JP2022167400A - Method for forming re-wiring layer and method for manufacturing semiconductor package - Google Patents

Abstract

To make it possible to efficiently form a pattern including a fine via hole of an insulating resin film constituting a re-wiring layer by an imprint method.SOLUTION: There is provided a method for forming a re-wiring layer including an insulating resin film having a pattern including a via hole. The method includes a step of forming a pattern including the via hole in a thermosetting insulating resin film 2. The pattern including the via hole is formed by an imprint method including pushing a mold 3 against the insulating resin film 2 provided on a substrate 1, and drawing the mold 3 from the insulating resin film 2. The mold 3 is heated to a temperature higher than a reaction peak temperature of thermosetting reaction of the insulating resin film 2 while the mold 3 is pushed against the insulating resin film 2.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a method of forming a redistribution layer and a method of manufacturing a semiconductor package.

A semiconductor package such as a fan-out wafer level package (FOWLP) having a rewiring layer generally includes wiring connected to a semiconductor chip and a rewiring layer having an insulating resin film. is provided. The insulating resin film of the rewiring layer has a fine pattern including via holes for forming conductive vias that constitute wiring. A fine pattern of an insulating resin film may be formed by laser processing (for example, Patent Document 1).

JP 2013-058698 A

Pattern formation by imprinting using a mold is expected to be more advantageous than laser processing in terms of production efficiency and the like. However, when a pattern including fine via holes required in the insulating resin film constituting the rewiring layer is formed by imprinting, the mold pressed into the insulating resin film is separated from the insulating resin film, and then the insulating resin film is separated from the insulating resin film. It has been found that the formed pattern tends to disappear as the resin film is heated for curing. According to the method according to the present disclosure, a pattern including fine via holes in an insulating resin film that constitutes a rewiring layer can be efficiently formed by imprinting.

One aspect of the present disclosure relates to a method of forming a rewiring layer including an insulating resin film having a pattern including via holes, and a method of manufacturing a semiconductor package including forming the rewiring layer by the method. The method includes forming a pattern including via holes in a thermosetting insulating resin film. A pattern including the via holes is formed by an imprint method including pressing a mold into the insulating resin film provided on the substrate and pulling out the mold from the insulating resin film. While the mold is pressed against the insulating resin film, it is heated to a temperature higher than the reaction peak temperature of the thermosetting reaction of the insulating resin film.

According to one aspect of the present disclosure, a pattern including fine via holes in an insulating resin film that constitutes a rewiring layer can be efficiently formed by imprinting. According to some aspects of the present disclosure, a pattern including fine via holes in an insulating resin film can be formed in a shorter molding time.

4A to 4C are process diagrams showing an example of a method of forming an insulating resin film having a pattern including via holes; 4A to 4C are process diagrams showing an example of a method of forming an insulating resin film having a pattern including via holes; 4A to 4C are process diagrams showing an example of a method of forming an insulating resin film having a pattern including via holes; FIG. 4 is a plan view showing an example of a mold; FIG. 5 is a cross-sectional view taken along line VV of FIG. 4;

The invention is not limited to the following examples.

1, 2 and 3 are process diagrams showing an example of a method of forming an insulating resin film having a pattern including via holes. 1 to 3, a thermosetting insulating resin film 2 is provided on a substrate 1 (FIG. 1), and a mold 3 is pressed into the insulating resin film 2 provided on the substrate 1 (FIG. 2). ) and pulling out the mold 3 from the insulating resin film 2 to form the insulating resin film 2 (FIG. 3) having a pattern including the via holes 5 . The insulating resin film 2 is a film containing a thermosetting resin composition and may be non-photosensitive. While the mold 3 is pressed against the insulating resin film 2 , it is heated to a temperature higher than the reaction peak temperature of the thermosetting reaction of the insulating resin film 2 .

The substrate 1 may be an insulating substrate, examples of which include a glass substrate and a substrate containing a cured epoxy resin composition. The substrate 1 may be a sealing structure including a semiconductor chip (IC chip) and a sealing layer that seals the semiconductor chip. In that case, a rewiring layer including wiring to be connected to the connection terminals of the semiconductor chip may be formed.

The minimum melt viscosity of the insulating resin film 2 before the mold 3 is pushed may be 3000 Pa·s or more. When the minimum melt viscosity of the insulating resin film 2 is high, a stable pattern tends to be easily formed even if the time during which the mold 3 is pushed into the insulating resin film 2, that is, the molding time is short. From the same point of view, the minimum melt viscosity of the insulating resin film 2 is 3100 Pa·s or more, 3200 Pa·s or more, 3300 Pa·s or more, 3400 Pa·s or more, 3500 Pa·s or more, 3600 Pa·s or more, 3700 Pa·s or more, 3800 Pa · s or more, 3900 Pa·s or more, or 4000 Pa·s or more. The minimum melt viscosity of the insulating resin film 2 may be 8000 Pa·s or less, 7500 Pa·s or less, 7000 Pa·s or less, 6500 Pa·s or less, or 6000 Pa·s or less. Here, the minimum melt viscosity means the minimum value of the viscosity when the viscosity of a sample of the insulating resin film 2 is measured while increasing the temperature from 70° C. or lower at a temperature increase rate of 10° C./min. After showing the lowest melt viscosity, the viscosity of the insulating resin film 2 increases as the thermosetting reaction progresses.

The reaction peak temperature of the thermosetting reaction of the insulating resin film 2 may be 160° C. or lower. When the reaction peak temperature is low, a stable pattern tends to be easily formed even if the molding time is short. The reaction peak temperature may be 140° C. or higher, 145° C. or higher, or 150° C. or higher from the viewpoint of storage stability of the insulating resin film 2 . Here, the reaction peak temperature is the maximum amount of heat generated at the exothermic peak due to the curing reaction in a DSC thermogram obtained by differential scanning calorimetry under the condition that the temperature is increased from 30°C to 240°C at a temperature increase rate of 10°C/min. means the temperature at which

The insulating resin film 2 may contain a thermosetting resin, and may further contain a curing agent that reacts with the thermosetting resin. As will be understood by those skilled in the art, the reaction peak temperature of the insulating resin film 2 can be controlled based on the types of thermosetting resin and curing agent. The insulating resin film 2 may contain a polymer component having a weight average molecular weight of 10,000 or more. A part or all of the thermosetting resin may be a polymer component having a weight average molecular weight of 10,000 or more.

The thermosetting resin is a component that hardens the insulating resin film 2 by a thermosetting reaction, and examples thereof include epoxy resin and acrylic resin.

Epoxy resins are compounds having two or more epoxy groups, examples of which include bisphenol A type epoxy resins, bisphenol F type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, cresol novolak type epoxy resins, phenol Aralkyl-type epoxy resins, biphenyl-type epoxy resins, triphenylmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, and other polyfunctional epoxy resins can be mentioned. These can be used individually or in combination of 2 or more types.

Acrylic resins are compounds having one or more acryloyl groups, examples of which include bisphenol A type, bisphenol F type, naphthalene type, phenol novolak type, cresol novolak type, phenol aralkyl type, biphenyl type, and triphenylmethane type. , dicyclopentadiene-type, fluorene-type, adamantane-type, and other polyfunctional acrylic resins. These can be used individually or in combination of 2 or more types.

The acrylic resin may have 3 or less acrylic groups per molecule. When the number of acrylic groups is large, curing in a short time tends to be difficult to proceed sufficiently.

Thermosetting resins may be solid at room temperature (25° C.). The insulating resin film 2 containing a thermosetting resin that is solid at room temperature tends to suppress generation of voids and has a moderately low viscosity (tack) before curing.

The content of the thermosetting resin is, for example, 10 to 50 parts by mass with respect to 100 parts by mass of the insulating resin film 2 . When the content of the thermosetting resin is 10 to 50 parts by mass, the insulating resin film 2 tends to have an appropriate minimum melt viscosity. In addition, damage to the mold 3 due to excessive hardening of the insulating resin film 2 after curing can be suppressed.

Examples of curing agents for epoxy resins include phenol resin curing agents, acid anhydride curing agents, amine curing agents, imidazole curing agents, and phosphine curing agents.

Phenolic resin-based curing agents are compounds having two or more phenolic hydroxyl groups, examples of which include phenol novolak, cresol novolak, phenol aralkyl resins, cresol naphthol formaldehyde polycondensates, triphenylmethane-type polyfunctional phenols, and Other polyfunctional phenolic resins can be mentioned. These can be used individually or in combination of 2 or more types. The equivalent ratio of the phenolic resin-based curing agent to the epoxy resin (phenolic hydroxyl group/epoxy group, molar ratio) is 0.3 to 1.5, 0.4 from the viewpoint of good curability, adhesion and storage stability. ~1.0, or 0.5 to 1.0.

Examples of acid anhydride-based curing agents include methylcyclohexanetetracarboxylic dianhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, and ethylene glycol bisanhydrotrimellitate. These can be used individually or in combination of 2 or more types. The equivalent ratio of the acid anhydride-based curing agent to the epoxy resin (acid anhydride group/epoxy group, molar ratio) is 0.3 to 1.5, 0 from the viewpoint of good curability, adhesion and storage stability. .4 to 1.0, or 0.5 to 1.0.

Amine-based curing agents are compounds having an amino group, and examples thereof include dicyandiamide. The equivalent ratio (amino group/epoxy group, molar ratio) of the amine-based curing agent to the thermosetting resin is 0.3 to 1.5, 0.4 to 0.4 from the viewpoint of good curability, adhesion and storage stability. It may be 1.0, or 0.5 to 1.0.

The imidazole curing agent is a compound having an imidazole group, examples of which include 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole. , 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4- Diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine, 2,4-diamino-6-[2′-undecylimidazolyl-(1′)]-ethyl-s-triazine , 2,4-diamino-6-[2′-ethyl-4′-methylimidazolyl-(1′)]-ethyl-s-triazine, 2,4-diamino-6-[2′-methylimidazolyl-(1 ')]-ethyl-s-triazine isocyanurate, 2-phenylimidazole isocyanurate, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and , adducts of epoxy resins and imidazoles. From the viewpoint of excellent curability, storage stability and connection reliability, imidazole curing agents include 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, and 1-cyanoethyl-2-undecylimidazole. trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino- 6-[2′-ethyl-4′-methylimidazolyl-(1′)]-ethyl-s-triazine, 2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s - one or more selected from triazine isocyanurate adducts, 2-phenylimidazole isocyanurate adducts, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole; good too. The imidazole curing agent may be a microencapsulated latent curing agent. The content of the imidazole-based curing agent may be 0.1 to 20 parts by weight, or 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin, from the viewpoint of curability and adhesiveness.

Examples of phosphine curing agents include triphenylphosphine, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra(4-methylphenyl)borate and tetraphenylphosphonium(4-fluorophenyl)borate. The content of the phosphine-based curing agent may be 0.1 to 10 parts by mass, or 0.1 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin, from the viewpoint of curability.

From the viewpoint of handling, storage stability, and curability, the curing agent to be combined with the epoxy resin may be an imidazole curing agent alone. A combination with an acid anhydride curing agent or an amine curing agent may be used.

Examples of curing agents for acrylic resins include azo compounds and organic peroxides.

Examples of organic peroxides include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, and peroxyesters. From the viewpoint of storage stability, the organic peroxide may be hydroperoxide, dialkyl peroxide, or peroxyester. From the viewpoint of heat resistance, the organic peroxide may be hydroperoxide, dialkyl peroxide, or a combination thereof. These can be used individually or in combination of 2 or more types. The content of the organic peroxide may be 0.5 to 10% by mass, or 1 to 5% by mass based on the amount of the acrylic resin, from the viewpoint of curability.

The polymer component having a weight average molecular weight of 10,000 or more may be a thermosetting resin such as an epoxy resin, or may be a thermoplastic resin. Examples of polymeric components that are thermoplastic resins include phenoxy resins, polyimide resins, polyamide resins, polycarbodiimide resins, cyanate ester resins, acrylic resins, polyester resins, polyethylene resins, polyethersulfone resins, polyetherimide resins, polyvinyl Acetal resins, urethane resins, and acrylic rubbers are included. From the viewpoint of heat resistance and film formability, the polymer component may be an epoxy resin, a phenoxy resin, a polyimide resin, an acrylic resin, an acrylic rubber, a cyanate ester resin, a polycarbodiimide resin, or a combination thereof. Phenoxy resin, polyimide resin, acrylic resin, acrylic rubber, or a combination thereof may be used. The polymer components can be used singly or in combination of two or more. The weight average molecular weight can be a standard polystyrene-equivalent value determined by gel permeation chromatography.

The mass ratio of the epoxy resin having a weight average molecular weight of less than 10000 to the polymer component may be 0.01 to 5, 0.05 to 4, or 0.1 to 3 from the viewpoint of adhesion and film formation. good. The mass ratio of the acrylic resin having a weight average molecular weight of less than 10000 to the polymer component is 0.01 to 10, 0.05 to 5, or 0.1 to 5 from the viewpoint of adhesion and film formation. good too.

The insulating resin film 2 may contain filler. By introducing a filler, various physical properties can be controlled, and an insulating resin film 2 having an appropriate minimum melt viscosity tends to be easily formed. In addition, the filler can also contribute to suppression of void generation and moisture absorption. It is generally difficult to form a pattern of a photosensitive insulating resin film containing filler by photolithography. A fine pattern can be easily formed by

The filler can be an inorganic filler (particularly an insulating inorganic filler), a resinous filler, or a combination thereof. Examples of insulating inorganic fillers include glass, silica, alumina, titanium oxide, carbon black, mica, and boron nitride. The insulating inorganic filler may be silica, alumina, titanium oxide, boron nitride or a combination thereof, and may be silica, alumina, boron nitride or a combination thereof. Examples of resin fillers include polyurethanes, polyimides, methyl methacrylate resins, and methyl methacrylate-butadiene-styrene copolymer resins (MBS). The resin filler can impart flexibility to the insulating resin film 2 at high temperatures such as 260° C. compared to the inorganic filler, thereby contributing to improvement in film formability. Fillers can be whiskers such as aluminum borate, aluminum titanate, zinc oxide, calcium silicate, magnesium sulfate, and boron nitride. These fillers can be used singly or in combination of two or more. The insulating resin film 2 may not substantially contain conductive metal fillers such as silver fillers and solder fillers.

From the viewpoint of improving dispersibility and adhesive strength, the filler may be surface-treated. For example, the filler may be surface-treated with a glycidyl-based (epoxy-based), amine-based, phenyl-based, phenylamino-based, (meth)acrylic-based, or vinyl-based surface treating agent. A glycidyl-based, phenylamino-based, or (meth)acrylic-based surface treatment agent may be selected from the viewpoint of dispersibility, fluidity, and adhesive strength. From the viewpoint of storage stability, a phenyl, acrylic, or (meth)acrylic surface treatment agent may be selected. For ease of surface treatment, the surface treatment may be silane treatment using a surface treatment agent such as epoxysilane, aminosilane, or acrylsilane.

The average particle size of the filler may be 1.5 μm or less, or 1.0 μm or less.

The content of the filler is 30 to 90% by mass, or even 40 to 80% by mass, based on the mass of the insulating resin film 2, from the viewpoint of connection reliability, heat dissipation, void suppression, moisture absorption, etc. good.

The insulating resin film 2 is provided on the substrate 1 by, for example, applying a resin varnish containing a thermosetting resin composition and a solvent to the substrate 1 to form a coating film, and removing the solvent from the coating film. be done. Alternatively, the insulating resin film 2 may be provided on the substrate 1 by attaching an insulating resin film 2 formed in advance to the substrate 1 .

The resin varnish for forming the insulating resin film 2 contains a thermosetting resin composition containing a thermosetting resin and other necessary components, and an organic solvent. The resin varnish can be prepared by dissolving or dispersing the components constituting the thermosetting resin composition in an organic solvent by stirring, kneading, or the like.

When the insulating resin film 2 is formed in advance, the resin varnish is applied onto the base film that has been subjected to release treatment using a knife coater, roll coater, applicator, die coater, or comma coater, and the coating is heated. The insulating resin film 2 may be formed on the base film by a method of removing the organic solvent by . A resin varnish film may be formed by spin coating.

The substrate film may be, for example, a polyester film, a polypropylene film, a polyethylene terephthalate film, a polyimide film, a polyetherimide film, a polyethernaphthalate film, or a methylpentene film. The base film may be a single layer film or a multilayer film composed of two or more films.

The heating conditions for removing the organic solvent from the coating film of the resin varnish may be, for example, 50 to 200° C. for 0.1 to 90 minutes. The amount of the organic solvent remaining in the insulating resin film 2 may be 1.5 mass % or less based on the mass of the insulating resin film 2 .

The thickness of the insulating resin film 2 may be 4 to 10 μm. In general, the insulating resin film forming the rewiring layer is often required to have such a thickness. When the thickness of the insulating resin film 2 is 10 μm or less, after pattern formation by imprinting, the remaining resin film in the formed opening can be easily removed by a method such as plasma etching or laser abrasion. can be done. The thickness of the insulating resin film 2 usually substantially matches the height D of the via hole, which will be described later.

FIG. 4 is a plan view showing an example of the mold, and FIG. 5 is a cross-sectional view taken along line VV in FIG. The mold 3 shown in FIGS. 4 and 5 has a plurality of columnar projections 3A having a reverse shape of the via hole 5 formed in the insulating resin film 2. As shown in FIG. The mold 3 may be, for example, a molded body integrally formed of quartz glass, silicon, or nickel. The surface of the mold 3 may be subjected to release treatment. The method of the release treatment may be, for example, a method of spraying a release agent, or a method of coating the surface of the mold with a silane coupling agent or the like.

As shown in FIG. 2, the mold 3 is pushed into the insulating resin film 2 so that the projections 3A of the mold 3 are inserted into the insulating resin film 2. As shown in FIG. While pressed against the insulating resin film 2 , the mold 3 is heated to a predetermined temperature (molding temperature) higher than the reaction peak temperature of the insulating resin film 2 . The difference between the molding temperature and the reaction peak temperature may be, for example, 100°C or more. The molding temperature may be in the range of 150°C or higher and 300°C or lower. While the mold 3 is pressed against the insulating resin film 2 , the substrate 1 may be heated to a temperature that is the same as or different from the temperature of the mold 3 . The temperature of substrate 1 may be lower than the temperature of mold 3 .

The time (molding time) during which the mold 3 is pushed into the insulating resin film 2 may be, for example, 300 seconds or less, 240 seconds or less, 180 seconds or less, or 120 seconds or less, or 60 seconds or less, or 5 seconds or more. , or 10 seconds or longer.

The force for pressing the mold 3 against the insulating resin film 2 is set within a range that sufficiently suppresses damage to the projections 3A.

Subsequently, as shown in FIG. 3, the mold 3 is pulled out from the insulating resin film 2, thereby forming the insulating resin film 2 having a pattern including via holes 5 having an inverted shape of the projections 3A. The mold 3 may be pulled out from the insulating resin film 2 after the temperatures of the mold 3 and the substrate 1 are lowered to room temperature (for example, 20 to 30° C.).

After the mold 3 is pulled out, the insulating resin film 2 may be further heated. This heating further advances the curing reaction of the insulating resin film 2 . The heating temperature may be, for example, 180-200° C., and the heating time may be, for example, 60-120 minutes.

After the mold 3 is pulled out, the insulating resin film may remain on the bottom of the via hole 5 . Therefore, the method of forming the rewiring layer may further include removing the insulating resin film remaining on the bottom of the via hole 5 . The imprinting conditions may be optimized so that the thickness of the remaining insulating resin film is 1 μm or less. A method for removing the remaining insulating resin film may be, for example, plasma processing or laser processing. In the case of plasma processing, the remaining insulating resin film can be removed while suppressing damage to the via holes by adjusting the gas and output to be used. For example, plasma treatment using oxygen gas and fluoroform gas can be employed.

The via hole 5 can be a through hole with maximum width W and height D. FIG. The ratio of the height D of the via hole 5 to the maximum width W of the via hole 5 (hereinafter sometimes referred to as "aspect ratio") is 3.0 or more, 4.0 or more, 5.0 or more, or 6.0 or more may be Although the upper limit of the aspect ratio is not particularly limited, it is usually about 15. According to the method according to one aspect of the present disclosure, a via hole having a large aspect ratio can be stably and efficiently formed while suppressing damage to the mold. The maximum width W of the via hole 5 may be 5.0 μm or less, 4.0 μm or less, 3.0 μm or less, 2.0 μm or less, or 0.1 μm or more. The height D of the via hole 5 may be 2.0 μm or more, 3.0 μm or more, 4.0 μm or more, 5.0 μm or more, 6.0 μm or more, or 7.0 μm or more, and may be 20 μm or less. good too.

The method of forming the redistribution layer may further comprise forming a metal layer including conductive vias filling the via hole 5 and a wiring layer. The rewiring layer including the insulating resin film and the metal layer covers, for example, the insulating resin film 2 to form a seed layer used as a power feeding layer for plating, forming a metal plating layer on the seed layer, removing a portion of the metal layer and the insulating resin film from the side opposite to the substrate 1 to form a flat surface where the metal layer and the insulating resin film are exposed. The seed layer is a layer formed by sputtering, for example. A metal plating layer is formed on the seed layer. The metal plating layer may be a plating layer containing copper.

A flat surface is formed by planarizing the metal layer and the insulating resin layer. A chemical mechanical polishing apparatus or a mechanical polishing apparatus may be used for planar polishing. The method of removing the metal layer may be immersion in an etchant.

An additional non-photosensitive insulating resin layer is formed on the flat surface, and a pattern including a via hole penetrating the additional insulating resin film and a portion having an inverted shape of the groove for forming the additional wiring layer is formed. One or more layers of additional insulation are formed by repeating the steps of forming an additional insulating resin film by a printing method and forming an additional conductive via filling the via hole and an additional wiring layer filling the trench. A resin layer, additional conductive vias through each additional insulating resin layer, and additional wiring layers connected to the additional conductive vias can be formed, thereby forming a multi-layer redistribution layer. .

The rewiring layer formed by the method including the steps illustrated above is used as a rewiring layer connected to a semiconductor chip in a semiconductor package such as a fan-out type wafer level package (FOWLP).

The invention is not limited to the following examples.

1. Insulating resin film A thermosetting epoxy resin composition was prepared by mixing the raw materials shown below in the amounts (parts by mass) shown in Table 1, and using this, a non-photosensitive insulating resin film (thickness: 8 μm) was formed on the support film.
(i) Phenoxy resin (polymer component)
・FX293 (trade name, weight average molecular weight: about 63000, Nippon Steel Chemical & Materials Co., Ltd.)
(ii) Epoxy resin EP1032H60 (trade name, solid polyfunctional epoxy resin containing a triphenolmethane skeleton, weight average molecular weight: 800 to 2000, Mitsubishi Chemical & Materials Co., Ltd.)
・YL983U (trade name, bisphenol F mold liquid epoxy resin, molecular weight: about 336, Mitsubishi Chemical & Materials Co., Ltd.)
・YX7110B80 (special semi-solid epoxy resin, Mitsubishi Chemical & Materials Co., Ltd.)
(iii) Curing agent 2MAOK-PW (trade name, 2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine isocyanurate adduct, Shikoku Kasei Co., Ltd.)
(iv) Filler resin filler EXL2655 (core-shell type organic filler, Rohm and Haas Japan Co., Ltd.)
Inorganic filler SE2030 (trade name, silica filler, Admatechs Co., Ltd., average particle size: 0.5 μm)
・ SE2030-SEJ (trade name, silica filler surface-treated with epoxysilane, Admatechs Co., Ltd., average particle size: 0.5 μm)
・ YA050C-HGF (trade name, nano silica filler whose surface is treated with epoxysilane, Admatechs Co., Ltd., average particle size: about 50 nm)

2. Evaluation (1) Reaction Peak Temperature A 5-10 mg sample taken from each insulating resin film was placed in an aluminum pan for differential scanning calorimetry (DSC). Using a differential scanning calorimeter (DSC-7, manufactured by PerkinElmer), a DSC thermogram was obtained by measuring conditions in which the temperature was raised from 30°C to 240°C at a heating rate of 10°C/min. In the DSC thermogram, the reaction peak temperature was defined as the temperature at which the amount of heat generated in the exothermic peak due to the curing reaction reached its maximum.

(2) Minimum Melt Viscosity A plurality of insulating resin films were laminated while being heated to 85° C. using a laminator (HOT DOG, manufactured by Rami Corporation) to form a sample with a thickness of 200 to 300 μm. The formed sample was supplied onto a stage for viscosity measurement, and the viscoelasticity of the sample was measured while the temperature was raised from 70°C to 240°C using a rheometer (TA Instruments, ARES-G2). The viscoelasticity measurement conditions were a swing angle of 1%, a frequency of 10 Hz, and a heating rate of 10° C./min. In the curve showing the relationship between viscosity (complex viscosity) and temperature, the lowest value of viscosity was taken as the lowest melt viscosity.

(3) Pattern Formation Test by Imprint Method The insulating resin film was attached to a silicon wafer (5 cm square, 780 mm thick) while heating to 85° C. using a laminator (HOT DOG, Rami Corporation).
A silicon molded body having a plurality of cylindrical protrusions with a diameter of 1 μm and a height of 8 μm was prepared as a mold. This mold was attached to a pressure head, and while the mold was heated to 280° C. by the pressure head, the mold was applied to the insulating resin film attached to the silicon wafer by a flip chip bonder (FC3000W manufactured by Toray Engineering Co., Ltd.). It was pushed on a stage heated to 120° C. so that the protrusions were inserted. A load of 70 N was applied to the mold for indentation. After 30 seconds had passed since the mold was pushed in, the mold was pulled out from the insulating resin film. In the insulating resin film after the mold was pulled out, it was confirmed that a via having a reverse shape of the projection was formed.

Shape Retainability Surfaces of vias formed by imprinting were observed with a digital microscope (manufactured by Keyence Corporation, VHX-5000) to determine via diameters. Thereafter, the insulating resin film having vias was heat-treated at 190° C. for 2 hours in an oven (HT210, manufactured by ETAC). Gold, platinum, and palladium were vapor-deposited on the heat-treated insulating resin film using a vapor deposition apparatus (MSP-1S, manufactured by Vacuum Device Co., Ltd.) for about 2 minutes. A cross-section of the insulating resin film after vapor deposition was observed using an FE-SEM (Regulus 8230, manufactured by Hitachi High-Tech) to determine the diameter of the via. If the diameter of the via after heat treatment is more than half the diameter of the via before heat treatment, it is evaluated as "OK". A small case was evaluated as "NG".

Evaluation results are shown in Table 1. It was confirmed that a fine pattern including vias with excellent stability can be formed in a short molding time by imprinting under conditions where the heating temperature (molding temperature) of the mold is higher than the reaction peak temperature of the insulating resin film.

DESCRIPTION OF SYMBOLS 1... Substrate 2... Insulating resin film 3... Mold 3A... Convex portion 5... Via hole W: Width of via hole D: Height of via hole.

Claims (9)

A method for forming a rewiring layer including an insulating resin film having a pattern including via holes, comprising:
The method includes forming a pattern including via holes in a thermosetting insulating resin film,
the pattern including the via hole is formed by an imprint method including pressing a mold into the insulating resin film provided on the substrate and pulling out the mold from the insulating resin film;
The method, wherein the mold is heated to a temperature higher than a reaction peak temperature of a thermosetting reaction of the insulating resin film while the mold is pressed against the insulating resin film. The method includes forming a coating film by applying a resin varnish containing a thermosetting resin composition and a solvent to the substrate, and removing the solvent from the coating film to form the insulating resin film on the substrate. 2. The method of claim 1, further comprising providing. 2. The method of claim 1, wherein the method further comprises providing the insulating resin film on the substrate by affixing the pre-formed insulating resin film to the substrate. The method according to any one of claims 1 to 3, wherein the insulating resin film has a minimum melt viscosity of 3000 Pa·s or more. The method according to any one of claims 1 to 4, wherein the reaction peak temperature is 160°C or less. The method according to any one of claims 1 to 5, wherein the insulating resin film contains filler. The method according to any one of claims 1 to 6, wherein the ratio of the height of said via hole to said maximum width of said via hole is 3.0 or more. The method according to any one of claims 1 to 7, wherein the maximum width of said via hole is 5.0 µm or less. A method of manufacturing a semiconductor package, comprising forming a rewiring layer by the method according to any one of claims 1-8.

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