110) First, the substrate 160 to be processed is prepared. The material of the substrate 160 is not particularly limited, as long as it is transparent to the wavelengths of the first laser 112 and the second laser 122.

[0051] The substrate 160 may be, for example, glass or sapphire. Alternatively, the substrate 160 may be a compound semiconductor such as silicon, SiC, or GaN. Furthermore, the substrate 160 may be composed of a resin such as polyimide, polycarbonate, fluororesin, polyethylene, acrylic, PEEK (polyetheretherketone), epoxy resin, urethane resin, or vinyl chloride resin. Alternatively, the substrate 160 may be any other brittle material.

[0052] The dimensions and shape of the base material 160 are not particularly limited. However, if through holes are formed in the base material 160, the thickness of the base material 160 is preferably 1 mm or less.

[0053] The base material 160 has a first surface 162 and a second surface 164 that are opposite to each other.

[0054] Next, the substrate 160 is placed on the support base 150. The substrate 160 is positioned on the support base 150 such that the second surface 164 faces the support base 150, that is, the first surface 162 becomes the laser irradiation surface.

[0055] Furthermore, the sides and back of the substrate 160 can also be fixed. For example, if the laser is positioned parallel to the floor in the direction of travel, the support base 150 may be placed on the back side of the substrate perpendicular to the main surface.

[0056] (Process S120) Next, the first laser 112 is irradiated from the first laser light source 110 toward the first axicon lens 114.

[0057] The first laser 112 is refracted radially from the optical axis by the first axicon lens 114, and a Bessel beam is formed in the space immediately behind the first axicon lens 114.

[0058] Next, the first laser 112 emitted from the first axicon lens 114 travels through the first lens 116 towards the mirror 130. The first laser 112 is reflected by the mirror 130 and guided to the beam splitter 134. Subsequently, the first laser 112 is reflected by the beam splitter 134, passes through the objective lens 140, and is projected onto the first surface 162 of the substrate 160 in a reduced Bessel beam of a desired magnification by the first lens 116 and the objective lens 140.

[0059] The first laser 112 has a wavelength that is "transparent" to the substrate 160. In this application, a transparent wavelength means a laser wavelength at which the absorption coefficient of the substrate 160 is 10 / cm or less.

[0060] The wavelength of the first laser 112 is, for example, in the range of 300 nm to 3000 nm. The wavelength of the first laser 112 may also be, for example, 1064 nm, 1030 nm, 780 nm, 532 nm, 515 nm, 390 nm, 355 nm, 343 nm, 266 nm, or 257 nm.

[0061] The first laser 112 is a short-pulse laser capable of generating sufficient multiphoton absorption in the substrate 160. The pulse width of the first laser 112 is preferably in the range of more than 0.1 picoseconds and 1 nanosecond or less, and more preferably more than 1 picosecond.

[0062] Furthermore, the pulse energy of the first laser 112 is, for example, 1 μJ / shot or more in order to form a high-temperature light-absorbing region. Preferably, the pulse energy of the first laser 112 is 10 μJ / shot or more, and more preferably 100 μJ / shot or more.

[0063] The first laser 112 may be a Gaussian beam or a Bessel beam at the position where it irradiates the substrate. When the first laser 112 is a Bessel beam, the depth of focus is improved, so that a longer light-absorbing region can be formed from the first surface 162 to the second surface 164 of the substrate 160.

[0064] If the first laser 112 is a Bessel beam, the first laser 112 may have a conical half-angle of 5° or more and 50° or less.

[0065] The first laser 112 may be irradiated onto the first surface 162 of the substrate 160 to form a spot in the range of, for example, 1 μm to 50 μm.

[0066] Irradiation with the first laser 112 generates a high-temperature region on the substrate 160, extending from the first surface 162 toward the second surface, where a light-absorbing region is formed. The light-absorbing region extends along the stretch axis from the first surface 162 toward the second surface 164.

[0067] (Step S130) Next, a second laser 122 is irradiated from the second laser light source 120 toward the second axicon lens 124.

[0068] The second laser 122 is refracted radially from the optical axis by the second axicon lens 124, and a Bessel beam is formed in the space immediately behind the second axicon lens 114.

[0069] The second laser 122 emitted from the second axicon lens 124 is guided to the beam splitter 134 via the second lens 126. The second laser 122 then passes through the beam splitter 134 and irradiates the first surface 162 of the substrate 160 via the objective lens 140.

[0070] The second laser 122 also has a wavelength that is "transparent" to the substrate 160.

[0071] The wavelength of the second laser 122 is, for example, in the range of 300 nm to 3000 nm.

[0072] The second laser 122 is a long-pulse laser (including a continuous-wave laser). The pulse width of the second laser 122 is 1 microsecond or more. Preferably, the pulse width of the second laser 122 is in the range of 1 to 1000 microseconds.

[0073] The maximum output power of the second laser 122 is, for example, in the range of 10W to 10,000W. The maximum output power of the second laser 122 may also be below the ablation threshold of the substrate 160.

[0074] When the second laser 122 is irradiated onto the light-absorbing region of the substrate 160, the material in the light-absorbing region is selectively removed, and a hole is formed therein. The formed hole may be a bottomed hole or a through hole.

[0075] Furthermore, in steps S120 and S130, it is preferable that the time difference ts (=t2-t1) between the irradiation start time t1 of the first laser 112 and the irradiation start time t2 of the second laser 122 be as small as possible. This is because reducing the time difference ts makes it possible to reliably irradiate the light-absorbing region with the second laser 122 while the light-absorbing region is still present.

[0076] For example, the time difference ts may be a negative value. This means that the first laser 112 is irradiated while the substrate 160 is being irradiated with the second laser 122.

[0077] In other words, the region where a light-absorbing region is to be formed later may be kept irradiated with the second laser 122, and during this time, the first laser 112 may be irradiated in such a state that a light-absorbing region is formed in that region. This allows the second laser 122 to be irradiated more appropriately across the light-absorbing region.

[0078] The light-absorbing region formed by irradiation with the first laser 112 can only exist for a very short time. Therefore, "irradiating the light-absorbing region with the second laser for a time that overlaps with the irradiation time of the first laser" means that the second laser is irradiated while the light-absorbing region is still present. Specifically, this means that the time difference ts is zero, a negative value, or a positive value corresponding to the very short time the light-absorbing region exists. The time for which the light-absorbing region exists depends on the material of the substrate and the laser irradiation conditions, but as an example, it is less than 1 μsec.

[0079] Here, the second laser 122 is irradiated onto the substrate 160 at an incident angle of 5° or more and 50° or less with respect to the extension axis of the light-absorbing region.

[0080] For example, the second laser 122 is a Bessel beam having a conical half-angle of 5° or more and 50° or less, and this Bessel beam may be irradiated so as to cover the light-absorbing region.

[0081] In this case, the entire light-absorbing region can be irradiated with the second laser 122 in a relatively short time. That is, in the first method, the light-absorbing region can be sufficiently irradiated with the second laser 122 within the time that the light-absorbing region persists inside the substrate 160.

[0082] Therefore, the first method can significantly resolve the problem, as in the conventional method, in which most of the second laser 122 is absorbed near the laser-irradiated surface of the substrate 160, making it difficult to sufficiently irradiate the entire depth region of the light-absorbing area with the second laser 122.

[0083] Furthermore, in the first method, the second laser 122 is irradiated at an incident angle of 5° or more and 50° or less with respect to the extension axis of the light-absorbing region. This reduces problems such as the energy of the second laser 122 concentrating on the laser irradiation surface, causing the opening of the processed hole to become unacceptably large, or cracks to occur near the opening of the processed hole.

[0084] Furthermore, the first method also mitigates the problem of increased processing time due to the absorption of most of the second laser 122 at the laser irradiation surface.

[0085] Due to the effects described above, the first method makes it possible to properly form holes of the desired dimensions and shape in the base material 160. Furthermore, the first method makes it possible to significantly reduce the time required for hole processing.

[0086] In this first method, the diameter of the formed hole can be controlled by adjusting the irradiation conditions of the second laser 122, particularly the irradiation time and irradiation power of the second laser 122.

[0087] For example, the diameter of the pores may be adjusted to a range of 0.5 μm to 30 μm.

[0088] Furthermore, if necessary, the above process may be repeated to form multiple holes in the substrate 160. In such cases, it is preferable that the spacing between adjacent holes be 20 μm or more. By spacing adjacent holes to 20 μm or more, the possibility of previously formed holes interfering with the processing of subsequent holes can be significantly suppressed.

[0089] The above describes a method for manufacturing a porous substrate according to one embodiment of the present invention, using the first method utilizing the apparatus 100 shown in Figure 2 as an example.

[0090] However, it will be obvious to those skilled in the art that the method according to the present invention is not limited to the method described above.

[0091] For example, in the apparatus shown in Figure 2, the base material 160 is placed on the support base 150.

[0092] However, alternatively, a movable base may be used instead of the support base 150.

[0093] Such a movable platform has the function of moving horizontally, for example, in the left-right direction in Figure 2. In this case, by moving the movable platform, the substrate 160 can be moved left-right relative to the first laser 112 and the second laser 122. Therefore, it becomes possible to continuously form multiple holes in the substrate 160.

[0094] Alternatively, the first laser 112 and the second laser 122 may be moved while the substrate 160 is fixed.

[0095] Furthermore, when holes are continuously formed in the substrate 160 using such a "moving method," it is preferable that the distance between the irradiation position of the first laser 112 on the first surface 162 of the substrate 160 and the irradiation position of the second laser 122 on the first surface 162 is less than 3 μm.

[0096] By maintaining such a distance, it becomes possible to properly form holes even in the "movement method."

[0097] In addition, various modifications can be made to the first method and apparatus 100. [Examples]

[0098] Examples of the present invention will be described below. In the following description, Examples 1 to 16 are examples, and Examples 21 to 23 are comparative examples.

[0099] (Example 1) Holes were formed in the substrate using the apparatus 100 shown in Figure 2.

[0100] A quartz glass substrate with a thickness of 300 μm was used. The first and second axicon lenses of apparatus 100 had an apex angle of 178°. The focal lengths of the first and second lenses were set to 400 mm. The focal length of the objective lens was set to 30 mm.

[0101] The first laser was a short-pulse laser with a wavelength of 1030 nm. The pulse width was 6 picoseconds, and the pulse energy was 150 μJ. The first laser was also a Bessel beam, with a cone half-angle of 7.0.

[0102] The first laser was shone onto the substrate, which was placed with its first surface facing upward, such that the axis of the first laser was at a 90° angle to the substrate. The incident beam diameter was 7 mm.

[0103] The second laser was a long-pulse laser with a wavelength of 1070 nm. The pulse width was 10 microseconds, and the maximum output power was 200 W. The second laser was a Bessel beam, and the cone half-angle was set to 7.0.

[0104] The incident beam diameter of the second laser was set to 7 mm, and the second laser was irradiated onto the first surface of the substrate so that the axis of the second laser was at a 90° angle to the substrate.

[0105] The first laser was applied once during the irradiation of the second laser.

[0106] This process was repeated multiple times, changing the location on the substrate, to form multiple through-holes in the substrate. The pitch between adjacent holes was set to 50 μm.

[0107] (Examples 2-4) Pores were formed in the substrate using the same method as in Example 1.

[0108] However, in Examples 2 to 4, the pulse width of the first laser was changed to form multiple through-holes in the substrate. The conditions for the second laser were the same as in Example 1.

[0109] (Examples 5-15) Pores were formed in the substrate using the same method as in Example 1.

[0110] However, in Examples 5 to 15, the conditions of the first and second lasers were changed to form a single through-hole in the substrate.

[0111] (Example 16) Pores were formed in the substrate using the same method as in Example 1.

[0112] However, in this Example 16, the conditions for the first and second lasers were changed from those in Example 1. Also, in Example 16, the substrate was moved while the first and second lasers were irradiated onto the substrate to continuously form through holes. The substrate's moving speed was set to 30 mm / sec.

[0113] The pitch between adjacent pores was set to 30 μm.

[0114] (Examples 21-23) Pores were formed in the substrate using the same method as in Example 1.

[0115] However, in Examples 21 to 23, the conditions of the first and second lasers were changed to form a single hole in the substrate. In particular, both the first and second lasers were Gaussian beams, and Bessel beams were not used. Also, in Examples 21 to 22, alkali-free glass was used as the substrate.

[0116] Tables 1 to 3 below show the process conditions used in each example. In particular, Table 1 summarizes the conditions for the first laser used in each example. Table 2 summarizes the conditions for the second laser used in each example. Furthermore, Table 3 summarizes the other conditions used in each example.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3] (evaluation) The following evaluations were performed using the processed substrates obtained in each example.

[0120] (Hole machining condition) The state of pores was observed in each substrate.

[0121] Observations revealed that through-holes were formed in the substrates of Examples 1 to 16. In these substrates, the shape of the longitudinal cross-section of the through-holes was approximately a straight line parallel to the extension axis, confirming that the desired shape of the through-holes was obtained.

[0122] Furthermore, no significant widening of the diameter was observed at the opening of the through-hole, and no abnormalities such as cracks were found near the through-hole.

[0123] In contrast, it was found that non-through holes were formed in Examples 21 to 23. Furthermore, in the substrates of Examples 21 to 23, the shape of the longitudinal cross-section of the holes was tapered, and an abnormal increase in dimensions was observed on the opening side.

[0124] (Measuring the diameter of the hole) Using the through holes formed in the substrates in Examples 1 to 16, the diameter of the opening on the laser irradiation side and the diameter of the opening on the laser emission side were measured.

[0125] The measurement results showed that various values ​​were obtained for the diameter of the through-holes in Examples 1 to 16. For example, in Examples 5 to 7, the diameter of the holes changed despite the irradiation conditions of the first laser being the same.

[0126] This indicates that even if the irradiation conditions of the first laser remain constant, the diameter of the hole can be controlled by adjusting the irradiation conditions of the second laser.

[0127] Furthermore, it was found that there was no significant difference between the diameter of the aperture on the laser irradiation side and the diameter of the aperture on the emission side, indicating that a straight through-hole could be achieved.

[0128] Table 4 below summarizes the evaluation results obtained for each example.

[0129] [Table 4] In the evaluation column, "○" indicates that no abnormalities were found in the shape of the hole, while "×" indicates that shape abnormalities such as non-axisymmetrical properties and / or increased diameter of the opening were found in the processed hole. Furthermore, "-" indicates that no hole was formed.

[0130] The present invention has the following aspects. (Aspect 1) A method for manufacturing a substrate having pores, (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 the stretch axis, wherein the first laser has a pulse width of 100 nanoseconds or less. (3) A step of selectively removing the substrate in the light-absorbing region by irradiating the light-absorbing region with a second laser having a wavelength transparent to the substrate for at least a time overlapping with the irradiation time of the first laser, 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 manufacturing method having the following characteristics. (Aspect 2) The manufacturing method according to embodiment 1, wherein the first laser has a pulse width of more than 0.1 picoseconds or more than 1 picosecond. (Aspect 3) The manufacturing method according to embodiment 1 or 2, wherein the second laser is a Bessel beam. (Aspect 4) The manufacturing method according to any one of embodiments 1 to 3, wherein the first laser is a Bessel beam having a conical half-angle of 5° or more. (Aspect 5) The manufacturing method according to any one of embodiments 1 to 4, wherein the first laser and the second laser are irradiated onto the substrate via a beam splitter and an objective lens in that order. (Aspect 6) The manufacturing method according to embodiment 5, wherein the beam splitter is a polarization-separating or wavelength-separating beam splitter. (Aspect 7) By this manufacturing method, one or more holes are formed in the substrate. The manufacturing method according to any one of embodiments 1 to 6, wherein the diameter of the hole is controlled by the irradiation conditions of the second laser. (Pattern 8) The manufacturing method according to embodiment 7, wherein the diameter is in the range of 0.5 μm to 30 μm. (Aspect 9) The manufacturing method according to embodiment 7, wherein the hole is a through hole. (Aspect 10) The manufacturing method according to embodiment 7, wherein the spacing between adjacent holes is 20 μm or more. (Aspect 11) The manufacturing method according to any one of embodiments 1 to 10, wherein steps (2) and (3) are performed on the substrate moving with respect to the first laser and the second laser. (Aspect 12) The manufacturing method according to any one of embodiments 1 to 11, wherein the distance between the irradiation position of the first surface of the first laser and the irradiation position of the first surface of the second laser is less than 3 μm. (Aspect 13) The manufacturing method according to any one of embodiments 1 to 12, wherein the substrate has a thickness of 1 mm or less. [Explanation of Symbols]

[0131] 100 devices 110 First laser light source 112 First Laser 114 First Axicon Lens 116 First Lens 120 Second laser light source 122 Second laser 124 Second Axicon Lens 126 The second lens 130 Mirror 134 Beam Splitter 140 objective lens 150 Support stand 160 Base material 162 First surface 164 Second surface

Claims

1. A method for manufacturing a substrate having pores, (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 the stretch axis, wherein the first laser has a pulse width of 100 nanoseconds or less. (3) A step of selectively removing the substrate in the light-absorbing region by irradiating the light-absorbing region with a second laser having a wavelength transparent to the substrate for at least a time overlapping with the irradiation time of the first laser, 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 manufacturing method having the following characteristics.

2. The manufacturing method according to claim 1, wherein the first laser has a pulse width of more than 0.1 picoseconds or more than 1 picosecond.

3. The manufacturing method according to claim 1, wherein the second laser is a Bessel beam.

4. The manufacturing method according to claim 1 or 2, wherein the first laser is a Bessel beam having a conical half-angle of 5° or more.

5. The manufacturing method according to claim 1 or 2, wherein the first laser and the second laser are irradiated onto the substrate via a beam splitter and an objective lens in that order.

6. The manufacturing method according to claim 5, wherein the beam splitter is a polarization-separating or wavelength-separating beam splitter.

7. By this manufacturing method, one or more holes are formed in the substrate. The manufacturing method according to claim 1 or 2, wherein the diameter of the hole is controlled by the irradiation conditions of the second laser.

8. The manufacturing method according to claim 7, wherein the diameter is in the range of 0.5 μm to 30 μm.

9. The manufacturing method according to claim 7, wherein the hole is a through hole.

10. The manufacturing method according to claim 7, wherein the spacing between adjacent holes is 20 μm or more.

11. The manufacturing method according to claim 1 or 2, wherein steps (2) and (3) are performed on the substrate moving relative to the first laser and the second laser.

12. The manufacturing method according to claim 1 or 2, wherein the distance between the irradiation position of the first surface of the first laser and the irradiation position of the first surface of the second laser is less than 3 μm.

13. The manufacturing method according to claim 1 or 2, wherein the substrate has a thickness of 1 mm or less.

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