Method for manufacturing semiconductor packages

Abstract

Disclosed is a method for manufacturing a semiconductor package 100. In this method, for example, surface treatment is performed by irradiating, with an oxygen plasma (plasma P), the surface of an insulating resin layer 20 on a printed wiring board which is a substrate 10. The insulating resin layer 20 is formed of, for example, a solder resist including an inorganic filler. The inorganic filler 22, which is deposited on the surface of the solder resist by the irradiation with the plasma P, is removed by ultrasonic cleaning. Thereafter, a plating layer 30 is formed by electroless plating on the solder resist from which the inorganic filler 22 has been removed. With this method, since the inorganic filler that affects electroless plating has been removed, an electroless plating can be reliably deposited on the surface of the solder resist.

Description

Semiconductor package manufacturing method

[0001] The present disclosure relates to a method for manufacturing a semiconductor package.

[0002] Chip-to-chip or interposer-chip interconnect technology is used to increase the speed of signal transmission in semiconductor packages. Furthermore, package-on-package technology is used in smartphones and tablet devices, in which different packages are connected by stacking them on a semiconductor device for high-speed signal transmission using flip-chip mounting. Furthermore, as a method for forming wiring at high density and low cost, the ETS (Embedded Trace Substrate) method has been proposed (see, for example, Non-Patent Document 1). In this ETS method, a wiring circuit is formed by forming a seed layer on an organic substrate by sputtering. The wiring circuit is then embedded in an insulating material, and the copper foil is then dissolved and removed, thereby forming a circuit board.

[0003] JP 2022-030643 A

[0004] V. Lin, V. Lin, N. Kao, DS Jiang and CS Hsiao, "Chip scale package with low cost substrate evaluation and characterization," 2014 IEEE 16th Electronics Packaging Technology Conference (EPTC), Singapore, 2014, pp. 421-425, doi: 10.1109 / EPTC.2014.7028302.

[0005] In semiconductor package manufacturing methods, a seed layer for wiring circuits is sometimes formed by sputtering, but sputtering methods make it difficult to improve productivity and increase manufacturing costs. Therefore, instead of sputtering, forming the seed layer by electroless plating is considered. This method makes it easier to improve productivity. However, there is a problem in that it is difficult to apply electroless plating to an insulating resin layer.

[0006] An object of the present disclosure is to provide a method for manufacturing a semiconductor package that can reliably form electroless plating on an insulating resin layer containing an inorganic filler.

[0007] [1] In one aspect, the present disclosure provides a method for manufacturing a semiconductor package, the method comprising the steps of: performing a surface treatment on a surface of an insulating resin layer on a substrate by irradiating the surface with oxygen plasma, the insulating resin layer including an inorganic filler; removing at least a portion of the inorganic filler deposited on the surface of the insulating resin layer; and forming a plating layer by electroless plating on at least a portion of the surface of the insulating resin layer from which the inorganic filler has been removed.

[0008] According to the inventors' research, one of the reasons why electroless plating does not adhere well to an insulating resin layer is that inorganic fillers contained in the resin composition forming the insulating resin layer precipitate on the surface of the insulating resin layer. Therefore, in the semiconductor device manufacturing method according to the above [1], the surface of the insulating resin layer containing the inorganic filler is irradiated with oxygen plasma to perform surface treatment, and at least a portion of the inorganic filler precipitated on the surface of the insulating resin layer is removed. In this case, the inorganic filler that affects plating adhesion is removed from the surface of the insulating resin layer, allowing a plating layer to be reliably formed on the surface of the insulating resin layer by electroless plating. Furthermore, the inorganic filler present in areas other than the surface is not removed, thereby maintaining the purpose of including the inorganic filler, such as suppressing warping of the insulating resin layer. Furthermore, the detachment of the inorganic filler creates microscopic irregularities, which is expected to improve plating adhesion through an anchoring effect.

[0009] [2] In another aspect, the present disclosure provides another method for manufacturing a semiconductor package, the method comprising the steps of: performing surface treatment on a surface of an insulating resin layer on a substrate by irradiating the surface with plasma, the insulating resin layer including an inorganic filler; removing at least a portion of the inorganic filler deposited on the surface of the insulating resin layer; and forming a plating layer by electroless plating on at least a portion of the surface of the insulating resin layer from which the inorganic filler has been removed.

[0010] In the method for manufacturing a semiconductor package according to [2], the surface of the insulating resin layer containing the inorganic filler is irradiated with plasma to perform surface treatment, and at least a portion of the inorganic filler precipitated on the surface of the insulating resin layer is removed. In this case, the inorganic filler that affects the adhesion of plating is removed from the surface of the insulating resin layer, so that a plating layer can be reliably formed on the surface of the insulating resin layer by electroless plating.

[0011] [3] In the semiconductor package manufacturing method of [1] or [2] above, the plasma irradiation time is preferably 0.5 to 10 minutes. A plasma irradiation time of 0.5 minutes or more precipitates much of the inorganic filler on the surface of the insulating resin layer, making it easier for the catalyst to adsorb, and facilitating subsequent removal of the inorganic filler. This ensures reliable formation of a plating layer by electroless plating. On the other hand, a plasma irradiation time of 10 minutes or less prevents the surface of the insulating resin layer from being excessively scraped and becoming excessively rough. Excessive roughening of the surface of the insulating resin layer can lead to uneven shapes of the wiring electrodes, including electroless plating, formed thereon, potentially deteriorating transmission characteristics at high frequencies. However, limiting the plasma irradiation time to 10 minutes or less can also suppress such deterioration of transmission characteristics.

[0012] [4] In yet another aspect, the present disclosure provides another method for manufacturing a semiconductor package, the method including the steps of: performing a surface treatment to activate the surface of an insulating resin layer on a substrate, the insulating resin layer containing an inorganic filler; removing at least a portion of the inorganic filler deposited on the surface of the insulating resin layer; and forming a plating layer by electroless plating on at least a portion of the surface of the insulating resin layer from which the inorganic filler has been removed.

[0013] In the method for manufacturing a semiconductor package according to [4], a treatment is performed to activate the surface of the insulating resin layer containing the inorganic filler, and at least a portion of the inorganic filler precipitated on the surface of the insulating resin layer is removed. In this case, the inorganic filler that affects the adhesion of plating is removed from the surface of the insulating resin layer, so that a plating layer can be reliably formed on the surface of the insulating resin layer by electroless plating.

[0014] [5] In the method for manufacturing a semiconductor package according to any one of the above [1] to [4], the resin composition forming the insulating resin layer may contain an alkali-soluble resin.

[0015] [6] In the method for manufacturing a semiconductor package according to [4] above, it is preferable to perform a desmear treatment on the insulating resin layer in the surface treatment step. In this case, the inorganic filler can be reliably precipitated on the surface of the insulating resin layer, facilitating the necessary removal of the inorganic filler. Therefore, a plating layer can be reliably formed on the surface of the insulating resin layer by electroless plating.

[0016] [7] In the method for manufacturing a semiconductor package according to any one of [1] to [6] above, in the surface treatment step, it is preferable to repeat at least one of plasma treatment and desmear treatment to form an irregular shape on the surface of the insulating resin layer and precipitate the inorganic filler. In this case, the inorganic filler can be reliably precipitated on the surface of the insulating resin layer, facilitating necessary removal of the inorganic filler. Therefore, a plating layer can be reliably formed on the surface of the insulating resin layer by electroless plating.

[0017] [8] In the semiconductor package manufacturing method according to any one of [1] to [7] above, the step of removing the inorganic filler preferably involves ultrasonic cleaning of the insulating resin layer. In this case, the inorganic filler deposited on the surface of the insulating resin layer can be efficiently removed, and the influence on portions other than the inorganic filler can be reduced. Therefore, a plating layer can be reliably formed on the surface of the insulating resin layer by electroless plating.

[0018] [9] In the method for manufacturing a semiconductor package according to [8] above, the ultrasonic cleaning in the step of removing the inorganic filler is preferably performed during the electroless plating process in the step of forming the plating layer. In this case, the removal of the inorganic filler and the formation of the plating layer can be performed in parallel, allowing for efficient processing.

[0019]

[10] In the semiconductor package manufacturing method of [8] or [9] above, the ultrasonic cleaning time is preferably 5 to 10 minutes. By performing ultrasonic cleaning for 5 minutes or more, inorganic filler precipitated on the surface of the insulating resin layer can be reliably removed. On the other hand, by performing ultrasonic cleaning for 10 minutes or less, residual cleaning solution (cleaner) components on the insulating resin layer can be prevented, thereby reducing the impact of residual cleaning solution on plating adhesion. Furthermore, if the immersion time in the cleaning solution is longer than 10 minutes, moisture in the cleaning solution may penetrate into the insulating resin layer, and the moisture may evaporate during annealing (heating) after plating, resulting in the formation of voids. However, if the cleaning time is within 10 minutes, the formation of such voids can be suppressed.

[0020]

[11] In the method for manufacturing a semiconductor package according to any one of the above [1] to [8], the step of forming a plating layer may be performed after the step of removing the inorganic filler. In this case, the plating layer is formed after removing the inorganic filler that affects the formation of the plating, so that the plating layer can be formed more reliably.

[0021]

[12] In the method for manufacturing a semiconductor package according to any one of [1] to

[11] above, the content of the inorganic filler contained in the resin composition forming the insulating resin layer may be 60% by mass to 80% by mass based on the total amount of solids contained in the insulating resin layer before curing. Having an inorganic filler content of 60% by mass or more can improve reliability. On the other hand, having an inorganic filler content of 80% by mass or less can prevent embrittlement.

[0022]

[13] The method for manufacturing a semiconductor package according to any one of [1] to

[12] above may further include a step of forming an insulating resin layer by disposing a solder resist on the surface of a printed wiring board or a substrate that is a package substrate. In this case, a plating layer can be reliably formed on the solder resist by electroless plating.

[0023]

[14] The method for manufacturing a semiconductor package according to any one of [1] to

[13] above may further include the steps of: forming an electrode exposed from the insulating resin layer using the plating layer as a seed layer after forming the plating layer; and mounting a semiconductor element provided with a terminal electrode on the insulating resin layer, in which the electrode is connected to the terminal electrode.

[0024] According to the present disclosure, it is possible to provide a method for manufacturing a semiconductor package that can reliably form electroless plating on an insulating resin layer containing an inorganic filler.

[0025] Figures 1(a) and (b) are cross-sectional views showing a method for manufacturing a semiconductor package according to an embodiment of the present invention. Figures 2(a) and (b) are cross-sectional views showing a method for manufacturing a semiconductor package according to an embodiment of the present invention, showing steps performed after the step shown in Figure 1(b). Figures 3(a) to 3(c) are cross-sectional views showing a method for manufacturing a semiconductor package according to an embodiment of the present invention, showing steps performed after the step shown in Figure 2(b).

[0026] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent parts will be denoted by the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0027] In this specification, the term "layer" includes not only a structure having a shape formed over the entire surface when observed in a plan view, but also a structure having a shape formed on a portion thereof. In this specification, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0028] In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in one stage may be replaced with the upper or lower limit of a numerical range in another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples.

[0029] A method for manufacturing a semiconductor package according to this embodiment will be described with reference to Figures 1 to 3. Figures 1(a) and 1(b) are cross-sectional views showing a method for manufacturing a semiconductor package according to one embodiment of the present invention. Figures 2(a) and 2(b) are cross-sectional views showing a method for manufacturing a semiconductor package according to one embodiment of the present invention, showing steps performed after the step shown in Figure 1(b). Figures 3(a) to 3(c) are cross-sectional views showing a method for manufacturing a semiconductor package according to one embodiment of the present invention, showing steps performed after the step shown in Figure 2(b).

[0030] 1A, a substrate 10 is first prepared. The substrate 10 may be, for example, an insulating substrate such as a printed wiring board or a package substrate, and may include a build-up layer. As the insulating substrate, a glass substrate or a substrate made of a cured product of an epoxy resin composition may be used.

[0031] Next, as shown in FIG. 1A, an insulating resin layer 20 is formed on the surface 11 of the substrate 10 using an insulating material. The insulating material constituting the insulating resin layer 20 may be either a liquid or film-like insulating material. When a film-like insulating material is disposed on the surface 11 of the substrate 10, lamination is preferably performed at a low temperature (e.g., 40°C to 120°C). In this case, a photosensitive or thermosetting insulating resin film that can be laminated at 40°C to 120°C can be used. By using an insulating film that can be laminated at a temperature of 40°C or higher, processing such as lamination can be performed without worrying about tackiness at room temperature, thereby improving handleability. Furthermore, by using an insulating film that can be laminated at a temperature of 120°C or lower, warping after lamination can be suppressed.

[0032] The resin composition constituting such an insulating material may contain an acrylic resin, an epoxy resin, an epoxy-acrylic mixed resin, a urethane resin, or a melamine resin. Such a resin composition preferably contains an acrylic resin, an epoxy resin, or an epoxy-alkali mixed resin. Furthermore, such an insulating material may be, for example, a solder resist, and the resin composition forming the insulating resin layer 20 may contain an alkali-soluble resin or an inorganic filler. The content of the inorganic filler contained in the insulating resin layer 20 is preferably 60% by mass to 80% by mass based on the total solid content contained in the insulating resin layer 20 before curing. Furthermore, the thickness of the insulating resin layer 20 may be, for example, 15 μm to 30 μm. The insulating resin layer 20 may also be formed from a liquid insulating material. In this case, it can be formed from the same material as the insulating film. In the case of a liquid insulating material, the insulating resin layer 20 can be formed by applying the liquid insulating material to the substrate 10 and curing it.

[0033] Subsequently, after the insulating resin layer 20 is formed, as shown in (b) of Fig. 1, a plasma treatment or a desmear treatment is performed on the surface of the insulating resin layer 20. By performing such a treatment, polar groups are exposed and activated on the surface of the insulating resin layer 20, resulting in an uneven shape.

[0034] In the plasma treatment step, the surface of the insulating resin layer 20 on the substrate 10 is irradiated with plasma P to perform the surface treatment. The gas species used in this plasma treatment include, for example, oxygen plasma, argon (Ar) plasma, and nitrogen (N ２ The plasma used in this embodiment may be any of oxygen (O) plasma, helium (He) plasma, and fluorine-containing plasma, or two or more different types of plasma may be used. ２ Preferably, plasma, Ar plasma, or He plasma is used. In the step of performing plasma treatment, one or more plasma treatments may be repeated.

[0035] The plasma irradiation time may be, for example, 0.5 to 10 minutes, 2 to 10 minutes, or 5 to 10 minutes. Plasma irradiation for 0.5 minutes or longer precipitates much of the inorganic filler on the surface 21 of the insulating resin layer 20a (see FIG. 2(a)), making it easier for the catalyst to adsorb, and facilitating subsequent removal of the inorganic filler. This ensures reliable formation of a plating layer by electroless plating. On the other hand, plasma irradiation for 10 minutes or less prevents excessive scraping of the surface 21 of the insulating resin layer 20a and excessive surface roughening. Excessive roughening of the surface of the insulating resin layer 20a can result in uneven shapes of the wiring electrodes, including electroless plating, formed thereon, potentially degrading transmission characteristics at high frequencies. However, limiting the plasma irradiation time to 10 minutes or less can also suppress such degradation of transmission characteristics.

[0036] On the other hand, when a desmear treatment is used, the desmear treatment includes a swelling treatment step and a roughening treatment step. In the swelling treatment step, the substrate 10 and the insulating resin layer 20 integrated together are positioned so that at least the surface 21 of the insulating resin layer 20 is immersed in a desmear treatment solution. A predetermined swelling treatment is then performed. The swelling treatment time is not particularly limited, but is preferably between 30 seconds and 15 minutes, and more preferably between 1 minute and 10 minutes. The swelling treatment temperature varies depending on the type or concentration of the organic compound contained in the swelling solution, but is preferably, for example, 40°C to 90°C. After the swelling treatment is completed, a predetermined roughening treatment is performed. The roughening treatment time is not particularly limited, but is preferably between 3 minutes and 25 minutes, and more preferably between 5 minutes and 20 minutes. The roughening treatment temperature varies depending on the type or concentration of the organic compound contained in the roughening solution, but is preferably, for example, 50°C to 80°C. Known swelling solutions and roughening solutions can be used for the desmear treatment. By setting the desmearing time to 3 minutes or more, much of the inorganic filler 22 is precipitated on the surface 21 of the insulating resin layer 20a, and the surface is easily adsorbed by the catalyst, facilitating subsequent removal of the inorganic filler 22. This ensures reliable formation of a plating layer by electroless plating. On the other hand, by setting the desmearing time to 25 minutes or less, it is possible to prevent the surface 21 of the insulating resin layer 20a from being scraped more than necessary and becoming excessively rough. This makes it possible to suppress deterioration of the transmission characteristics of the semiconductor device to be fabricated. Furthermore, the desmearing process may be repeated.

[0037] Next, the surface 21 of the insulating resin layer 20a is activated by plasma treatment or desmear treatment, and as shown in FIG. 2A, the inorganic filler 22 precipitates on the surface 21 of the insulating resin layer 20a. Then, the inorganic filler 22 precipitated on the surface 21 of the insulating resin layer 20a is removed by a predetermined process. According to the inventor's research, one of the reasons why electroless plating (described later) is difficult to adhere to the insulating resin layer 20a is the inorganic filler 22 precipitated on the surface 21 of the insulating resin layer 20a, among the inorganic fillers 22 contained in the resin composition forming the insulating resin layer 20a. Therefore, in this removal process, such inorganic filler 22 is removed. For example, ultrasonic cleaning can be used as a removal method. In ultrasonic cleaning, the surface 21 of the insulating resin layer 20 is immersed in at least a cleaning solution, and ultrasonic waves are applied to the cleaning solution. The cleaning solution is, for example, pure water. The cleaning time for ultrasonic cleaning is, for example, 5 to 10 minutes. By such ultrasonic cleaning, the inorganic filler 22 precipitated (exposed) on the surface 21 of the insulating resin layer 20 is removed. Note that inorganic fillers other than the inorganic filler 22 precipitated on the surface 21 are not removed. The frequency at which ultrasonic vibrations are applied in the ultrasonic cleaning is, for example, 20 KHz to 150 KHz. Note that the ultrasonic cleaning may be performed in the step of performing the electroless plating treatment described below (for example, a pre-cleaning step for electroless plating). In this case, the cleaning liquid may be a cleaner liquid used to clean the surface of the insulating resin layer 20 in the electroless plating treatment.

[0038] Next, after the inorganic filler 22 deposited on the surface 21 of the insulating resin layer 20a is removed, a plating layer 30 is formed by electroless plating on the surface 21 of the insulating resin layer 20b from which the inorganic filler has been removed, as shown in Figure 2(b). The electroless plating process used here may be displacement plating or autocatalytic plating. The plating layer 30 is made of a plating material selected from Cu, Sn, Au, Ag, Pd, and Ni, and is formed by laminating one or more of these.

[0039] The thickness of the plating layer 30 formed by electroless plating is preferably in the range of 50 nm to 500 nm, for example. When the thickness of the plating layer 30 is 50 nm or more, the resistance during power supply can be reduced when forming a metal layer by electrolytic plating, allowing for efficient electrolytic plating. On the other hand, when the thickness of the plating layer 30 is 500 nm or less, the removal time can be shortened when partially removing the plating layer 30.

[0040] Next, after the plating layer 30 is formed by electroless plating, unnecessary portions of the plating layer 30 are removed by etching or other means to form a plating layer 30a, as shown in Fig. 3A. The electrode 40 is then formed by electrolytic plating or other means using the plating layer 30a as a seed layer. The electrode 40 can be made of, for example, copper. The plating layer 30a (electrode 40) is electrically connected to wiring electrodes formed on the substrate 10 or to built-in electronic components (not shown).

[0041] Next, after the electrodes 40 are formed, a semiconductor element 50 having a plurality of terminal electrodes formed on its underside is prepared, and the semiconductor element 50 is mounted on the insulating resin layer 20b as shown in FIG. 3B. At this time, the electrodes 40 are connected to the terminal electrodes of the semiconductor element 50. Thereafter, as shown in FIG. 3C, an underfill agent 60 (CUF or the like) is injected between the insulating resin layer 20b and the semiconductor element 50 and cured. In this manner, a semiconductor package 100 having the semiconductor element 50 mounted thereon is manufactured.

[0042] As described above, according to the method for manufacturing a semiconductor package according to this embodiment, the surface 21 of the insulating resin layer 20 containing the inorganic filler 22 is irradiated with plasma P such as oxygen plasma to perform surface treatment, and the inorganic filler 22 deposited on the surface 21 of the insulating resin layer 20a is removed. In this way, the inorganic filler 22 that affects the adhesion of plating is removed from the surface 21 of the insulating resin layer 20a, so that the plating layer 30 can be reliably formed on the surface 21 of the insulating resin layer 20b by electroless plating.

[0043] In the semiconductor package manufacturing method according to this embodiment, the plasma P irradiation time is preferably 0.5 to 10 minutes. Plasma P irradiation times of 0.5 minutes or longer precipitate much of the inorganic filler 22 on the surface 21 of the insulating resin layer 20, making it easier for the catalyst to adsorb, and facilitating subsequent removal of the inorganic filler 22. This ensures reliable formation of the plating layer 30 by electroless plating. Meanwhile, plasma P irradiation times of 10 minutes or less prevent the surface of the insulating resin layer 20 from being excessively scraped and becoming excessively rough. Excessive roughening of the surface of the insulating resin layer 20 can result in uneven shapes of the wiring electrodes, including electroless plating, formed thereon, potentially degrading transmission characteristics at high frequencies. However, limiting the plasma irradiation time to 10 minutes or less can also prevent such degradation of transmission characteristics.

[0044] In the semiconductor package manufacturing method according to this embodiment, the step of removing the inorganic filler 22 preferably involves ultrasonic cleaning of the insulating resin layer 20a. This effectively removes the inorganic filler 22 deposited on the surface 21 of the insulating resin layer 20a while minimizing the impact on areas other than the inorganic filler 22. This ensures that the plating layer 30 is reliably formed on the surface 21 of the insulating resin layer 20b by electroless plating. By performing ultrasonic cleaning for 5 minutes or longer, the inorganic filler 22 deposited on the surface 21 of the insulating resin layer 20a can be reliably removed. By performing ultrasonic cleaning for 10 minutes or less, the cleaning solution (cleaner) components can be prevented from remaining on the insulating resin layer 20a, reducing the impact of residual cleaning solution on plating adhesion. Furthermore, if the immersion time in the cleaning solution is longer than 10 minutes, moisture in the cleaning solution may penetrate the insulating resin layer 20a, which may evaporate during annealing (heating) after plating, resulting in the formation of voids. However, a cleaning time of 10 minutes or less can prevent the formation of such voids.

[0045] In the method for manufacturing a semiconductor package according to this embodiment, the ultrasonic cleaning in the step of removing inorganic filler 22 may be performed during the electroless plating process in the step of forming plating layer 30. In this case, the removal of inorganic filler 22 and the formation of plating layer 30 can be performed partially in parallel, allowing for efficient processing.

[0046] Although the embodiments of the present disclosure have been described above, the present invention is not limited to the above-described embodiments, and appropriate modifications may be made without departing from the spirit of the present invention.

[0047] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0048] First, in Experimental Example 1, a film-like solder resist was attached to a substrate as an insulating resin layer. This solder resist contained epoxy resin, acrylic resin, elastomer, and inorganic filler. The inorganic filler content was 60% to 80% by mass. After hardening, the solder resist was irradiated with oxygen plasma for 5 minutes. The insulating resin layer that had undergone this plasma treatment was then subjected to electroless plating. This plating resulted in the formation of a plating layer by electroless plating over 54.5% of the surface area. In Experimental Example 1, at the end of the plasma treatment, the exposed area of ​​the inorganic filler contained in the entire surface (filler occupancy) was 47.9%. This value was calculated by binarization.

[0049] Next, in Experimental Example 2, the same material as in Experimental Example 1 was used and irradiated with oxygen plasma in the same manner. The type of plasma and irradiation conditions were the same as in Experimental Example 1. In Experimental Example 2, the insulating resin layer was further subjected to ultrasonic cleaning. The ultrasonic cleaning involved cleaning for 5 minutes using an aqueous solution containing a surfactant. The insulating resin layer that had undergone the plasma treatment and ultrasonic cleaning was then subjected to electroless plating. The plating conditions were the same as in Experimental Example 1. This resulted in the formation of a plating layer by electroless plating over 100% of the surface area. The average thickness of the plating layer was 300 nm. In Experimental Example 2, at the end of the ultrasonic cleaning, the exposed area of ​​the inorganic filler contained in the entire surface (filler occupancy) was 41.9%, which was a decrease in filler occupancy compared to the end of the plasma treatment (Experimental Example 1).

[0050] In Experimental Example 3, a different insulating resin material was used and irradiated with oxygen plasma in the same manner as in Experimental Example 1. The insulating resin material used in Experimental Example 3 contained, for example, an epoxy resin and an inorganic filler. The inorganic filler content was 60% by mass to 80% by mass. After curing this insulating resin material, it was irradiated with oxygen plasma for 5 minutes. Electroless plating was performed on the insulating resin layer that had undergone this plasma treatment. This plating resulted in the formation of a plating layer by electroless plating on 72.6% of the surface area. In Experimental Example 3, at the stage where the plasma treatment was completed, the exposed area of ​​the inorganic filler contained in the entire surface (filler occupancy) was 67.8%.

[0051] Next, in Experimental Example 4, the same material as in Experimental Example 3 was used and irradiated with oxygen plasma in the same manner. The type of plasma and irradiation conditions were the same as in Experimental Example 3. In Experimental Example 4, the insulating resin layer was further subjected to ultrasonic cleaning. The ultrasonic cleaning involved cleaning for 5 minutes using an aqueous solution containing a surfactant. The insulating resin layer that had undergone the plasma treatment and ultrasonic cleaning was then subjected to electroless plating. The plating conditions were the same as in Experimental Example 3. This resulted in the formation of a plating layer by electroless plating over 100% of the surface area. The average thickness of the plating layer was 300 nm. In Experimental Example 4, at the end of the ultrasonic cleaning, the exposed area of ​​the inorganic filler contained in the entire surface (filler occupancy) was 58.5%, which was a decrease in filler occupancy compared to the end of the plasma treatment (Experimental Example 3).

[0052] In Experimental Example 5, the same materials as in Experimental Example 1 were used, but the type of plasma was changed and argon (Ar) plasma was irradiated onto the surface of the solder resist. The insulating resin layer that had undergone this plasma treatment was then subjected to electroless plating. This resulted in the formation of a plating layer by electroless plating over several percent of the surface area.

[0053] As described above, the experimental examples confirmed that electroless plating can be reliably deposited on an insulating resin layer by activating the surface with plasma such as oxygen plasma and removing the inorganic filler particles from the surface by ultrasonic cleaning. Furthermore, electroless plating could also be deposited even when only plasma treatment was performed.

[0054] 10...substrate, 20, 20a, 20b...insulating resin layer, 21...surface, 22...inorganic filler, 30, 30a...plating layer, 40...electrode, 50...semiconductor element, 100...semiconductor package, P...plasma

Claims

1. A method for manufacturing a semiconductor package, comprising: a step of performing a surface treatment on a surface of an insulating resin layer on a substrate by irradiating the surface with oxygen plasma, wherein the insulating resin layer contains an inorganic filler; a step of removing at least a portion of the inorganic filler that has precipitated on the surface of the insulating resin layer; and a step of forming a plating layer by electroless plating on at least a portion of the surface of the insulating resin layer from which the inorganic filler has been removed.

2. A method for manufacturing a semiconductor package, comprising: a step of performing a surface treatment on a surface of an insulating resin layer on a substrate by irradiating the surface with plasma, the insulating resin layer containing an inorganic filler; a step of removing at least a portion of the inorganic filler precipitated on the surface of the insulating resin layer; and a step of forming a plating layer by electroless plating on at least a portion of the surface of the insulating resin layer from which the inorganic filler has been removed.

3. The method for manufacturing a semiconductor package according to claim 1 or 2, wherein the plasma irradiation time is 0.5 to 10 minutes.

4. A method for manufacturing a semiconductor package, comprising: a step of performing a surface treatment to activate the surface of an insulating resin layer on a substrate, the insulating resin layer containing an inorganic filler; a step of removing at least a portion of the inorganic filler that has precipitated on the surface of the insulating resin layer; and a step of forming a plating layer by electroless plating on at least a portion of the surface of the insulating resin layer from which the inorganic filler has been removed.

5. The method for manufacturing a semiconductor package according to any one of claims 1 to 4, wherein the resin composition forming the insulating resin layer contains an alkali-soluble resin.

6. The method for manufacturing a semiconductor package according to claim 4, wherein in the step of performing the surface treatment, a desmear treatment is performed on the insulating resin layer.

7. The method for manufacturing a semiconductor package according to any one of claims 1 to 6, wherein in the surface treatment step, at least one of a plasma treatment and a desmear treatment is repeated to give an uneven shape to the surface of the insulating resin layer and precipitate the inorganic filler.

8. The method for manufacturing a semiconductor package according to any one of claims 1 to 7, wherein in the step of removing the inorganic filler, ultrasonic cleaning is performed on the insulating resin layer.

9. The method for manufacturing a semiconductor package according to claim 8, wherein the ultrasonic cleaning in the step of removing the inorganic filler is performed during the electroless plating treatment in the step of forming the plating layer.

10. The method for manufacturing a semiconductor package according to claim 8 or 9, wherein the cleaning time by the ultrasonic cleaning is 5 to 10 minutes.

11. The method for manufacturing a semiconductor package according to any one of claims 1 to 8, wherein the step of forming the plating layer is carried out after the step of removing the inorganic filler.

12. A method for manufacturing a semiconductor package described in any one of claims 1 to 11, wherein the content of inorganic filler contained in the resin composition forming the insulating resin layer is 60 mass % to 80 mass % based on the total amount of solids contained in the insulating resin layer before curing.

13. The method for manufacturing a semiconductor package according to any one of claims 1 to 12, further comprising a step of forming the insulating resin layer by arranging a solder resist on a surface of the substrate which is a printed wiring board or a package substrate.

14. A method for manufacturing a semiconductor package as claimed in any one of claims 1 to 13, further comprising the steps of: after forming the plating layer, forming an electrode exposed outside the insulating resin layer using the plating layer as a seed layer; and mounting a semiconductor element provided with a terminal electrode on the insulating resin layer, connecting the electrode to the terminal electrode.

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