Laser processing method, method for manufacturing semiconductor package substrate, and laser processing device

Abstract

The present invention is a laser processing method for forming, using a laser beam, a recess in a workpiece that includes an insulating layer and a wiring layer, the laser processing method comprising: a first processing step for engraving the insulating layer of the workpiece through use of a first laser beam to form a recess, and performing processing so as to expose a portion of the wiring layer on the bottom surface of the recess; and a second processing step for removing, through use of a second laser beam, smear that is a processing residue from the first processing step and / or a portion of the insulating layer remaining on the bottom surface of the recess, the second processing step being carried out after the first processing step. This makes it possible to obtain a processed substrate having a recess in which smear on the bottom surface is sufficiently removed.

Description

Laser processing method, semiconductor package substrate manufacturing method, and laser processing device

[0001] The present invention relates to a laser processing method, a method for manufacturing a semiconductor package substrate, and a laser processing apparatus.

[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.

[0003] Furthermore, the configuration of semiconductor package substrates is becoming more complex and denser, and devices using excimer lasers are being used to manufacture the base substrates.

[0004] As semiconductor package substrates become increasingly dense, the wiring on the substrates is also required to be highly precise, and the wiring is becoming multi-layered. This high-precision and multi-layered wiring has resulted in narrower and more complex line and space (L&S). As the wiring width narrows, the wiring resistance tends to increase.

[0005] In order to connect multiple layers of wiring, through holes (VIAs) are provided, and in order to solve the problem of increased wiring resistance, trenches are provided in the substrate during the manufacture of semiconductor package substrates, and wiring is formed along these trenches. By forming such wiring, the cross-sectional area of ​​the wiring can be increased, thereby suppressing the increase in wiring resistance.

[0006] Furthermore, the manufacturing method of the semiconductor package substrate generally includes a step of forming conductive wiring to a redistribution layer (RDL) that serves to connect the semiconductor chip and the external wiring. Typically, the conductive wiring to the redistribution layer is formed by, for example, drilling a small hole by VIA processing, filling the hole with plating, and forming a through-hole conductive wiring to the redistribution layer exposed at the bottom of the hole.

[0007] During this micro-drilling process, "part of the insulating layer" or "processing residue" may remain on the bottom of the via processing area. This is generally called smear (organic residue). The presence of this smear can make it difficult for the plating to adhere to the surface of the hole during the subsequent plating process, resulting in poor deposition, or even if the plating does adhere, it may not be fully connected to the rewiring layer that was originally present on the bottom of the via. These issues can cause problems such as poor electrical connection or high connection resistance even if the connection is made.

[0008] As a means for solving such problems, for example, Patent Document 1 describes an inspection device that irradiates a resin portion or a grooved portion of a printed wiring board after processing with a laser beam to inspect for the presence or absence of a remaining resin portion. One embodiment of the inspection device includes a reprocessing system that includes a reprocessing laser oscillator and is configured to irradiate a laser beam onto the remaining resin portion (unremoved material) to re-remove the unremoved material. Note that Patent Document 1 also describes that the same laser oscillator can be used as both the inspection laser oscillator and the reprocessing laser oscillator.

[0009] Non-Patent Document 1 describes a photodesmearing process in which a buildup substrate is placed in a process chamber and irradiated with vacuum ultraviolet light from an excimer lamp in a lamp house placed above the process chamber, thereby removing smears from via holes in the buildup substrate.

[0010] International Publication No. WO2000 / 09993

[0011] Akira Aiba, Tomoyuki Hanyu, Shinichi Endo, "Applicability of Photodesmear to Via Holes in Build-up Substrates," [online], October 2016, Ushio Inc., [Retrieved March 5, 2024], Internet <URL: https: / / www.ushio.co.jp / jp / technology / lightedge / 201708 / 500229.html>

[0012] The technology of Patent Document 1 is a technology for inspecting and reprocessing a printed wiring board after processing has been completed. The technology of Non-Patent Document 1 is also a technology for performing a smear removal process, a so-called desmear process, on a build-up board, i.e., a board after processing has been completed.

[0013] However, none of these techniques removes smears at the processing stage.

[0014] The present invention has been made to solve the above problems, and aims to provide a laser processing method capable of obtaining a processed substrate having a recessed portion from which smear has been sufficiently removed from the bottom surface, a method for manufacturing a semiconductor package substrate capable of manufacturing a semiconductor package substrate having sufficiently reduced electrical resistance, and a laser processing apparatus capable of obtaining a processed substrate having a recessed portion from which smear has been sufficiently removed from the bottom surface.

[0015] In order to solve the above problems, the present invention provides a laser processing method for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, the laser processing method including: a first processing step in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess so as to expose a part of the wiring layer at the bottom of the recess; and a second processing step in which, after the first processing step, a second laser beam is used to remove a part of the insulating layer and / or smear, which is a processing residue from the first processing step, remaining at the bottom of the recess.

[0016] With the laser processing method of the present invention, a processed substrate having a recess from which smear has been sufficiently removed can be obtained by performing a second processing step of removing a part of the insulating layer and / or processing residue, i.e., smear, after the first processing step of performing the engraving process. Because such a processed substrate can be obtained by the laser processing method, there is no need to re-remove smear based on inspection results or to perform desmearing at the build-up substrate stage.

[0017] In the first processing step, it is preferable that the portion of the wiring layer be exposed over an area that is 90% or more of the area of ​​the bottom surface of the recess to be formed.

[0018] In the first processing stage, it is preferable to process the wiring layer so that the ratio of the area of ​​the exposed portion to the area of ​​the bottom surface of the recess to be formed is large; specifically, it is preferable to expose a portion of the wiring layer over an area of ​​90% or more of the area of ​​the bottom surface of the recess to be formed.

[0019] It is preferable that the first processing step exposes the portion of the wiring layer at the bottom of the recess.

[0020] In the first processing stage, it is preferable to perform processing so that a part of the wiring layer is exposed at the bottom of the formed recess.

[0021] Alternatively, in the first processing step, processing can be carried out so that a thin insulating layer is present on the bottom surface of the formed recess.

[0022] It is preferable that the first processing step and the second processing step are carried out successively using the same laser oscillator.

[0023] By continuously performing the first processing stage and the second processing stage using the same laser oscillator, it is possible to efficiently form a recess without smearing on the bottom surface without having to perform a process such as a changeover. A manufacturing method for a semiconductor package substrate incorporating such a preferred embodiment of the laser processing method can efficiently produce a high-quality semiconductor package substrate with good wiring conductivity.

[0024] For example, the insulating layer can be processed to include organic and inorganic fillers.

[0025] The laser processing method of the present invention can also process an insulating layer containing an inorganic filler.

[0026] In the second processing step, it is preferable to use a pulsed excimer laser beam as the second laser beam.

[0027] By using an excimer laser with a short wavelength, organic substances contained in a part of the insulating layer and / or processing residues can be easily decomposed, and smears can be removed efficiently.

[0028] It is preferable that the energy density of the second laser beam used in the second processing step is greater than the energy density of the first laser beam used in the first processing step.

[0029] In the second processing stage, by making the energy density of the second laser beam larger than the energy density of the first laser beam in the first processing stage, it is possible to efficiently decompose organic components contained in part of the insulating layer and / or processing residue, and to efficiently expel smear on the bottom surface to the outside of the recess.

[0030] For example, the second laser beam used in the second processing step may be a laser beam emitted from a laser oscillator and projected by a projection lens at a reduced size.

[0031] In the second processing step, it is preferable to use a very high energy density to decompose organic matter contained in part of the insulating layer and processing residue, especially at the bottom of the recess. To obtain a laser beam with such a high energy density at the recess, a high energy density is also applied to the pattern mask. However, if a second laser beam projected using a reduced projection lens is used as the second laser beam in the second processing step, the second processing can be performed with a high energy density second laser beam while minimizing the impact on the pattern mask.

[0032] The energy density of the second laser beam used in the second processing step is 1.0 J / cm ２ It is preferable to set the energy density to be equal to or higher than this.

[0033] In the second processing stage, the energy density is 1.0 J / cm ２ By using the second laser beam, the smear remaining on the bottom surface of the recess formed in the first processing step can be removed more reliably.

[0034] In the second processing step, it is preferable to irradiate the pulsed excimer laser beam five or more times.

[0035] In the second processing stage, the removal of smears on the bottom surface of the recess can be promoted by irradiating the surface with a pulsed excimer laser beam five or more times.

[0036] In the second processing step, the second laser beam is preferably incident at an angle with respect to the depth direction of the recess formed in the first processing step.

[0037] According to this preferred embodiment of the laser processing method, in the second processing step, a laser beam with a high energy density can be irradiated also near the outer periphery of the bottom surface of the recess formed in the first processing step, which results in smooth removal of smear from the entire bottom surface of the recess formed in the first processing step, thereby enabling the production of a high-quality semiconductor package substrate with good electrical conductivity.

[0038] In the second processing stage, it is preferable to irradiate the bottom surface of the recess with the pulsed excimer laser beam multiple times by performing scan irradiation so that a portion of the irradiation area with one pulsed excimer laser beam overlaps a portion of the irradiation area with another pulsed excimer laser beam.

[0039] According to the laser processing method of this preferred embodiment, in the second processing stage, smear can be removed without gaps from the entire bottom surface of the recess formed in the first processing stage.

[0040] In this case, it is more preferable to use, for example, an optical system including an oscillator that oscillates the second laser beam, a stage that holds the workpiece, and a pattern mask that has a pattern corresponding to the recess to be formed, and to perform the scanning irradiation by moving the stage and the pattern mask in synchronization while fixing the position of the optical system.

[0041] In the laser processing method according to this more preferred embodiment, in the second processing stage, smear can be removed more completely from the entire bottom surface of the recess formed in the first processing stage.

[0042] The present invention also provides a method for manufacturing a semiconductor package substrate, the method including: forming a recess in a semiconductor package substrate precursor as the workpiece by the laser processing method according to the present invention; and providing wiring to a wiring layer that is partially exposed through the formed recess.

[0043] In the method for manufacturing a semiconductor package substrate of the present invention, a recess is formed in a semiconductor package substrate precursor by the laser processing method of the present invention, so that a processed substrate having a recess from which smear on the bottom surface has been sufficiently removed can be obtained, and as a result, a high-quality semiconductor package substrate with good wiring conductivity, etc. can be efficiently produced.

[0044] The present invention also provides a laser processing apparatus for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, the laser processing apparatus comprising: an oscillator for emitting a laser beam; and a control device for controlling the laser processing apparatus to perform: a first processing stage in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess, and processing is performed so that a part of the wiring layer is exposed at the bottom of the recess; and a second processing stage in which a second laser beam is used after the first processing stage to remove a part of the insulating layer and / or smear, which is a processing residue from the first processing stage, remaining at the bottom of the recess.

[0045] With such a laser processing apparatus of the present invention, a processed substrate having a recess from which smear has been sufficiently removed can be obtained by performing a second processing step of removing processing residue, i.e., smear, after a first processing step of performing engraving. Because such a processed substrate can be obtained with a laser processing apparatus, there is no need to re-remove processing residue based on inspection or to perform desmearing at the build-up substrate stage.

[0046] As described above, the laser processing method of the present invention makes it possible to obtain a processed substrate having a recess from the bottom surface of which smears have been sufficiently removed.

[0047] Furthermore, the method for manufacturing a semiconductor package substrate of the present invention makes it possible to efficiently manufacture a high-quality semiconductor package substrate with good wiring conductivity.

[0048] Furthermore, with the laser processing apparatus of the present invention, it is possible to obtain a processed substrate having a recess from the bottom surface of which smears have been sufficiently removed.

[0049] FIG. 1 is a schematic view showing an example of a laser processing apparatus of the present invention. FIG. 2 is a schematic view showing a first processing step in a first example of a laser processing method of the present invention. FIG. 3 is a schematic view showing a second processing step in the first example of a laser processing method of the present invention. FIG. 4 is an enlarged, schematic, partial cross-sectional view showing a recess after the first processing step in the first example of a laser processing method of the present invention. FIG. 5 is an enlarged, schematic, partial cross-sectional view showing a recess after the second processing step in the first example of a laser processing method of the present invention. FIG. 6 is a schematic view showing a second processing step in another example of a laser processing method of the present invention. FIG. 7 is a schematic view showing a second processing step in another example of a laser processing method of the present invention. FIG. 8 is a schematic view showing another example of a laser processing method of the present invention. FIG. 9 is a schematic view showing a first processing step in a second example of a laser processing method of the present invention. FIG. 10 is a schematic view showing a second processing step in the second example of a laser processing method of the present invention.

[0050] As described above, there has been a demand for the development of a laser processing method that can obtain a processed substrate having a recess from which smears on the bottom surface have been sufficiently removed.

[0051] As a result of extensive research into the above-mentioned problems, the inventors have found that a processed substrate having a recess from which smear has been sufficiently removed at its bottom surface can be obtained by performing a first processing step in which an insulating layer of a workpiece is excavated with a first laser beam to form a recess and processing the recess so as to expose a part of the wiring layer at the bottom surface of the recess, and then performing a second processing step in which a second laser beam is used after the first processing step to remove a part of the insulating layer remaining at the bottom surface of the recess and / or smear, which is a processing residue from the first processing step,

[0052] That is, the present invention is a laser processing method for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, the laser processing method comprising: a first processing step of performing an excavation process on the insulating layer of the workpiece with a first laser beam to form a recess so as to expose a part of the wiring layer at the bottom of the recess; and a second processing step of removing, after the first processing step, a part of the insulating layer and / or smear which is a processing residue from the first processing step, remaining at the bottom of the recess, with a second laser beam.

[0053] The present invention also provides a laser processing apparatus that uses a laser beam to form a recess in a workpiece including an insulating layer and a wiring layer, the laser processing apparatus comprising: an oscillator that oscillates a laser beam; and a control device that controls the laser processing apparatus to perform: a first processing stage in which a first laser beam is used to perform an excavation process on the insulating layer of the workpiece to form a recess, and processing is performed so that a part of the wiring layer is exposed at the bottom of the recess; and a second processing stage in which a second laser beam is used after the first processing stage to remove a part of the insulating layer and / or smear, which is a processing residue from the first processing stage, remaining at the bottom of the recess.

[0054] The present invention also provides a method for manufacturing a semiconductor package substrate obtained by a laser processing method that uses a laser beam to form a recess in a workpiece including an insulating layer and a wiring layer, wherein the recess is formed in a semiconductor package substrate precursor as the workpiece, thereby making it possible to obtain a processed substrate having a recess from which smear on the bottom surface has been sufficiently removed, and the method for manufacturing a high-quality semiconductor package substrate with good wiring conductivity, etc., by providing wiring to the wiring layer whose part is exposed through the formed recess.

[0055] The present invention will be described in detail below, but the present invention is not limited thereto.

[0056] [Laser Processing Apparatus] First, an example of the laser processing apparatus of the present invention will be described with reference to Fig. 1. However, the laser processing apparatus of the present invention is not limited to the example shown in Fig. 1.

[0057] 1 is a laser processing apparatus that uses a laser beam to form recesses in a workpiece 10 that includes an insulating layer and a wiring layer. Examples of the workpiece 10 will be described later.

[0058] The laser processing device 100 emits a laser beam L Ａ and a control device 180.

[0059] The control device 180 is a control device that controls the execution of a first processing stage in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess and to expose a portion of the wiring layer at the bottom of the recess, and a second processing stage in which a second laser beam is used after the first processing stage to remove a portion of the insulating layer and / or smear, which is a processing residue from the first processing stage, remaining at the bottom of the recess.

[0060] The first and second processing stages will be described later, but if the laser processing apparatus 100 of the present invention is equipped with a control device 180 that controls the first and second processing stages, it is possible to obtain a processed substrate having a recess from which smears on the bottom surface have been sufficiently removed. For the reason why, please refer to the explanation of the first and second processing stages below.

[0061] Other details of the laser processing apparatus 100 of the example shown in Fig. 1 will be described below. Note that the matters described below also include optional matters for the laser processing apparatus of the present invention.

[0062] The laser processing apparatus 100 includes a first optical function unit 110 , a second optical function unit 120 , a stage 140 that holds the workpiece 10 , and a control device 180 .

[0063] Laser beam L Ａ The oscillator 111 that oscillates the laser beam L Ａ It is a laser light source (laser oscillator) that irradiates (emits)

[0064] The first optical function unit 110 emits a laser beam L ＡThe shaping optical system 112 is irradiated with the laser beam L Ａ For example, the irradiation shape shown in FIG. 1(a) is shaped into the rectangular irradiation shape shown in FIG. 1(b). Ｂ can exhibit a uniform irradiation energy density, for example, a beam profile exhibiting a top hat shape.

[0065] The second optical function unit 120 includes a pattern mask 121. The pattern mask 121 includes an effective area 122 having a pattern corresponding to the region to be processed of the workpiece 10.

[0066] The pattern mask 121 is a mask that reflects the laser beam L Ｂ This mask illumination area may be a portion of the effective area 122 of the pattern mask 121.

[0067] The laser beam L passes through the second optical function unit 120 and has an irradiation shape shown in FIG. Ｃ The traveling direction of the laser beam L is changed by an optional return mirror 150 and is incident on the third optical function unit 130. The laser processing apparatus 100 shown in FIG. 1 irradiates the laser beam L having the irradiation shape shown in FIG. 1(d) from the third optical function unit 130. Ｄ is configured to be irradiated onto a portion of the workpiece 10 held on the stage 140.

[0068] In the example shown in FIG. 1, the third optical function unit 130 includes a projection lens 131 between the second optical function unit 120 and the stage 140 .

[0069] The workpiece 10 is irradiated with the laser beam L which has passed through the pattern mask 121 and the third optical function unit 130. Ｄ The substrate includes an illumination area onto which a pattern is projected.

[0070] In the example of Fig. 1, the mask 121 is configured to be scanned along sweep axes 121X and 121Y shown in Fig. 1. Also, the stage 140 is configured to be scanned along sweep axes 10X and 10Y shown in Fig. 1.

[0071] 1 includes a mask alignment camera 123 as an imaging means for reading characteristic portions of a pattern mask 121, a workpiece alignment camera 160 as an imaging means for reading characteristic portions of a workpiece 10, and an alignment mechanism (not shown). The mask alignment camera 123 is configured to send position information of the characteristic portions of the pattern mask 121 to the alignment mechanism. The workpiece alignment camera 160 is configured to send position information of the characteristic portions of the workpiece 10 to the alignment mechanism. The alignment mechanism is configured to adjust the relative positions of the workpiece 10 and the pattern mask 121 based on this position information.

[0072] By aligning the position of the pattern mask 121 with the position of the workpiece 10 using the imaging means, it is possible to perform recess processing by projecting the mask pattern onto the surface of the workpiece 10 at an accurate position.

[0073] The control device 180 controls, for example, the first optical function unit 110, the pattern mask 121, the stage 141, and the alignment mechanism, and adjusts the position of the first optical function unit 110, i.e., the laser beam L Ａ ~L Ｄ With the position of the optical axis of the laser beam L fixed, the stage 141 and the pattern mask 121 are moved synchronously (i.e., the sweep axis 10X and the sweep axis 121X are synchronized with each other, and the sweep axis 10Y and the sweep axis 121Y are synchronized with each other), thereby Ｄ The scanning irradiation is performed by the scanning irradiation.

[0074] 1 is provided with a beam image detection camera 170 on the stage 140. In the laser processing apparatus 100 shown in Fig. 1, the projection position of the projection image of the pattern mask 121 is acquired by the beam image detection camera 170, and the control device 180 is configured to correct the positional relationship between the stage 140 and the pattern mask 121 based on the information on the projection position.

[0075] Further details of each component of the laser processing apparatus 100 described above will be described later.

[0076] [Laser Processing Method] The laser processing method of the present invention is a laser processing method for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, and includes: a first processing step in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess so as to expose a part of the wiring layer at the bottom of the recess; and a second processing step in which a second laser beam is used after the first processing step to remove a part of the insulating layer and / or smear, which is a processing residue from the first processing step, remaining at the bottom of the recess.

[0077] Hereinafter, several examples of the laser processing method of the present invention will be described with reference to Figures 2 to 11, and also with reference again to Figure 1. However, the laser processing method of the present invention can also be performed using an apparatus other than the laser processing apparatus 100 of the example shown in Figure 1.

[0078] <First Example> The first example is a laser processing method for forming a recess using a laser beam in a workpiece 10 including an insulating layer 1 and a wiring layer 2 shown in FIG. 2(A), more specifically, in a workpiece 10 including an insulating layer 1 and a wiring layer 2 formed of a conductor embedded in the insulating layer 1.

[0079] The workpiece 10 is typically a material substrate for manufacturing a semiconductor package substrate, but is not limited to this.

[0080] The insulating layer 1 typically contains an organic material. Examples of the organic material include epoxy resin, BT resin, and other organic materials that can be contained in insulating layers in semiconductor package substrates. The insulating layer 1 can also contain an inorganic filler, such as silica or alumina. In the present invention, even if the insulating layer 1 contains an inorganic filler, the engraving process (first processing step) and the desmearing process (second processing step) can be successfully performed on the insulating layer 1.

[0081] The wiring layer 2 is formed of a conductor. Examples of the conductor include conductors used in semiconductor package substrates, such as those formed by plating with materials such as copper or nickel. The wiring layer 2 may be, for example, a rewiring layer of the semiconductor package substrate.

[0082] 2A further includes a terminal 3 for externally establishing electrical continuity with the wiring layer 2. The terminal 3 is an optional member.

[0083] [First Processing Stage] In the first processing stage, as shown in FIGS. 2(B) to 2(D) and 3(E), a first laser beam L is applied to the insulating layer 1 of the workpiece 10. １ The recess 4 is formed by performing an excavation process using the insulating layer 1, and a part of the wiring layer 2 is exposed at the bottom of the recess 4. Although not limited to this, the excavation process in the first processing stage is an ablation process for the insulating layer 1.

[0084] First laser beam L １ is, for example, a laser beam L oscillated by an oscillator 111 shown in FIG. 1, passes through a shaping optical system 112 and a projection lens 131 in order, and is irradiated onto the workpiece 10. Ｄ Corresponds to.

[0085] First laser beam L １ It is preferable to use an excimer laser as the laser source. Although the focal depth of an excimer laser is shallow, the use of this laser allows processing with high resolution and high energy density, and recesses can be formed at accurate positions without blurring.

[0086] Furthermore, the excimer laser has a high energy absorption efficiency in the material of the insulating layer 1 (typically an organic material), and therefore, good ablation processing is possible.

[0087] The recess 4 to be formed in the first processing stage has a bottom surface that is, for example, a part of the wiring layer 2 or an extremely thin layer (thin skin) of the insulating layer 1 .

[0088] Therefore, the excavation process performed in the first processing stage to expose a portion of the wiring layer 2 at the bottom of the recess 4 aims to expose a portion of the wiring layer 2 at the bottom of the recess 4, but the formed recess 4 may have a thin insulating film (a portion of the insulating layer 1) with a thickness of, for example, 1 μm or less remaining on the bottom.

[0089] In the first processing stage, it is preferable to process the wiring layer so that the ratio of the area of ​​the exposed portion to the area of ​​the bottom surface of the recess to be formed is large; specifically, it is preferable to expose a portion of the wiring layer over an area of ​​90% or more of the area of ​​the bottom surface of the recess to be formed.

[0090] It is particularly preferable that the first processing step exposes a part of the wiring layer at the bottom of the recess.

[0091] First laser beam L １ The integrated illuminance (total amount of irradiation (energy density) over the irradiation time) of the excavation process by the irradiation method can be, for example, a target integrated illuminance obtained by verifying in advance the integrated illuminance that can expose a part of the wiring layer 2 at the bottom of the recess 4, or an integrated illuminance that is slightly smaller than the target integrated illuminance. For example, a sample having the same configuration as the workpiece 10 is prepared, the insulating layer of this sample is excavated, and the integrated illuminance that can expose a part of the wiring layer 2 at the bottom of the recess 4 can be set as the target integrated illuminance.

[0092] First laser beam L １ Energy density D １ is not particularly limited, but is, for example, 0.5 J / cm ２ 2.0J / cm or more ２ It can be as follows:

[0093] In the first processing step, the first laser beam L １ The irradiation area of ​​one shot of the first laser beam L does not have to be substantially the same as the opening of the recess 4 to be formed. １ The irradiation area of ​​the first laser beam L is a part of the opening of the recess 4 to be formed, and １ The irradiation may result in the formation of recesses 4.

[0094] The irradiation area of ​​one shot may overlap with the irradiation area of ​​another shot. In other words, a part of the irradiation area of ​​one shot may overlap with a part of the irradiation area of ​​another shot. Such irradiation may be called "superimposed irradiation", for example. By performing superimposed irradiation, it is possible to perform an excavation process without gaps in the processing area of ​​the insulating layer 1. The details of superimposed irradiation will be explained later.

[0095] In addition, the first laser beam L is shot multiple times in the same area. １ By irradiating the insulating layer 1 with the light, it is possible to dig the insulating layer 1 in the depth direction as shown in FIGS.

[0096] First laser beam L １ After the irradiation, it is preferable to perform suction and air blowing treatments on the surface of the recess 4 shown in Fig. 3(E) . By performing these treatments, even if an inorganic filler is contained in the insulating layer 1, the inorganic filler can be easily removed.

[0097] [Second Processing Stage] Fig. 4 shows an enlarged schematic cross-sectional view of a portion including the recess 4 surrounded by a dotted line in Fig. 3(E) . The recess 4 shown in Fig. 4 is the recess 4 after suction and air blow treatment.

[0098] 3(E) and 4, after the first processing stage, a part of the insulating layer 1 and / or a smear 1s, which is a processing residue from the first processing stage, may remain on the bottom surface 4s of the recess 4. If such a smear 1s exists on the bottom surface 4s of the recess 4, as explained above, there may be problems such as the plating not adhering well when plating the surface of the recess 4 or the electrical connection between the plating and the wiring layer 2 becoming incomplete.

[0099] Therefore, in the laser processing method of the present invention, after the first processing step, as shown in FIG. 3(F), a second laser beam L ２ Thus, a second processing stage is performed to remove the smear 1s remaining on the bottom surface 4s of the recess 4. That is, the first processing stage and the second processing stage are performed in sequence.

[0100] The removal of such smears is a desmear treatment carried out at the processing stage, and is clearly different from the desmear treatment carried out on a substrate after processing has been completed.

[0101] By the second processing step, a recess 4 having no smear on the bottom surface 4s is obtained, as shown in, for example, FIG. 3(G) and FIG. 5, which is an enlarged schematic cross-sectional view of a portion including the recess 4 surrounded by the dotted line in FIG. 3(G).

[0102] That is, according to the laser processing method of the present invention, it is possible to obtain a processed substrate having a recess 4 from which smears on the bottom surface 4s have been sufficiently removed.

[0103] In the second processing step, the second laser beam L ２ It is preferable to use a pulsed excimer laser beam as the laser source.

[0104] By using an excimer laser with a short wavelength, organic substances contained in part of the insulating layer 1 and / or processing residues can be easily decomposed, and the smear 1s can be efficiently removed.

[0105] Before carrying out the laser processing method of the present invention, a second laser beam L capable of removing the smear 1s while maintaining the outer shape of the recess 4 is applied. ２ It is preferable to verify and set the conditions.

[0106] For example, the second laser beam L used in the second processing step ２ Energy density D ２ The first laser beam L used in the first processing step １ Energy density D １ It is preferable to make it larger.

[0107] The smear contained in the processing residues from VIA processing is located in the VIA processing area, i.e., on the bottom surface 4s of the recess 4, and is therefore less susceptible to the energy of the laser beam than the relatively shallow portion processed in the first processing stage. This reduces the ability to decompose the organic components of the insulating layer 1, which makes it easier for smear to accumulate on the bottom surface 4s.

[0108] Therefore, in the second processing stage, the second laser beam L ２ Energy density D ２The first laser beam L １ Energy density D １ By making it larger, organic components contained in part of the insulating layer 1 and / or processing residues can be efficiently decomposed, and smears on the bottom surface 4s can be efficiently discharged to the outside of the recess 4.

[0109] Also, for example, the second laser beam L used in the second processing step ２ For example, a laser beam emitted from a laser oscillator 111 can be reduced and projected by a projection lens 131 as shown in FIG.

[0110] In the decomposition of organic matter contained in a part of the insulating layer 1 and processing residues in the second processing stage, a very large energy density D ２ In order to obtain a laser beam with such a high energy density at the recess 4, a high energy density is also applied to the pattern mask 121. However, the second laser beam L used in the second processing step ２ If a reduced projection is used as the light source by the projection lens 131, it is possible to suppress the influence on the pattern mask 121 while achieving a large energy density D ２ The second laser beam L ２ Then, the second processing can be carried out.

[0111] Specifically, when the reduction ratio of the projection lens 131 is N, the energy density D in the insulating layer 1 of the workpiece 10 is ２ The energy of the laser beam hitting the pattern mask 121 surface is 1 / (N ２ ) This makes it possible to suppress thermal drift due to the energy of the laser beam, thereby suppressing thermal expansion of the pattern mask 121 and enabling high-precision processing even after a long processing operation.

[0112] In recent years, the processing of substrates has become increasingly finer, and the minimum width of the processing is now required to be several μm. This also affects fine dust particles, and fine dust particles adhering to the mask portion in particular cause a large number of processing defects. Therefore, the pattern mask 121 is enlarged more than the actual processing, and the laser beam L passing through the pattern mask 121 is Ｃ is projected in a reduced size by the projection lens 131 at the subsequent stage, thereby minimizing the effect of minute dust particles.

[0113] Furthermore, deterioration of optical components (for example, the shaping optical system 112 and the pattern mask 121) due to the heat of the laser beam can be suppressed, so the life of the optical components can be extended.

[0114] The projection lens 131 may include a pair of reduction projection lenses. When the projection lens 131 is an infinity optical system, the magnification of the projection lens 131 can be adjusted by, for example, adjusting the ratio of the focal lengths of the reduction projection lenses and the distance between the reduction projection lenses.

[0115] The NA of the reduction projection lens is preferably selected in accordance with the energy density required for processing the workpiece 10. The NA of the reduction projection lens is preferably 0.12 or more.

[0116] It is preferable that the third optical function unit 130 further includes a cooling means for cooling the projection lens 131 .

[0117] By providing a cooling means, it is possible to further suppress the influence of heat due to the laser beam energy in the third optical function unit 130. In the third optical function unit 130, the laser beam that has passed through the pattern mask 121 is projected at a reduced size of 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 onto the pattern mask 121. ２Therefore, by providing the third optical function unit 130 with a cooling function in order to suppress this heat energy, it is possible to suppress the thermal drift caused by the energy of the laser beam, and it becomes possible to perform high-precision processing even after a long processing operation.

[0118] The reduction ratio N of the projection lens 131 is preferably 3 times or more (i.e., the diameter of the laser beam is reduced to 1 / 3), and more preferably 4 times or more (i.e., the diameter of the laser beam is reduced to 1 / 4).

[0119] The second laser beam L used in the second processing step ２ Energy density D ２ 1.0 J / cm ２ It is preferable to set the energy density to be equal to or higher than this.

[0120] In the second processing stage, the energy density D ２ is 1.0 J / cm ２ The second laser beam L ２ By using the above, the smear 1s remaining on the bottom surface 4s of the recess 4 formed in the first processing step can be more reliably removed.

[0121] Energy density D ２ is 1.2 J / cm ２ More preferably, it is 1.5 J / cm or more. ２ It is more preferable that the energy density D ２ The upper limit is not particularly limited, but is 2.0 J / cm ２ It can be as follows:

[0122] In the second processing step, the second laser beam L ２ It is preferable to irradiate the pulsed excimer laser beam five or more times.

[0123] In the second processing step, the second laser beam L ２ By irradiating the pulsed excimer laser beam five or more times, removal of smears on the bottom surface 4 s of the recess 4 can be promoted.

[0124] The number of irradiations is more preferably 10 pulses or more, and even more preferably 15 pulses or more. There is no particular upper limit to the number of irradiations in the second processing stage, but it can be, for example, 30 pulses or less.

[0125] In Fig. 3(F), the optical axis of the second laser beam L2 is aligned with the depth direction of the recess 4 formed in the first processing stage. However, as shown in Fig. 6, in the second processing stage, the optical axis of the second laser beam L2 is aligned with the depth direction of the recess 4 formed in the first processing stage. ２ is preferably incident on the recess 4 at an angle with respect to the depth direction thereof.

[0126] The problem with smear, which is a substance that inhibits conduction, is that present on the bottom surface 4s of the recess 4, which is the VIA processing portion, and this smear inhibits electrical connection between the wiring layer 2 on the bottom surface 4s and the plating layer in the VIA processing portion that will be formed in a subsequent process on the VIA processing portion. Therefore, it is preferable to perform the desmear process, which is the second processing stage, over the entire surface of the bottom surface 4s of the recess 4. However, when the bottom of the recess 4, particularly the aspect ratio of the recess 4, is high, the second laser beam L incident from the opening of the recess 4 (the processing start point of the workpiece 10 in the first processing stage) ２ The wall of the recess 4 becomes an obstacle, and the second laser beam L ２ The energy is difficult to reach.

[0127] Therefore, the second laser beam L ２ By making the laser beam enter the recess 4 from the opening thereof with the optical axis tilted with respect to the depth direction of the recess 4, a high intensity laser beam can be irradiated even near the outer periphery of the bottom surface 4s of the recess 4.

[0128] As a result, smear 1s can be smoothly removed from the entire bottom surface 4s of the recess 4 formed in the first processing stage, and a high-quality semiconductor package substrate with good electrical conductivity can be produced.

[0129] As a result of intensive research, the inventors have found that, for example, by using a wobble unit that is not used in the excavation process or the desmear process but is used in laser welding or the like, it is possible to generate a second laser beam L whose optical axis is inclined with respect to the depth direction of the recess 4. ２It has been found that the light can be irradiated onto the bottom surface 4 s of the recess 4 while rotating the laser beam around an axis in the depth direction of the recess 4 .

[0130] In addition, in the second processing stage, it is preferable to irradiate the bottom surface 4s of the recess 4 with the pulsed excimer laser beam multiple times by performing scan irradiation so that part of the irradiation area with one pulsed excimer laser beam overlaps part of the irradiation area with another pulsed excimer laser beam.

[0131] Such scanning irradiation corresponds to the previously explained "superimposed irradiation." Here, an example of superimposed irradiation in the second processing stage will be described with reference to FIG.

[0132] FIG. 7(a) shows the second laser beam L ２ In the superimposed irradiation, as shown in FIG. 7, one shot, that is, one pulse of the second laser beam L ２－１ A part of the irradiated area by another shot, i.e., another pulsed second laser beam L ２－２ and L ２－３ 7 shows the overlapping along the direction 10X of the workpiece 10, but the overlapping irradiation along the direction 10Y shown in FIG.

[0133] According to the laser processing method of this preferred embodiment, in the second processing stage, the smear 1s can be removed seamlessly from the entire bottom surface 4s of the recess 4 formed in the first processing stage.

[0134] In this case, it is more preferable to perform the above-mentioned scanning irradiation by using, for example, a first optical function unit 110, a stage 140 for holding the workpiece 10, and a pattern mask 121 having a pattern corresponding to the recess 4 to be formed, as shown in Figure 1, and moving the stage 140 and the pattern mask 121 in synchronization while fixing the position of the first optical function unit 110.

[0135] In laser drilling, a scanner is used to perform the hole drilling process, so even when the first and second processing stages are performed consecutively, slight misalignment occurs depending on the positional accuracy of the scanner, and even if an attempt is made to remove smear, which is processing residue from the entire bottom surface of the recess, there is a possibility that some part will remain. Furthermore, with the recent increase in density of semiconductor package substrates, the laser VIA processing density has dramatically increased, and in VIA processing using a scanner with a laser drill, whether the first processing stage or the second processing stage is performed, the processing time becomes dramatically longer as the number of processes increases.

[0136] On the other hand, according to the overlapping scan irradiation according to the more preferred embodiment described herein, the smear removal (desmearing) step in the second processing stage can be carried out as an extension of the stepwise ablation processing in the first processing stage, and no misalignment occurs between them. As a result, smear can be removed from the entire bottom surface 4 s of the recess 4.

[0137] Furthermore, with the overlapping scan irradiation according to the more preferred embodiment described herein, even if the VIA processing density increases due to the increased density of the semiconductor package substrate, it is only necessary to change the mask pattern, and the processing time does not increase. This also applies to the second processing stage, making it possible to remove high-density smears at high speed.

[0138] That is, in the laser processing method according to this more preferred embodiment, in the second processing stage, smear can be removed more thoroughly from the entire bottom surface of the recess formed in the first processing stage.

[0139] Such superimposed irradiation can be controlled, for example, by the control device 180. As described above, superimposed irradiation can also be performed in the first processing stage.

[0140] It is preferable that the first and second processing stages described above are carried out consecutively using the same laser oscillator.

[0141] By continuously performing the first processing stage and the second processing stage using the same laser oscillator (for example, oscillator 111 shown in FIG. 1 ), it is possible to efficiently form recesses 4 without smears on the bottom surface 4 s without having to perform a process such as a setup change. A manufacturing method for semiconductor package substrates incorporating such a preferred embodiment of the laser processing method can efficiently produce high-quality semiconductor package substrates with good wiring conductivity, etc.

[0142] When an exposure machine is used, the engraving process and the desmearing process must be carried out separately. On the other hand, in the laser processing method of the present invention, the first processing step, that is, the (VIA) engraving process, can be performed by direct ablation, so that the first processing step and the second processing step can be carried out continuously using the same laser oscillator.

[0143] It is of course possible to carry out the first processing step and the second processing step in separate devices.

[0144] In the laser processing method of the present invention, the second processing step is carried out after the first processing step, that is, the first processing step and the second processing step are carried out in sequence, and various modifications are possible.

[0145] For example, the first processing step may be performed multiple times. The irradiation areas from multiple first processing steps may overlap each other as described above. In this case, the second processing step may be performed each time after performing one first processing step, or the second processing step may be performed after performing multiple first processing steps. An example of the former is shown in FIG. 8, and an example of the latter is shown in FIG. 9.

[0146] In the example shown in FIG. 8, first, as shown in FIG. 8(I), a recess 4 is formed by the first machining step. １ Next, as shown in FIG. 8(II), the first second processing step is carried out to form the recess 4 １ Next, as shown in FIG. 8(III), the second first processing step is carried out to remove the smear on the bottom surface of the recess 4. １ The recess 4 is formed so as to overlap with a part of the recess 4. ２ Then, as shown in FIG. 8(IV), a second processing step is carried out to form a recess 4. ２ Remove the smear from the bottom of the

[0147] On the other hand, in the example shown in FIG. 9, FIG. 9(I') is the same as FIG. 8(1), but then, as shown in FIG. 9(II'), the second machining step is not performed, and the first machining step is performed for the second time to form the recess 4. １ The recess 4 is formed so as to overlap with a part of the recess 4. ２ Then, as shown in FIG. 9(III′), a second processing step is carried out to form recesses 4 １ and recess 4 ２ Remove the smear on the bottom.

[0148] 8 and 9 show an example in which the first processing step is performed twice, but the number of times the first processing step is performed in the overlapping irradiation is not particularly limited. For example, when performing a total of eight first processing steps, the second processing step may be performed after each first processing step, or after two or four first processing steps, or after a total of eight first processing steps, one second processing step may be performed. The overlapping direction may also be not only one direction, but also two directions perpendicular to each other.

[0149] Furthermore, in the above, a laser processing method has been described in which the workpiece 10 to be processed includes an insulating layer 1 and a wiring layer 2 formed of a conductor embedded in the insulating layer 1. However, the workpiece 10 may be any workpiece 10 that includes the insulating layer 1 and the wiring layer 2, and the wiring layer 2 does not need to be embedded in the insulating layer 1.

[0150] For example, it is also possible to process a workpiece 10 including an insulating layer 1 and a wiring layer 2 formed on one surface of the insulating layer 1, as shown in Fig. 10(A'). That is, in the workpiece 10 shown in Fig. 10(A'), the wiring layer 2 is not embedded in the insulating layer 1.

[0151] Even with such a workpiece 10, for example, as shown in Figures 10(B') to (D'), a first processing stage can be performed on the surface 1a of the insulating layer 1 opposite to the surface on which the wiring layer 2 is provided, to perform an excavation process, and then, as shown in Figures 11(E') to (G'), a second processing stage can be performed on the recess 4 formed in the first processing stage.

[0152] In the laser processing method of the present invention, in the second processing stage, for example, a pattern mask 121 is used to apply the second laser beam L ２ The recesses 4 can be selectively irradiated with the light. Irradiation in this manner is clearly different from photodesmearing, in which UV light or the like is irradiated onto the entire surface of the substrate.

[0153] [Method for manufacturing semiconductor package substrate] The method for manufacturing a semiconductor package substrate of the present invention includes: forming a recess in a semiconductor package substrate precursor as the workpiece by the laser processing method of the present invention; and providing wiring to a wiring layer that is partially exposed through the formed recess.

[0154] In the method for manufacturing a semiconductor package substrate of the present invention, a recess is formed in a semiconductor package substrate precursor by the laser processing method of the present invention, so that a processed substrate having a recess from which smear on the bottom surface has been sufficiently removed can be obtained, and as a result, a high-quality semiconductor package substrate with good wiring conductivity, etc. can be efficiently produced.

[0155] However, the laser processing method of the present invention can be applied to methods other than the manufacturing method of semiconductor package substrates.

[0156] This specification includes the following aspects. [1] A laser processing method for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, the laser processing method comprising: a first processing step in which a first laser beam is used to carve the insulating layer of the workpiece to form a recess so as to expose a portion of the wiring layer at the bottom of the recess; and a second processing step in which a second laser beam is used after the first processing step to remove a portion of the insulating layer and / or a smear, which is a processing residue from the first processing step, remaining at the bottom of the recess. [2] The laser processing method described in [1], in which, in the first processing step, the portion of the wiring layer is exposed over an area of ​​90% or more of the area of ​​the bottom of the recess to be formed. [3] The laser processing method described in [1], in which the portion of the wiring layer is exposed at the bottom of the recess by the first processing step. [4] The laser processing method described in any one of [1] to [3], in which the first processing step and the second processing step are performed continuously using the same laser oscillator. [5] The laser processing method according to any one of [1] to [4], in which the insulating layer containing an organic substance and an inorganic filler is processed. [6] The laser processing method according to any one of [1] to [5], in which a pulsed excimer laser beam is used as the second laser beam in the second processing stage. [7] The laser processing method according to any one of [1] to [6], in which the energy density of the second laser beam used in the second processing stage is made higher than the energy density of the first laser beam used in the first processing stage. [8] The laser processing method according to any one of [1] to [7], in which a laser beam from a laser oscillator is used as the second laser beam used in the second processing stage, which is reduced and projected by a projection lens. [9] The laser processing method according to any one of [1] to [7], in which the energy density of the second laser beam used in the second processing stage is made higher than the energy density of the first laser beam used in the first processing stage. ２

[10] The laser processing method according to any one of [1] to [8], wherein the energy density is set to be equal to or greater than 100 kHz.

[10] The laser processing method according to [6], wherein, in the second processing stage, the pulsed excimer laser beam is irradiated five or more times.

[11] The laser processing method according to any one of [1] to

[10] , characterized in that, in the second processing stage, the second laser beam is incident at an angle with respect to the depth direction of the recess formed in the first processing stage.

[12] The laser processing method according to [6], wherein, in the second processing stage, the pulsed excimer laser beam is irradiated multiple times onto the bottom surface of the recess by performing scan irradiation such that a portion of an irradiation area with one pulsed excimer laser beam overlaps a portion of an irradiation area with another pulsed excimer laser beam.

[13] The laser processing method according to

[12] , wherein the scanning irradiation is performed by using an optical system including an oscillator that oscillates the second laser beam, a stage that holds the workpiece, and a pattern mask having a pattern corresponding to the recess to be formed, and the stage and the pattern mask are moved synchronously while keeping the position of the optical system fixed.

[14] A method for manufacturing a semiconductor package substrate, comprising: forming a recess in a semiconductor package substrate precursor as the workpiece by the laser processing method according to any one of [1] to

[13] , and providing wiring to a wiring layer that is partially exposed through the formed recess.

[15] A laser processing apparatus for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, the laser processing apparatus comprising: an oscillator for emitting a laser beam; and a control device for controlling the laser processing apparatus to perform: a first processing stage in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess and to expose a part of the wiring layer at the bottom of the recess; and a second processing stage in which a second laser beam is used after the first processing stage to remove a part of the insulating layer and / or smear, which is a processing residue from the first processing stage, remaining at the bottom of the recess.

[0157] 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. A laser processing method for forming a recess using a laser beam in a workpiece including an insulating layer and a wiring layer, comprising: a first processing step in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess so that a part of the wiring layer is exposed at the bottom of the recess; and a second processing step in which, after the first processing step, a second laser beam is used to remove a part of the insulating layer and / or smear, which is a processing residue from the first processing step, remaining at the bottom of the recess.

2. A laser processing method according to claim 1, wherein in the first processing stage, the portion of the wiring layer is exposed over an area that is 90% or more of the area of ​​the bottom surface of the recess to be formed.

3. The laser processing method according to claim 1, wherein the first processing step exposes the portion of the wiring layer at the bottom of the recess.

4. The laser processing method according to claim 1, wherein the first processing stage and the second processing stage are carried out consecutively using the same laser oscillator.

5. The laser processing method according to claim 1, wherein the insulating layer contains an organic material and an inorganic filler.

6. The laser processing method according to claim 1, wherein a pulsed excimer laser beam is used as the second laser beam in the second processing step.

7. The laser processing method according to claim 1, wherein the energy density of the second laser beam used in the second processing stage is set to be greater than the energy density of the first laser beam used in the first processing stage.

8. A laser processing method according to claim 7, wherein the second laser beam used in the second processing step is a laser beam emitted from a laser oscillator and projected by a projection lens in a reduced size.

9. The energy density of the second laser beam used in the second processing step is set to 1.0 J / cm ２ 8. The laser processing method according to claim 7, wherein the energy density is equal to or greater than 800 .mu.m.

10. The laser processing method according to claim 6, wherein the pulsed excimer laser beam is irradiated five or more times in the second processing stage.

11. A laser processing method according to claim 1, characterized in that in the second processing step, the second laser beam is incident at an angle with respect to the depth direction of the recess formed in the first processing step.

12. A laser processing method according to claim 6, wherein in the second processing stage, scanning irradiation is performed so that a portion of an irradiated area by one pulsed excimer laser beam overlaps a portion of an irradiated area by another pulsed excimer laser beam, thereby irradiating the bottom surface of the recess with the pulsed excimer laser beam multiple times.

13. A laser processing method according to claim 12, using an optical system including an oscillator that oscillates the second laser beam, a stage that holds the workpiece, and a pattern mask having a pattern corresponding to the recess to be formed, wherein the scanning irradiation is performed by moving the stage and the pattern mask in synchronization while the position of the optical system is fixed.

14. A method for manufacturing a semiconductor package substrate, comprising: forming a recess in a semiconductor package substrate precursor as the workpiece by the laser processing method according to any one of claims 1 to 13; and providing wiring to a wiring layer partially exposed through the formed recess.

15. A laser processing device that uses a laser beam to form a recess in a workpiece including an insulating layer and a wiring layer, comprising: an oscillator that oscillates a laser beam; and a control device that controls the laser processing device to perform: a first processing stage in which a first laser beam is used to carve into the insulating layer of the workpiece to form a recess and expose a part of the wiring layer at the bottom of the recess; and a second processing stage in which a second laser beam is used after the first processing stage to remove a part of the insulating layer and / or processing residue from the first processing stage that remains at the bottom of the recess.

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