Method for forming rewiring layer and method for manufacturing semiconductor package

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

[Technical Field]

[0001] The present disclosure relates to a method for forming a redistribution layer and a method for manufacturing a semiconductor package. [Background technology]

[0002] A semiconductor package such as a fan-out wafer level package (FOWLP) having a rewiring layer is generally provided with a rewiring layer having wiring connected to a semiconductor chip and an insulating resin film. The insulating resin film of the rewiring layer has a fine pattern including via holes for forming conductive vias that constitute the wiring. The fine pattern of the insulating resin film is sometimes formed by laser processing (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-058698 Summary of the Invention [Problem to be solved by the invention]

[0004] Pattern formation using a mold by imprinting is expected to be more advantageous than laser processing in terms of production efficiency, etc. However, when a pattern including fine via holes required in an insulating resin film constituting a redistribution layer is formed by imprinting, it has been found that after the mold pressed into the insulating resin film is separated from the insulating resin film, the formed pattern is likely to disappear as the insulating resin film is heated to harden. According to the method disclosed herein, a pattern including fine via holes in an insulating resin film constituting a redistribution layer can be efficiently formed by imprinting. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a method for forming a redistribution layer including an insulating resin film having a pattern including via holes, and a method for manufacturing a semiconductor package including forming a redistribution layer by the method. The method includes forming a pattern including via holes in a thermosetting insulating resin film. The pattern including the via holes is formed by an imprint method including pressing a mold into the insulating resin film provided on a substrate and pulling the mold out of the insulating resin film. While the mold is being pressed into the insulating resin film, the insulating resin film is heated to a temperature higher than the reaction peak temperature of the thermosetting reaction of the insulating resin film.

Advantages of the Invention

[0006] According to one aspect of the present disclosure, a pattern including fine via holes in an insulating resin film constituting a redistribution layer can be efficiently formed by an imprint method. 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.

Brief Description of the Drawings

[0007] [Figure 1] It is a process diagram showing an example of a method for forming an insulating resin film having a pattern including via holes. [Figure 2] It is a process diagram showing an example of a method for forming an insulating resin film having a pattern including via holes. [Figure 3] It is a process diagram showing an example of a method for forming an insulating resin film having a pattern including via holes. [Figure 4] It is a plan view showing an example of a mold. [Figure 5] It is a cross-sectional view taken along the line V-V of FIG. 4.

Embodiments for Carrying Out the Invention

[0008] The present invention is not limited to the following examples.

[0009] FIG. 1, FIG. 2, and FIG. 3 are process diagrams showing an example of a method for forming an insulating resin film having a pattern including via holes. FIGS. 1 to 3 include providing a thermosetting insulating resin film 2 on a substrate 1 (FIG. 1), pressing a mold 3 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. By an imprint method, an insulating resin film 2 (FIG. 3) having a pattern including via holes 5 is formed. The insulating resin film 2 is a film containing a thermosetting resin composition and may be non-photosensitive. The mold 3 is heated to a temperature higher than the reaction peak temperature of the thermosetting reaction of the insulating resin film 2 while being pressed into the insulating resin film 2.

[0010] The substrate 1 may be an insulating substrate, and examples thereof include a glass substrate and a substrate including a cured body of an epoxy resin composition. The substrate 1 may be a sealing structure including a semiconductor chip (IC chip) and a sealing layer for sealing the semiconductor chip. In that case, a redistribution layer including wiring connected to the connection terminals of the semiconductor chip may be formed.

[0011] The minimum melt viscosity of the insulating resin film 2 before the mold 3 is pressed in may be 3000 Pa·s or more. When the minimum melt viscosity of the insulating resin film 2 is high, even if the time for which the mold 3 is pressed into the insulating resin film 2, that is, the molding time, is short, a stable pattern tends to be easily formed. From the same viewpoint, the minimum melt viscosity of the insulating resin film 2 may be 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 heating from a temperature of 70°C or lower at a heating rate of 10°C / min. The viscosity of the insulating resin film 2 increases as the thermosetting reaction progresses after showing the minimum melt viscosity.

[0012] 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, even if the molding time is short, a stable pattern tends to be easily formed. The reaction peak temperature may be 140°C or higher, 145°C or higher, or 150°C or higher from the viewpoint of the storage stability of the insulating resin film 2. Here, the reaction peak temperature means the temperature at the point where the heat generation amount is maximum in the exothermic peak due to the curing reaction in the DSC thermogram obtained by differential scanning calorimetry under the condition of raising the temperature from 30°C to 240°C at a heating rate of 10°C / min.

[0013] 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, based on the types of the thermosetting resin and the curing agent, etc., the reaction peak temperature of the insulating resin film 2 can be controlled. The insulating resin film 2 may contain a polymer component having a weight average molecular weight of 10,000 or more. Part or all of the thermosetting resin may be a polymer component having a weight average molecular weight of 10,000 or more.

[0014] The thermosetting resin is a component that cures the insulating resin film 2 by a thermosetting reaction, and examples thereof include epoxy resins and acrylic resins.

[0015] The epoxy resin is a compound having two or more epoxy groups, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, and other polyfunctional epoxy resins. These can be used alone or in combination of two or more.

[0016] The acrylic resin is a compound having one or more acryloyl groups, and examples thereof include bisphenol A type, bisphenol F type, naphthalene type, phenol novolak type, cresol novolak type, phenol aralkyl type, biphenyl type, triphenylmethane type, dicyclopentadiene type, fluorene type, adamantane type, and other polyfunctional acrylic resins. These can be used alone or in combination of two or more.

[0017] The number of acrylic groups in the acrylic resin may be 3 or less per molecule. When the number of acrylic groups is large, curing tends not to proceed sufficiently in a short time.

[0018] The thermosetting resin 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 the generation of voids and has an appropriately small viscosity (tack) before curing.

[0019] The content of the thermosetting resin is, for example, 10 to 50 parts by mass with respect to 100 parts by mass of the 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 is likely to have an appropriate minimum melt viscosity. In addition, damage to the mold 3 due to the insulating resin film 2 being too hard after curing can be suppressed.

[0020] Examples of the curing agent for the epoxy resin include phenolic resin-based curing agents, acid anhydride-based curing agents, amine-based curing agents, imidazole-based curing agents, and phosphine-based curing agents.

[0021] The phenolic resin curing agent is a compound having two or more phenolic hydroxyl groups, and examples thereof include phenol novolac, cresol novolac, phenol aralkyl resin, cresol naphthol formaldehyde polycondensate, triphenylmethane type polyfunctional phenol, and other polyfunctional phenolic resins. These can be used alone or in combination of two or more. The equivalent ratio (phenolic hydroxyl group / epoxy group, molar ratio) of the phenolic resin curing agent to the epoxy resin may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0 from the viewpoints of good curability, adhesiveness, and storage stability.

[0022] Examples of the acid anhydride curing agent include methylcyclohexane tetracarboxylic dianhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, and ethylene glycol bisanhydrotrimellitate. These can be used alone or in combination of two or more. The equivalent ratio (acid anhydride group / epoxy group, molar ratio) of the acid anhydride curing agent to the epoxy resin may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0 from the viewpoints of good curability, adhesiveness, and storage stability.

[0023] The amine curing agent is a compound having an amino group, and an example thereof is dicyandiamide. The equivalent ratio (amino group / epoxy group, molar ratio) of the amine curing agent to the thermosetting resin may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0 from the viewpoints of good curability, adhesiveness, and storage stability.

[0024] Imidazole-based curing agents are compounds having an imidazole group. Examples thereof 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 isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and adducts of epoxy resins and imidazoles. From the viewpoints of excellent curability, storage stability, and connection reliability, the imidazole-based curing agent may be one or more selected from 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'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. The imidazole-based curing agent may be a microencapsulated latent curing agent.From the viewpoints of curability and adhesiveness, etc., the content of the imidazole-based curing agent may be 0.1 to 20 parts by mass, or 0.1 to 10 parts by mass, based on 100 parts by mass of the epoxy resin.

[0025] Examples of the phosphine-based curing agent include triphenylphosphine, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra(4-methylphenyl)borate, and tetraphenylphosphonium (4-fluorophenyl)borate. From the viewpoint of curability, etc., 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, based on 100 parts by mass of the epoxy resin.

[0026] From the viewpoints of handleability, storage stability, and curability, the curing agent combined with the epoxy resin may be an imidazole-based curing agent alone, or a combination of an imidazole-based curing agent and a phosphine-based curing agent with a phenolic resin-based curing agent, an acid anhydride-based curing agent, or an amine-based curing agent.

[0027] Examples of the curing agent for the acrylic resin include azo compounds and organic peroxides.

[0028] Examples of the organic peroxide include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, and peroxyester. From the viewpoint of storage stability, the organic peroxide may be a hydroperoxide, a dialkyl peroxide, or a peroxyester. From the viewpoint of heat resistance, the organic peroxide may be a hydroperoxide, a dialkyl peroxide, or a combination thereof. These can be used alone or in combination of two or more. From the viewpoint of curability, etc., 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.

[0029] 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 a thermoplastic resin. Examples of the polymer component that is a thermoplastic resin include phenoxy resin, polyimide resin, polyamide resin, polycarbodiimide resin, cyanate ester resin, acrylic resin, polyester resin, polyethylene resin, polyethersulfone resin, polyetherimide resin, polyvinyl acetal resin, urethane resin, and acrylic rubber. From the viewpoints of heat resistance and film-forming property, the polymer component may be an epoxy resin, phenoxy resin, polyimide resin, acrylic resin, acrylic rubber, cyanate ester resin, polycarbodiimide resin, or a combination thereof, or may be an epoxy resin, phenoxy resin, polyimide resin, acrylic resin, acrylic rubber, or a combination thereof. The polymer component can be used alone or in a combination of two or more. The weight average molecular weight can be a value in terms of standard polystyrene determined by gel permeation chromatography method.

[0030] The mass ratio of the epoxy resin having a weight average molecular weight of less than 10,000 to the polymer component may be 0.01 to 5, 0.05 to 4, or 0.1 to 3 from the viewpoints of adhesiveness and film formation. The mass ratio of the acrylic resin having a weight average molecular weight of less than 10,000 to the polymer component may be 0.01 to 10, 0.05 to 5, or 0.1 to 5 from the viewpoints of adhesiveness and film-forming property.

[0031] The insulating resin film 2 may contain a filler. By introducing the filler, various physical properties can be controlled, and an insulating resin film 2 having an appropriate minimum melt viscosity tends to be easily formed. Also, the filler can contribute to the suppression of void generation and moisture absorption rate. Although it is generally difficult to form a pattern of a photosensitive insulating resin film containing a filler by photolithography, in the case of a thermosetting insulating resin film, even if it contains a filler, a fine pattern can be easily formed by an imprint method.

[0032] The filler can be an inorganic filler (especially an insulating inorganic filler), a resin filler, or a combination thereof. Examples of the insulating inorganic filler 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, or may be silica, alumina, boron nitride, or a combination thereof. Examples of the resin filler include polyurethane, polyimide, methyl methacrylate resin, and methyl methacrylate-butadiene-styrene copolymer resin (MBS). The resin filler can impart flexibility at a high temperature such as 260°C to the insulating resin film 2 compared to the inorganic filler, thereby contributing to the improvement of film formability. The filler may be a whisker such as aluminum borate, aluminum titanate, zinc oxide, calcium silicate, magnesium sulfate, and boron nitride. These fillers can be used alone or in combination of two or more. The insulating resin film 2 may not substantially contain a conductive metal filler such as a silver filler and a solder filler.

[0033] From the viewpoints of improving dispersibility and adhesion, 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 treatment agent. From the viewpoints of dispersibility, fluidity, and adhesion, a glycidyl-based, phenylamino-based, or (meth)acrylic-based surface treatment agent may be selected. From the viewpoint of storage stability, a phenyl-based, acrylic-based, or (meth)acrylic-based surface treatment agent may be selected. From the ease of surface treatment, the surface treatment may be a silane treatment using a surface treatment agent such as an epoxy silane-based, amino silane-based, or acrylic silane-based surface treatment agent.

[0034] The average particle size of the filler may be 1.5 μm or less, or 1.0 μm or less.

[0035] The content of the filler may be 30 to 90% by mass, or 40 to 80% by mass, based on the mass of the insulating resin film 2, from the viewpoints of connection reliability, heat dissipation, void suppression, moisture absorption rate, and the like.

[0036] The insulating resin film 2 is provided on the substrate 1, for example, by forming a coating film by applying a resin varnish containing a thermosetting resin composition and a solvent to the substrate 1, and removing the solvent from the coating film. Alternatively, the insulating resin film 2 may be provided on the substrate 1 by attaching a pre-formed insulating resin film 2 to the substrate 1.

[0037] 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 and kneading.

[0038] When the insulating resin film 2 is pre-formed, the resin varnish may be applied onto a base film subjected to a release treatment using a knife coater, a roll coater, an applicator, a die coater, or a comma coater, and the insulating resin film 2 may be formed on the base film by a method of removing the organic solvent from the coating film by heating. A film of the resin varnish may be formed by spin coating.

[0039] The base film may be, for example, a polyester film, a polypropylene film, a polyethylene terephthalate film, a polyimide film, a polyetherimide film, a polyether naphthalate film, or a methylpentene film. The base film may be a single-layer film or a multilayer film composed of two or more films.

[0040] 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% by mass or less based on the mass of the insulating resin film 2.

[0041] The thickness of the insulating resin film 2 may be 4 to 10 μm. Generally, the insulating resin film constituting the rewiring layer often needs to have such a thickness. When the thickness of the insulating resin film 2 is 10 μm or less, after pattern formation by the imprint method, the remaining film of the resin in the formed opening can be easily removed by a method such as plasma etching or laser ablation. The thickness of the insulating resin film 2 generally substantially coincides with the height D of the via hole described later.

[0042] FIG. 4 is a plan view showing an example of a mold, and FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4. The mold 3 shown in FIGS. 4 and 5 has a plurality of columnar convex portions 3A including an inverted shape of the via hole 5 formed in the insulating resin film 2. 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 a release treatment. The method of the release treatment may be, for example, a method of spraying a release agent or the like, or a method of coating the surface of the mold with a silane coupling agent or the like.

[0043] As shown in FIG. 2, the mold 3 is pushed into the insulating resin film 2 so that its convex portion 3A is inserted into the insulating resin film 2. While being pushed into 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 more and 300 ° C or less. While the mold 3 is being pushed into the insulating resin film 2, the substrate 1 may be heated to the same or different temperature as the temperature of the mold 3. The temperature of the substrate 1 may be lower than the temperature of the mold 3.

[0044] The time (molding time) for 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, and may also be 5 seconds or more, or 10 seconds or more.

[0045] The force for pressing the mold 3 into the insulating resin film 2 is set within a range where damage to the convex portion 3A is sufficiently suppressed.

[0046] Subsequently, as shown in FIG. 3, the mold 3 is pulled out from the insulating resin film 2, whereby an insulating resin film 2 having a pattern including via holes 5 having an inverted shape of the convex portion 3A is formed. The mold 3 may be pulled out from the insulating resin film 2 after the temperatures of the mold 3 and the substrate 1 have dropped to room temperature (for example, 20 to 30°C).

[0047] After the mold 3 is pulled out, the insulating resin film 2 may be further heated. By this heating, the curing reaction of the insulating resin film 2 further proceeds. The heating temperature may be, for example, 180 to 200°C, and the heating time may be, for example, 60 to 120 minutes.

[0048] After the mold 3 is pulled out, an insulating resin film may remain at the bottom of the via hole 5. Therefore, the method for forming the rewiring layer may further include removing the insulating resin film remaining at the bottom of the via hole 5. The conditions of the imprint method may be optimized so that the thickness of the remaining insulating resin film becomes 1 μm or less. The method for removing the remaining insulating resin film may be, for example, plasma treatment or laser processing. In the case of plasma treatment, by adjusting the gas used, the output, etc., the remaining insulating resin film can be removed while suppressing damage to the via holes. For example, plasma treatment using oxygen gas and fluorohorm gas can be employed.

[0049] The via hole 5 can be a through hole having a maximum width W and a height D. 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 the "aspect ratio") may be 3.0 or more, 4.0 or more, 5.0 or more, or 6.0 or more. The upper limit of the aspect ratio is not particularly limited, but 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, or 2.0 μm or less, and may be 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.

[0050] The method of forming the rewiring layer may further include forming a metal layer including a conductive via filling the via hole 5 and a wiring layer. The rewiring layer including the insulating resin film and the metal layer is formed, for example, by covering the insulating resin film 2 and forming a seed layer used as a power feeding layer for plating, forming a metal plating layer on the seed layer, and removing a part of the metal layer and the insulating resin film from the side opposite to the substrate 1 to form a flat surface on which the metal layer and the insulating resin film are exposed. The seed layer is a layer formed, for example, by a sputtering method. A metal plating layer is formed on the seed layer. The metal plating layer may be a plating layer containing copper.

[0051] A flat surface is formed by planar polishing the metal layer and the insulating resin layer. For planar polishing, a chemical mechanical polishing apparatus or a mechanical polishing apparatus may be used. The method of removing the metal layer may be immersion in an etching solution.

[0052] By repeating the steps of forming an additional non-photosensitive insulating resin layer on a flat surface, forming a pattern in the additional insulating resin film by an imprinting method, the pattern including via holes penetrating the additional insulating resin film and portions having the inverted shape of the grooves for forming additional wiring layers, and forming additional conductive vias that fill the via holes and additional wiring layers that fill the grooves, it is possible to form one or more additional insulating resin layers, additional conductive vias that penetrate each of the additional insulating resin layers, and additional wiring layers connected to the additional conductive vias, thereby forming a multi-layer rewiring layer.

[0053] The rewiring layer formed by the method including the steps exemplified above is used as a rewiring layer connected to a semiconductor chip in a semiconductor package such as a fan-out wafer level package (FOWLP). [Example]

[0054] The present invention is not limited to the following examples.

[0055] 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 a non-photosensitive insulating resin film (thickness: 8 μm) was formed on a support film using this composition. (i) Phenoxy resin (polymer component) FX293 (product name, weight average molecular weight: approximately 63,000, Nippon Steel Chemical & Material Co., Ltd.) (ii) Epoxy resin EP1032H60 (product name, solid multifunctional epoxy resin containing triphenolmethane skeleton, weight average molecular weight: 800-2000, Mitsubishi Chemical & Materials Corporation) YL983U (product name, bisphenol F mold liquid epoxy resin, molecular weight: approximately 336, Mitsubishi Chemical & Materials Corporation) YX7110B80 (special semi-solid epoxy resin, Mitsubishi Chemical & Materials Corporation) (iii) hardener · 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 epoxy silane, Admatechs Co., Ltd., average particle size: 0.5 μm) · YA050C-HGF (trade name, nanosilica filler surface-treated with epoxy silane, Admatechs Co., Ltd., average particle size: about 50 nm)

[0056] 2. Evaluation (1) Reaction peak temperature Samples of 5 - 10 mg taken from each insulating resin film were placed in an aluminum pan for differential scanning calorimetry (DSC). Using a differential scanning calorimeter (PerkinElmer, DSC-7), a DSC thermogram was obtained by measuring under the condition of heating from 30 °C to 240 °C at a heating rate of 10 °C / min. In the DSC thermogram, the temperature at the point where the heat generation amount was maximum at the exothermic peak due to the curing reaction was defined as the reaction peak temperature.

[0057] (2) Minimum melt viscosity Each insulating resin film was laminated in multiple layers while heating to 85 °C using a laminator (manufactured by Lamicorporation, HOT DOG) to form a sample with a thickness of 200 - 300 μm. The formed sample was supplied onto a stage for viscosity measurement, and the viscoelasticity of the sample was measured using a rheometer (TA Instruments, ARES-G2) while heating from 70 °C to 240 °C. The measurement conditions for viscoelasticity were an oscillation 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 minimum value of viscosity was defined as the minimum melt viscosity.

[0058] (3) Pattern formation test by imprint method An insulating resin film was attached to a silicon wafer (5 cm square, 780 mm thick) while heating it to 85 °C using a laminator (Lamico Corporation, HOT DOG). A silicon mold having a plurality of cylindrical protrusions with a diameter of 1 μm and a height of 8 μm was prepared. This mold was attached to a pressure head, and while heating the mold to 280 °C with the pressure head, the mold was pressed against the insulating resin film attached to the silicon wafer on a stage heated to 120 °C by a flip chip bonder (manufactured by Toray Engineering, FC3000W) so that the protrusions were inserted. A load of 70 N was applied to the mold for pressing. When 30 seconds had elapsed after the mold was pressed in, the mold was pulled out from the insulating resin film. It was confirmed that vias having an inverted shape of the protrusions were formed in the insulating resin film after the mold was pulled out.

[0059] Shape retention The surface of the via formed by the imprint method was observed with a digital microscope (manufactured by Keyence, VHX-5000) to determine the diameter of the via. Then, the insulating resin film having the via was heat-treated in an oven (manufactured by ETAC, HT210) at 190 °C for 2 hours. Gold, platinum, and palladium were deposited on the heat-treated insulating resin film using a vapor deposition apparatus (manufactured by Vacuum Device, MSP-1S) over about 2 minutes. The cross-section of the insulating resin film after deposition was observed using an FE-SEM (manufactured by Hitachi High-Tech, Regulus8230) to determine the diameter of the via. When the diameter of the via after heat treatment was half or more of the diameter of the via before heat treatment, it was evaluated as "OK", and when the diameter of the via after heat treatment was less than half of the diameter of the via before heat treatment, it was evaluated as "NG".

[0060]

Table 1

[0061] The evaluation results are shown in Table 1. It was confirmed that by the imprint method under the condition that the heating temperature (molding temperature) of the mold is higher than the reaction peak temperature of the insulating resin film, a fine pattern including vias with excellent stability can be formed in a short molding time.

Explanation of symbols

[0062] 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

1. A method for forming a rewiring layer including an insulating resin film having a pattern including via holes, comprising: forming a pattern including via holes in a thermosetting insulating resin film, wherein the pattern including the via holes is formed by an imprint method including pressing a mold into the insulating resin film provided on a substrate and pulling the mold out of the insulating resin film, wherein the mold is heated to a molding temperature higher than the reaction peak temperature of the thermosetting reaction of the insulating resin film while being pressed into the insulating resin film, the method further comprising forming a coating film by applying a resin varnish including a thermosetting resin composition and a solvent to the substrate, and providing the insulating resin film on the substrate by removing the solvent from the coating film.

2. A method for forming a rewiring layer including an insulating resin film having a pattern including via holes, comprising: forming a pattern including via holes in a thermosetting insulating resin film, wherein the pattern including the via holes is formed by an imprint method including pressing a mold into the insulating resin film provided on a substrate and pulling the mold out of the insulating resin film, wherein the mold is heated to a molding temperature higher than the reaction peak temperature of the thermosetting reaction of the insulating resin film while being pressed into the insulating resin film, the method further comprising providing the insulating resin film on the substrate by attaching the pre-formed insulating resin film to the substrate.

3. The method according to claim 1 or 2, wherein the minimum melt viscosity of the insulating resin film is 3000 Pa·s or more.

4. The method according to any one of claims 1 to 3, wherein the reaction peak temperature is 160°C or less.

5. The method according to any one of claims 1 to 4, wherein the insulating resin film contains filler.

6. The method according to any one of claims 1 to 5, wherein the ratio of the height of the via hole to the maximum width of the via hole is 3.0 or more.

7. The method according to any one of claims 1 to 6, wherein the maximum width of the via hole is 5.0 μm or less.

8. The method according to any one of claims 1 to 7, wherein the difference between the molding temperature and the reaction peak temperature is 100°C or more.

9. A method for manufacturing a semiconductor package, comprising forming a rewiring layer by the method according to any one of claims 1 to 8.

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