Ablation processing method, ablation processing device, and substrate

Abstract

The present invention is an ablation processing method for forming a processed recessed-part on a surface of a substrate by ablation processing by irradiation energy of a laser beam, in which the ablation processing is performed such that an angle formed between a side wall surface of the processed recessed-part on an opening side of the processed recessed-part and a surface of the substrate is 80° or more and 90° or less. As a result, it is possible to provide a substrate used for a high-performance semiconductor package substrate capable of achieving high density and low resistance of wiring resistance.

Description

Ablation processing method, ablation processing device and substrate

[0001] The present invention relates to an ablation processing method, an ablation processing apparatus, and a substrate.

[0002] Semiconductor package substrates have been actively developed in line with the trend of "More Than Moore" to SoC (System on a Chip), which integrates a system into a single chip. Furthermore, the configuration of semiconductor package substrates is becoming more complex and denser.

[0003] Regarding the formation of a circuit pattern on a printed wiring board, for example, Patent Document 1 describes a method for manufacturing a printed wiring board, which includes curing a relief printing plate while pressing it against the surface of an uncured resin layer on a substrate, peeling the relief printing plate from the cured resin layer on the substrate to form grooves on the surface of the resin layer, and filling the grooves with a conductive paste to form conductive wiring.

[0004] Furthermore, Patent Document 2 describes that vias for forming via wiring, which are holes for forming via wiring, are formed by a photolithography process.

[0005] JP 2004-253432 A JP 2020-087981 A

[0006] The configuration of semiconductor package substrates is becoming increasingly complex and denser, and further increases in density are desired. At the same time, there is also a demand for lower wiring resistance in metal wiring formed by filling through holes, recesses, etc., formed in semiconductor package substrates with metal. However, high-resolution patterns result in high wiring resistance, and to prevent this, processing that achieves a deep processing depth and a wide width all the way to the bottom is required. The recess formation methods described in Patent Documents 1 and 2 have low recess formation accuracy, and are insufficient in terms of increasing density and reducing wiring resistance, making it difficult to expect improved performance.

[0007] The present invention has been made to solve the above problems, and aims to provide a substrate used for a semiconductor package substrate that allows for high density and low wiring resistance, as well as a high-performance ablation processing method and ablation processing device that can process recesses in such a substrate.

[0008] The present invention has been made to achieve the above-mentioned object, and provides an ablation processing method for forming a processed recess on the surface of a substrate by ablation processing using the irradiation energy of a laser beam, in which the ablation processing is performed so that the angle between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

[0009] Such an ablation processing method enables high-precision processing, and can provide a substrate for use in a semiconductor package substrate that allows for high density and low wiring resistance.

[0010] At this time, the energy density of the laser beam irradiated to the processed portion of the substrate is set to 1.0 [J / cm ２ ] or more.

[0011] This makes it possible to provide a substrate that can be used for a high-performance semiconductor package substrate, which allows for higher density and lower wiring resistance more easily and stably.

[0012] At this time, the irradiation size of the laser beam can be reduced by passing the laser beam through a reduction projection optical lens having an NA of 0.12 or more.

[0013] This allows for more precise processing, and makes it easier to achieve higher density and lower wiring resistance, thereby providing a substrate that can be used for a high-performance semiconductor package substrate.

[0014] At this time, the irradiation size of the laser beam is adjusted by passing the laser beam through a mask, and by performing a sweeping operation by fixing the laser beam and synchronizing the mask and the substrate stage on which the substrate is placed, the laser beam is swept relative to the pattern area of ​​the mask, and ablation processing of a size larger than the irradiation size of the laser beam is performed to form the processed recess.

[0015] This makes it possible to provide a substrate that can be used for a high-performance semiconductor package substrate, which allows for higher density and lower wiring resistance more easily and stably.

[0016] The present invention has also been made to achieve the above-mentioned object, and provides an ablation processing apparatus that forms a processed recess on the surface of a substrate by ablation processing using the irradiation energy of a laser beam, the ablation processing apparatus including a first optical function unit equipped with a laser light source that irradiates the laser beam, a substrate stage on which the substrate is placed, and a control unit that controls the ablation processing apparatus, wherein the control unit controls the ablation processing so that the angle between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

[0017] Such an ablation processing apparatus allows high-precision processing, and can manufacture substrates for use in semiconductor package substrates that allow for high density and low wiring resistance.

[0018] At this time, the control unit sets the energy density of the laser beam irradiated to the processing portion of the substrate to 1.0 [J / cm ２ ] or more.

[0019] This makes it possible to provide a substrate that can be used for a high-performance semiconductor package substrate, which allows for higher density and lower wiring resistance more easily and stably.

[0020] In this case, the projection system may further include a reduction projection optical lens having an NA of 0.12 or more, and the irradiation size of the laser beam may be reduced by passing the laser beam through the reduction projection optical lens.

[0021] This allows for more precise processing, and makes it easier to achieve higher density and lower wiring resistance, making it possible to provide a substrate that can be used for a high-performance semiconductor package substrate.

[0022] In this case, the device may further include a mask that adjusts the beam shape of the laser beam by passing the laser beam through it, and the control unit may hold the laser beam at a fixed position and perform a sweeping operation in synchronization with the mask and the substrate stage, thereby sweeping the laser beam relative to the pattern area of ​​the mask and performing ablation processing of a size larger than the irradiation size of the laser beam to form the processed recess.

[0023] This makes it possible to provide a substrate that can be used for a high-performance semiconductor package substrate, which allows for higher density and lower wiring resistance more easily and stably.

[0024] The present invention has also been made to achieve the above-mentioned object, and provides a substrate used for a semiconductor package substrate, which has at least one recess on its surface, and the angle between the side wall surface of the recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

[0025] Such a substrate allows for high density and low wiring resistance, making it suitable for use in high performance semiconductor packages.

[0026] As described above, the ablation processing method of the present invention enables high-precision processing and is an ablation processing method that can manufacture substrates used for semiconductor package substrates that allow for high density and low wiring resistance.

[0027] Furthermore, the ablation processing apparatus of the present invention is capable of high-precision processing, and can manufacture substrates used for semiconductor package substrates that allow for high density and low wiring resistance.

[0028] The substrate of the present invention allows for high density and low wiring resistance, and can be used as a substrate for a high-performance semiconductor package substrate.

[0029] Fig. 3 is a cross-sectional schematic diagram showing an example of a substrate used in the semiconductor package substrate of the present invention. Fig. 4 is a schematic diagram showing an example of an ablation processing apparatus of the present invention. Fig. 5 is a schematic diagram showing an example of laser irradiation in the ablation processing method of the present invention. Fig. 6 is a schematic diagram showing out-focus of the laser irradiation in Fig. 3. Fig. 7 is a schematic diagram showing an example of the ablation processing method of the present invention. Fig. 8 is a schematic diagram showing another example of laser irradiation in the ablation processing method of the present invention. Fig. 9 is a cross-sectional schematic diagram showing an example of a processed recess that can be formed by the ablation processing method of the present invention. Fig. 10 is an intensity distribution of an example of a laser that can be used in the ablation processing method of the present invention.

[0030] As described above, there has been a demand for a substrate to be used in a high-performance semiconductor package that allows for high density and low wiring resistance, as well as an ablation processing method and an ablation processing apparatus that can process recesses in such a substrate.

[0031] As a result of extensive research into the above-mentioned problems, the inventors discovered that high-precision processing is possible by performing ablation processing using the irradiation energy of a laser beam, and that it is possible to obtain a substrate having a processed recess in which the angle between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less, and thus completed the present invention.

[0032] In other words, the present invention is an ablation processing method for forming a processed recess on the surface of a substrate by ablation processing using the irradiation energy of a laser beam, and the ablation processing is performed so that the angle between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

[0033] The present invention also provides an ablation processing apparatus that forms a processed recess on the surface of a substrate by ablation processing using the irradiation energy of a laser beam, and includes a first optical function unit equipped with a laser light source that irradiates the laser beam, a substrate stage on which the substrate is placed, and a control unit that controls the ablation processing apparatus, wherein the control unit controls the ablation processing so that the angle between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

[0034] The present invention also relates to a substrate used for a semiconductor package substrate, which has at least one recess on the surface of the substrate, and the angle formed between the side wall surface of the recess on the opening side of the recess and the surface of the substrate is 80° or more and 90° or less.

[0035] The present invention will be described in detail below, but the present invention is not limited thereto. In this specification, the terms "recess" and "machined recess" include not only recesses having a bottom surface but also so-called through holes having no bottom surface.

[0036] [Substrate] FIG. 1 is a schematic diagram showing an example of a substrate used in the semiconductor package substrate of the present invention. The substrate 70 used in the semiconductor package substrate shown in FIG. 1 has at least one recess 200 on its surface. The angle (θ) between the sidewall surface 200S of the recess 200 on the opening side and the surface 70S of the substrate is 80° or more and 90° or less. In another aspect, the angle (θ) between the opening edge 200T of the recess 200, which is parallel to the surface 70S of the substrate 70, and the sidewall surface 200S of the recess, is 80° or more and 90° or less. Such a substrate 70 can achieve both high density and low resistance of the metal wiring, thereby achieving high performance. The lower limit of the angle (θ) can be preferably 83° or more, more preferably 85° or more.

[0037] There are no particular limitations on the material of the substrate 70. The substrate 70 may be a substrate or laminate containing at least one of ceramic, resin, semiconductor, metal, and the like.

[0038] The substrate of the present invention allows for high density and low wiring resistance, and can be used as a substrate for a high-performance semiconductor package substrate.

[0039] [Ablation Processing Apparatus] The ablation processing apparatus according to the present invention is capable of manufacturing a substrate used in the semiconductor package substrate of the present invention described above. Figure 2 is a schematic diagram showing an example of the ablation processing apparatus according to the present invention. The ablation processing apparatus 100 shown in Figure 2 is an apparatus that forms a processed recess (including a through hole) in a substrate 70 using a laser. Note that the ablation processing apparatus 100 shown in Figure 2 is an example of the ablation processing apparatus according to the present invention, and the ablation processing apparatus according to the present invention is not limited to the apparatus shown in Figure 2.

[0040] The ablation processing apparatus 100 according to the present invention includes a first optical function unit 20 equipped with a laser light source 10 that irradiates a laser beam 1, a substrate stage 60 on which a substrate 70 is placed, and a control unit 80 that controls the ablation processing apparatus 100. The control unit 80 controls the ablation processing so that the angle formed between the side wall surface of the processing recess on the opening side of the processing recess and the surface of the substrate is 80° or more and 90° or less.

[0041] The ablation processing apparatus according to the present invention, equipped with such a control unit 80, is capable of forming high-density processed recesses such as vias and trenches in processing semiconductor package substrates, etc., and is also capable of performing recess formation processing with a high aspect ratio, so it is possible to form deep processed recesses such as vias and trenches. As a result, it is possible to achieve high density and reduce the resistance value of the metal wiring embedded in the processed recesses, resulting in an ablation processing apparatus that can manufacture high-performance semiconductor package substrates.

[0042] The structure, material, etc. of the substrate stage 60 are not particularly limited as long as it can hold the substrate 70 .

[0043] The first optical function unit 20 includes a laser light source 10 that emits a laser beam 1. The laser light source 10 may be, for example, a laser light source (laser oscillator) 10 that emits (emits) the laser beam 1 in a pulsed manner. More specifically, the laser light source 10 may include an excimer laser oscillator. By using an excimer laser, it is possible to efficiently process a workpiece made of an organic material, such as an ABF substrate, and achieve highly productive processing. Furthermore, because excimer lasers have low coherence, the use of an excimer laser makes it possible to achieve extremely uniform beam formation.

[0044] Furthermore, excimer lasers allow for more precise adjustment of the processing depth and the width of recesses and / or through holes than solid-state lasers. Excimer lasers are particularly useful for forming recesses such as fastening holes and trenches. Therefore, by using excimer lasers, it is possible to precisely process complex concave and convex shapes, such as those on circuit boards.

[0045] The irradiation shape of the laser beam 1 emitted by the laser light source 1 is not particularly limited, and in addition to the shapes shown in FIGS. 2, 3, and 6, it may be an irradiation shape having an intensity distribution such that the laser intensity is greatest at the center (inside) 1a and is small at the hem (outside) 1b, for example, as shown in FIG. 8.

[0046] The first optical function unit 20 can include a prism 21 and a shaping optical system 22 in addition to the laser light source 10 that oscillates the laser beam 1. As will be described in detail below, the prism 21 is a prism that converts a laser beam having an intensity distribution in which the laser intensity is greatest at the center and smaller at the skirts into a laser beam having an irradiation shape in which the intensity of the outer portion of the intensity distribution of the laser beam is greater than the intensity of the inner portion, and the shaping optical system 22 is a shaping optical system that converts the irradiation shape of the laser converted by the prism 21 into a top-hat irradiation shape. In the example of the ablation processing apparatus 100 shown in FIG. 2 , the prism 21 includes a roof prism but may also include a conical prism.

[0047] As described above, it is preferable that the first optical function unit 20 is configured to set the irradiation shape of the laser beam 1 so that the intensity distribution of the laser on the processing surface of the substrate 70 is such that the intensity of the outer part of the intensity distribution is greater than the intensity of the inner part.

[0048] The ablation processing apparatus 100 according to the present invention may further include a mask 30, a folding mirror 40, and a reduction projection optical lens 50, in this order, in the optical path of the ablation processing apparatus 100 from the first optical function unit 20 to the substrate 70, as shown in FIG.

[0049] The reduction projection optical lens 50 reduces the irradiation size of the laser beam 1 by passing the laser beam 1. By providing such a reduction projection optical lens 50, the mask pattern formed on the mask 30 can be enlarged compared to the processing pattern to be actually formed on the workpiece.

[0050] By enlarging the mask pattern formed on the mask 30 more than the actual processing pattern, the energy of the laser beam 3 that strikes the mask 30 can be made smaller than the actual processing energy. If the reduction magnification of the reduction projection optical lens 50 is N, the laser energy that strikes the mask surface is 1 / (N ２ ) As a result, thermal drift due to the energy of the laser beam 3 can be suppressed, and therefore thermal expansion of the mask 30 can be suppressed, making it possible to perform high-precision processing even after a long processing operation.

[0051] Furthermore, deterioration of optical members (for example, the first optical function portion 20 and the mask 30) due to the heat of the laser beam can be suppressed, and the life of the optical members can be extended.

[0052] The reduction projection optical lens 50 may include a pair of reduction projection lenses. When the reduction projection optical lens 50 is an infinity optical system, the magnification achieved by the reduction projection optical lens 50 can be adjusted, for example, by adjusting the ratio of the focal lengths of the reduction projection lenses and the distance between the reduction projection lenses.

[0053] The NA of the reduction projection optical lens 50 is preferably selected in accordance with the energy density and processing resolution required for processing the substrate 70. The NA of the reduction projection optical lens 50 is preferably 0.12 or greater. By setting the NA of the reduction projection optical lens to 0.12 or greater, a laser beam with a high energy amount can be applied to the processing portion of the substrate, and processing with stable higher resolution becomes possible, thereby enabling stable processing of recesses by fine, high-aspect ablation processing. In the present invention, even when laser processing is performed with a high NA to form recesses with high resolution, it is possible to prevent the processed recesses from having a tapered shape.

[0054] In forming recesses such as fine vias and trenches in semiconductor package processing, in order to stably process the angle (θ°) between the wall surface of the recess processed by the laser beam and the plane along the surface of the substrate to a nearly perpendicular state, it is preferable to apply laser beam energy exceeding the threshold energy for ablation to the edge of the processed bottom surface. For this reason, it is preferable to increase the energy density when performing ablation processing using a laser. Therefore, the control unit 80 sets the energy density of the laser beam 1 irradiated to the processed portion of the substrate 70 to 1.0 [J / cm ２ This results in an ablation processing device that can more easily and stably provide a substrate used for a semiconductor package substrate that allows for higher density and lower wiring resistance.

[0055] Furthermore, it is preferable that the ablation processing apparatus 100 according to the present invention is equipped with the mask 30 as described above, and that the control unit 80 fixes the laser beam 1 in a fixed position and performs a sweeping operation by synchronizing the mask 30 and the substrate stage 60 on which the substrate 70 is placed, thereby sweeping the laser beam 1 relative to the pattern area of ​​the mask 30 and performing ablation processing of a size larger than the irradiation size of the laser beam 1 to form a processed recess.

[0056] By performing the sweeping operation in synchronization with the mask and substrate stage, the aperture size of the reduction projection optical lens can be made smaller. Compared to the method in which the mask and substrate stage are fixed and the laser beam is swept, there is no need to make the aperture of the reduction projection optical lens large, which prevents the lens from becoming heavy and complex, makes it easier to make the lens highly accurate, and enables the production of high-precision products.

[0057] Therefore, if the device is equipped with such a mask 30 and control unit 80, it will be an ablation processing device that can provide substrates to be used for semiconductor package substrates that can more easily achieve higher density and lower wiring resistance.

[0058] The ablation processing apparatus 100 of the present invention preferably further comprises a temperature adjusting means for adjusting the temperature of the reduction projection optical lens 50. By providing the temperature adjusting means, it is possible to effectively suppress the influence of heat caused by the laser energy on the reduction projection optical lens 50. In the reduction projection optical lens 50, the laser beam 4 that has passed through the mask 30 is reduced and projected at 1 / N, so the energy of the laser beam that passes through the lens portion at the tip of the objective is N times smaller than the energy of the laser beam irradiated on the mask 30. ２ The ablation processing method and ablation processing apparatus 100 of the present invention can use a reduction projection optical lens with a very small aperture.

[0059] In particular, as mentioned above, 1.0 mJ / cm ２When using a laser beam with such a high energy density, the temperature rise caused by the laser beam incident on the reduction projection optical lens can cause slight deviations in the irradiation position, resulting in distortion of the processed pattern.In order to control the heat incident on the reduction projection optical lens as precisely as possible, it is desirable to make the aperture diameter of the reduction projection optical lens small so that temperature control can be efficiently performed from the cooling section using a jacket around the reduction projection lens.

[0060] As described above, the temperature control means for the reduction projection optical lens does not have to be directly attached to the lens itself. It may instead be a means for cooling the jacket portion that holds the lens. While temperature control is possible around the periphery of the lens when the lens diameter is large, the temperature control effect is less widespread near the crucial central portion, making heat management difficult. Therefore, even a small amount of energy absorbed into the lens due to prolonged laser irradiation can easily cause thermal distortion. If the ablation processing apparatus 100 has a temperature control function for the reduction projection optical lens 50, reducing the lens diameter can more effectively prevent such defects. Furthermore, it is possible to prevent defects caused by laser irradiation of the reduction projection optical lens 50 and extend its lifespan.

[0061] In this way, in particular, if the control unit 80 holds the laser beam 1 at a fixed position and performs a sweeping operation by synchronizing the mask 30 and the substrate stage 60 on which the substrate 70 is placed, and further has a temperature control function for the reduction projection optical lens 50, a high-precision reduction projection optical lens 50 with an NA of 0.12 or more is used, and the laser beam 1 is 1.0 mJ / cm ２ This makes it possible to perform laser ablation processing using a laser beam with a high energy density.

[0062] The ablation processing apparatus 100 shown in FIG. 2 may also include a mask alignment camera 31 as an imaging means for reading characteristic portions of the photomask 30, and a workpiece alignment camera 61 as an imaging means for reading characteristic portions of the substrate 70. The mask alignment camera 31 may be configured to send position information of the characteristic portions of the photomask 30 to the control unit 80. The workpiece alignment camera 61 may be configured to send position information of the characteristic portions of the substrate 70 to the control unit 80. The control unit 80 may be configured to adjust the relative positions of the substrate 70 and the photomask 30 based on this position information. In another aspect, the control unit 80 may be configured to synchronously move the substrate 70 and the photomask 30 placed on the substrate stage 60.

[0063] [Ablation Processing Method] The ablation processing method of the present invention can be carried out using, for example, the ablation processing apparatus of the present invention, but can also be carried out using an apparatus other than the above-mentioned ablation processing apparatus.

[0064] An example of the ablation processing method of the present invention that can be performed using the ablation processing apparatus 100 shown in FIG. 2 will be specifically described below.

[0065] The ablation processing method of the present invention is an ablation processing method for forming a recessed portion on the surface of a substrate 70 by ablation processing using the irradiation energy of a laser beam 1. The ablation processing is performed so that the angle between the sidewall surface of the recessed portion at the opening side and the surface of the substrate 70 is 80° or more and 90° or less. According to the ablation processing method of the present invention, when processing a semiconductor package substrate or the like, it is possible to form high-density recessed portions such as vias and trenches, and since recess formation processing with a high aspect ratio can be performed, it is possible to form deep recessed portions such as vias and trenches. This enables high density and low resistance of the metal wiring embedded in the recessed portions, thereby enabling the production of high-performance semiconductor package substrates.

[0066] Furthermore, in forming recesses such as minute vias and trenches in semiconductor package processing, in order to stably process the angle between the wall surface of the recess processed by the laser beam and the plane along the surface of the substrate so as to be nearly perpendicular, it is preferable to apply laser beam energy exceeding the threshold energy for ablation to the edge of the processed bottom surface. For this reason, it is preferable to increase the energy density when performing ablation processing by laser. Therefore, the energy density of the laser beam 5 irradiated to the processed portion of the substrate 70 is set to 1.0 [J / cm ２ By doing so, it is possible to provide a substrate used for a semiconductor package substrate that can more easily achieve high density and low wiring resistance.

[0067] Furthermore, it is preferable to reduce the irradiation size of the laser beam 4 by passing the laser beam 4 through a reduction projection optical lens 50 having an NA of 0.12 or more. By setting the NA of the reduction projection optical lens to 0.12 or more, a high-energy laser beam can be applied to the processing portion of the substrate, and stable processing with higher resolution is possible, enabling stable processing with fine, high-aspect ratio recess processing by ablation processing. This makes it possible to provide a substrate used for a semiconductor package substrate that can more easily achieve high density and low wiring resistance.

[0068] Furthermore, it is preferable to adjust the irradiation size of laser beam 3 by passing laser beam 3 through mask 30, fix laser beams 5 and 6, and perform a sweeping operation by synchronizing mask 30 and substrate stage 60, thereby sweeping the laser beam relative to the pattern area of ​​the mask and performing ablation processing larger than the irradiation size of laser beams 5 and 6 to form processed recesses. Processing by laser irradiation like this is also called scanning processing. In this way, it is possible to provide a substrate used for a semiconductor package substrate that can more easily achieve high density and low wiring resistance.

[0069] As described above, in the present invention, it is also effective to use scan processing, in which processing is performed while the laser beams 5 and 6 are relatively scanned over the workpiece surface 71. By performing scan processing, laser processing can be performed with high precision even on a large-area substrate 70. Furthermore, by performing scan processing, it is possible to prevent an increase in processing time even if the number of recesses and / or through holes to be processed increases.

[0070] By performing the scanning process by synchronously moving the substrate 70 placed on the substrate stage 60 and the photomask 30, it is possible to perform the laser processing without moving the laser beams 1 to 6 themselves.

[0071] Furthermore, in this embodiment, the processing area is not limited to the area of ​​the lens, so an area (angle of view) larger than the area of ​​the lens can be processed.

[0072] This embodiment allows the reduction projection optical lens 50 required for irradiation to be made smaller, and also allows for good laser irradiation position accuracy and temperature control. Furthermore, since the reduction projection optical lens 50, which will be described below, can be made smaller, image distortion due to irradiation is also reduced.

[0073] In the ablation processing apparatus 100 shown in Figure 2, when the control unit 80 is used to move the substrate 70 and the photomask 30 placed on the substrate stage 60 in synchronization, the relative positions of the substrate 70 and the photomask 30 can be adjusted based on the position information of the characteristic parts of the mask 30 obtained by the mask alignment camera 31 and the position information of the characteristic parts of the substrate 70 obtained by the workpiece alignment camera 61.

[0074] In the ablation processing method of the present invention, it is preferable to perform processing by setting the laser intensity distribution on the processing surface of the substrate 70 to an irradiation shape in which the intensity of the outer part of the intensity distribution is greater than the intensity of the inner part. Such an ablation processing method will be described by way of example with reference to Figures 2 to 5.

[0075] First, as shown in Fig. 2, a laser beam 1 having the irradiation shape shown in Fig. 2(a) is emitted from a laser light source 10. In this example, the irradiation shape of the laser beam 1 is a laser irradiation shape in which the laser intensity at the inner portion 1a is greater than the laser intensity at the outer portion 1b, as shown in Fig. 3. In another aspect, the irradiation shape of the laser beam 1 has an intensity distribution in which the laser intensity at the center (inner portion) 1a is greatest and the laser intensity at the skirt (outer portion) 1b is smaller.

[0076] Next, the laser beam 1 is incident on the prism 21 of the first optical function unit 20. The prism 21 converts the laser beam 1 into a laser beam 2 having an irradiation shape (FIG. 2(b)) in which the intensity of the outer portion of the intensity distribution of the laser beam 1 is greater than the intensity of the inner portion. FIG. 2 shows a prism 21 made up of four (two pairs of) roof prisms as an example of the prism 21. Note that FIG. 3 shows only two roof prisms 21a and 21b, which are involved in the irradiation shape of the surface of the laser beam 1 parallel to the paper surface, as a representative. Note that the prism 21 is not limited to a roof prism, and a prism including, for example, a conical prism may also be used.

[0077] Next, the laser beam 2 emitted from the prism 21 and having the irradiation shape shown in Figures 2(b) and 3 enters the shaping optical system 22. As shown in Figure 3, the shaping optical system 22 focuses each component of the laser beam 2 toward the image-forming point F1, and shapes the irradiation shape of the laser beam 2 into a top-hat irradiation shape shown in Figure 2(c), thereby forming the laser beam 3.

[0078] The laser beam 3 is incident on the photomask 30 located at the position of the image forming point F1. The photomask 30 has a mask pattern corresponding to the pattern to be processed on the substrate 70. By scanning and irradiating the laser beam onto the substrate 70 via the photomask 30, recesses and / or through-holes can be formed in the substrate 70 in a desired pattern.

[0079] The laser beam 4 emitted from the photomask 30 and having the irradiation shape (top hat shape) shown in Fig. 2(d) is redirected by a folding mirror 40 and enters a reduction projection optical lens (projection lens) 50. The effect of using an optional reduction projection optical lens 50 will be described later.

[0080] The laser beam 5 emitted from the reduction projection optical lens 50 reaches the surface (initial processing surface) 71 of the substrate 70, as shown in Fig. 3. Fig. 3 shows an example in which the image forming point F2 of the reduction projection optical lens 50 is aligned with the surface 71 of the substrate 70. However, the image forming point F2 of the reduction projection optical lens 50 is not limited to the surface 71 of the substrate 70.

[0081] As shown in Fig. 3, the irradiation shape of the laser beam 5 irradiated onto the surface 71 of the substrate 70 is a top hat shape as shown in Fig. 2(e) and Fig. 3. On the other hand, at the surface 72 to be processed that has progressed further from the image point F2, as shown in Fig. 3, the intensity distribution of the laser beam 6 is set to an irradiation shape in which the intensity of the outer portion 6b of the intensity distribution is greater than the intensity of the inner portion 6a.

[0082] 2 and 3, as shown in outline in Figures 4(a) to 4(e), as the distance from the image forming point F2 increases (under focus U), the irradiation shape of the laser beam 6 approaches the irradiation shape of the laser beam 2 before shaping by the shaping optical system 22. This is the reason why the intensity distribution of the laser beam 6 has an outer portion 6b of the intensity distribution with a greater intensity than an inner portion 6a.

[0083] The ablation processing method of the present invention processes the workpiece surface 72 by setting the intensity distribution of the laser beam 6 to an irradiation shape in which the intensity of the outer portion 6b of the intensity distribution is greater than the intensity of the inner portion 6a, thereby more effectively and stably preventing the recess 200 from tapering, as shown schematically in FIG. 5 . By continuing the processing, a through hole can be formed with stable tapering suppression. Therefore, the angle between the sidewall surface of the processed recess at the opening side and the substrate surface can be stably maintained at 80° or more and 90° or less. Furthermore, the ablation processing method of the present invention can more effectively and stably prevent the processed recess 200 from tapering, thereby enabling the formation of high-resolution, complex patterns. Furthermore, the ablation processing method of the present invention can more effectively and stably prevent the processed recess 200 from tapering, even when the processed recess is formed with high resolution.

[0084] In the ablation processing method of the present invention, it is more preferable to process at least a part of a work surface 72 of a substrate 70 with a laser having an irradiation shape in which the intensity of an outer portion 6b is greater than the intensity of an inner portion 6a. For example, as shown in the examples of Figures 2 and 3, a surface (initial work surface) 71 of the substrate 70 may be processed with a laser beam 5 having a top-hat irradiation shape.

[0085] In the present invention, as shown in FIG. 5, for example, as the processing progresses in the depth direction of the substrate 70, the shape of the intensity distribution of the laser beam 6 on the processing surface 72 of the substrate 70 can be changed to perform processing.

[0086] From another perspective, the example of Figure 5 can also be said to be an example of processing by changing the shape of the intensity distribution of the laser beam 6 so that the intensity of the outer portion 6b in the intensity distribution of the laser beam 6 becomes greater than the intensity of the inner portion 6a as processing progresses in the depth direction of the substrate 70.

[0087] By carrying out the processing in this manner, it is possible to more reliably prevent the processed recesses to be formed from having a tapered shape, and in turn to more reliably form highly precise and complex patterns.

[0088] In addition, when processing is performed by setting the intensity distribution of the laser beam 6 on at least one workpiece surface 72 of the substrate 70 to an irradiation shape in which the intensity of the outer portion 6a of the intensity distribution is greater than the intensity of the inner portion 6b, there is no need to continuously change the laser intensity distribution.

[0089] In the present invention, a mask 30 can also be used to form a predetermined pattern of recesses. Even when the mask 30 is used, the intensity distribution of the laser beam 6 on the processing surface 72 of the substrate 70 can be shaped so that the intensity of the outer portion 6b of the intensity distribution is greater than the intensity of the inner portion 6a. This effectively prevents the recesses (including through holes) from tapering, thereby enabling the formation of highly precise and complex patterns. Alternatively, as shown in FIG. 5, the present invention does not require the use of the mask 30.

[0090] In another aspect, the example described with reference to Figures 2 to 5 can also be said to be an ablation processing method for forming a processed recess in a substrate 70 using a laser beam, and an ablation processing method using a first optical function unit 20 that shapes the irradiation shape of the laser beam 2, in which the intensity of the outer part is greater than the intensity of the inner part in the intensity distribution of the laser beam, into a top-hat irradiation shape.

[0091] By laser processing the substrate 70 using the first optical function unit 20 as described above, at least a portion of the substrate 70 away from the surface can be processed with an irradiation shape of the laser beam 6 in which the intensity of the outer portion 6b is greater than the intensity of the inner portion 6a. With this ablation processing method, even when processing recesses with high resolution, the width of the bottom of the recess can be more reliably and stably prevented from being smaller than the width of the opening of the recess on the initial processing surface 71. Furthermore, with this ablation processing method, even when forming through holes with high resolution, the width of the lower opening of the through hole can be more reliably and stably prevented from being smaller than the width of the upper end of the through hole. In other words, with the ablation processing method of the present invention as expressed in this aspect, even when processing recesses with high resolution, the processed recesses can be more reliably and stably prevented from having a tapered shape, thereby enabling the formation of high-resolution, complex patterns.

[0092] The substrate 70 that is the object of laser processing in the present invention is not particularly limited, but may be, for example, a semiconductor package substrate.

[0093] In particular, when processing semiconductor package substrates, there are processing patterns in which the processing recesses, for example, VIA processing and groove processing, are mixed. In this case, the method of the present invention allows processing in the same process without separating the VIA processing and groove processing steps. Furthermore, as semiconductor package substrates become increasingly dense, the laser drill method for VIA processing increases the processing time due to the increased number of holes drilled as a result of higher density, but this method does not increase the processing time due to the increased number of holes drilled or the higher resolution of the pattern.

[0094] As described above, the present invention makes it possible to form a highly precise pattern of recesses. Specifically, the present invention makes it possible to form recesses having a width of, for example, 20 μm or less and in which tapering is suppressed.

[0095] The recess formed by the present invention may have a depth of, for example, 20 μm or less. If the processing depth is smaller than the thickness of the substrate 70, a recess with a bottom can be formed, and if the processing depth is the same as the thickness of the substrate 70, a through hole can be formed.

[0096] In another aspect, the present invention allows for the formation of a pattern of recesses with a high aspect ratio. For example, recesses can be formed in which the ratio of the height of the recess to the width of the bottom of the recess is 1.0 or more. Furthermore, the present invention allows for the formation of recesses in which the ratio of the height of the recess to the width of the lower opening of a through hole is 1.0 or more.

[0097] In yet another aspect, according to the present invention, it is possible to form, for example, a recess whose bottom width is 70% or more of the opening width of the recess on the initial processing surface of the workpiece, and / or a through hole whose lower opening width is 70% or more of the width of the upper opening width of the through hole on the initial processing surface of the workpiece.

[0098] Furthermore, in the present invention, since the recesses can be formed while suppressing tapering, it is also possible to form a plurality of recesses 200 and set the distance 202 between the bottoms of adjacent recesses 200 to 110% or less of the width 201 of the bottoms, as shown in Fig. 7. Therefore, in the present invention, a plurality of recesses 200 can be formed at high density.

[0099] As described above, the ablation processing method of the present invention can form a highly precise and complex pattern. Therefore, the substrate manufacturing method of the present invention, which includes the ablation processing method of the present invention, can manufacture a substrate having a highly precise and complex pattern.

[0100] This specification includes the following aspects: [1] An ablation processing method for forming a processed recess on a surface of a substrate by ablation processing using irradiation energy of a laser beam, wherein the ablation processing is performed so that the angle formed between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less. [2] The energy density of the laser beam irradiated to the processed portion of the substrate is 1.0 [J / cm ２ [3] The ablation processing method according to [1], wherein the irradiation size of the laser beam is reduced by passing the laser beam through a reduction projection optical lens having an NA of 0.12 or more. [4] The ablation processing method according to any one of [1] to [3], wherein the irradiation size of the laser beam is adjusted by passing the laser beam through a mask, the laser beam is fixed at a position, and a sweeping operation is performed in synchronization with the mask and a substrate stage on which the substrate is placed, thereby sweeping the laser beam relative to a pattern area of ​​the mask and performing ablation processing of a size larger than the irradiation size of the laser beam to form the processed recess. [5] An ablation processing apparatus for forming a processed recess on a surface of a substrate by ablation processing using irradiation energy of a laser beam, comprising: a first optical function unit having a laser light source for irradiating the laser beam, a substrate stage for placing the substrate, and a control unit for controlling the ablation processing apparatus, wherein the control unit controls the ablation processing so that the angle formed between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less. [6] The control unit controls the energy density of the laser beam irradiated to the processed portion of the substrate to 1.0 [J / cm ２[7] The ablation processing apparatus according to [5], further including a reduction projection optical lens having an NA of 0.12 or more, and reducing the irradiation size of the laser beam by passing the laser beam through the reduction projection optical lens. [8] The ablation processing apparatus according to any one of [5] to [7], further including a mask that adjusts the beam shape of the laser beam by passing the laser beam through the reduction projection optical lens, and the control unit sweeps the laser beam relative to a pattern area of ​​the mask by keeping the laser beam at a fixed position and synchronizing the mask and the substrate stage to perform a sweeping operation, thereby performing ablation processing of a size larger than the irradiation size of the laser beam and forming the processed recess. [9] A substrate used for a semiconductor package substrate, having at least one recess on a surface of the substrate, and an angle between a sidewall surface of the recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

[0101] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An ablation processing method for forming a recessed portion on the surface of a substrate by ablation processing using the irradiation energy of a laser beam, wherein the ablation processing is performed so that the angle between the side wall surface of the recessed portion on the opening side and the surface of the substrate is 80° or more and 90° or less.

2. The energy density of the laser beam irradiated to the processed portion of the substrate is set to 1.0 [J / cm ２ 2. The ablation processing method according to claim 1, wherein:

3. The ablation processing method according to claim 1, wherein the irradiation size of the laser beam is reduced by passing the laser beam through a reduction projection optical lens having an NA of 0.12 or more.

4. An ablation processing method according to any one of claims 1 to 3, wherein the irradiation size of the laser beam is adjusted by passing the laser beam through a mask, the laser beam is fixed in position, and a sweeping operation is performed in synchronization with the mask and a substrate stage on which the substrate is placed, thereby sweeping the laser beam relative to the pattern area of the mask and performing ablation processing of a size larger than the irradiation size of the laser beam to form the processed recess.

5. An ablation processing device that forms a processed recess on the surface of a substrate by ablation processing using the irradiation energy of a laser beam, comprising: a first optical function unit equipped with a laser light source that irradiates the laser beam; a substrate stage on which the substrate is placed; and a control unit that controls the ablation processing device, wherein the control unit controls the ablation processing so that the angle between the side wall surface of the processed recess on the opening side and the surface of the substrate is 80° or more and 90° or less.

6. The control unit controls the energy density of the laser beam irradiated to the processing portion of the substrate to 1.0 [J / cm ２ 6. The ablation processing device according to claim 5, wherein the ablation processing device has at least one of the following characteristics.

7. The ablation processing device according to claim 5, further comprising a reduction projection optical lens having an NA of 0.12 or more, and the irradiation size of the laser beam is reduced by passing the laser beam through the reduction projection optical lens.

8. An ablation processing apparatus according to any one of claims 5 to 7, further comprising a mask that adjusts the beam shape of the laser beam by passing the laser beam through it, wherein the control unit holds the laser beam in a fixed position and performs a sweeping operation in synchronization with the mask and the substrate stage, thereby sweeping the laser beam relative to the pattern area of the mask and performing ablation processing of a size larger than the irradiation size of the laser beam to form the processed recess.

9. A substrate used for a semiconductor package substrate, having at least one recess on the surface of the substrate, wherein the angle formed between the side wall surface of the recess on the opening side of the recess and the surface of the substrate is 80° or more and 90° or less.

Images