Semiconductor device and composition for forming rear surface protective film

Abstract

The semiconductor device comprises a semiconductor substrate, a back surface protective film that protects the back surface of the semiconductor substrate, and an anti-counterfeiting layer that is provided on the back surface protective film and contains a pattern-forming substance that forms an authenticity determination pattern, and the back surface protective film contains an inorganic pigment.

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device and a composition for forming a back surface protective film. [Background technology]

[0002] In the field of semiconductor devices, the distribution of counterfeit products has become a problem. Therefore, there is a demand for technology that can determine the authenticity of semiconductor devices. To determine authenticity, it is conceivable to attach a unique pattern to the semiconductor device in advance.

[0003] In relation to the above, Patent Document 1 (JP Patent Publication No. 2007-242973) describes a semiconductor device having a structure in which a semiconductor circuit is sealed with sealing resin, the semiconductor device having a semiconductor circuit and sealing resin with a mottled pattern (authenticity determination pattern) on at least its surface that differs for each individual device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-242973 Summary of the Invention

[0005] Incidentally, some semiconductor devices are known to be mounted face-down. In such semiconductor devices, the circuit-forming surface of the semiconductor substrate (semiconductor chip) faces the mounting board. In face-down semiconductor devices, the back surface of the semiconductor substrate is exposed after mounting. Therefore, a back surface protective film is sometimes provided on the back surface of the semiconductor substrate to protect the back surface.

[0006] When an authenticity determination pattern is formed on such a back surface protective film, the authenticity determination pattern is imaged during the manufacture of the semiconductor device, and data indicating the authenticity determination pattern is stored as authentic product data. If authenticity determination becomes necessary after the semiconductor device is distributed, the authenticity determination pattern of the product to be determined is imaged. The authenticity determination pattern of the product to be determined is then compared with the pre-stored authentic product data to determine its authenticity.

[0007] However, when an image of a genuine product is taken, the image obtained may differ from that obtained when an image of a product to be judged is taken, which may result in failure to accurately judge the authenticity of the product.

[0008] Therefore, an object of the present invention is to provide a technology that can accurately determine the authenticity of products that have been distributed.

[0009] The inventors discovered that the above-mentioned problems can be solved by providing an anti-counterfeiting layer containing a pattern-forming substance that forms an authenticity determination pattern on a back surface protective film, and by using an inorganic pigment in the back surface protective film, and thus arrived at the present invention.

[0010] That is, in one aspect, the present invention relates to a semiconductor device. The semiconductor device includes a semiconductor substrate, a back surface protective film that protects the back surface of the semiconductor substrate, and a counterfeit prevention layer that is provided on the back surface protective film and contains a pattern forming material that forms an authentication pattern. The back surface protective film contains an inorganic pigment.

[0011] In another aspect, the present invention relates to a composition for forming a back surface protective film, which is used to form a back surface protective film in the above-mentioned semiconductor device.

[0012] According to the present invention, optical changes such as discoloration of the back surface protective film are unlikely to occur even after heat treatment, and as a result, a semiconductor device is provided in which, when observing the anti-counterfeit layer provided separately from the back surface protective film on the product to be inspected, an image of the authenticity determination pattern is unlikely to change from an image of the genuine product. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a semiconductor device according to an embodiment. [Figure 2] FIG. 2 is a plan view showing an example of the anti-counterfeit layer. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] (1) Semiconductor device 1 is a cross-sectional view schematically showing a semiconductor device 1 according to this embodiment. The semiconductor device 1 has a semiconductor substrate 2, a back surface protective film 3, and an anti-counterfeit layer 4. The semiconductor device 1 is mounted face-down. That is, it is mounted on a mounting board with the circuit-forming surface of the semiconductor substrate 2 facing the mounting board.

[0016] The semiconductor substrate 2 is a semiconductor chip on which an integrated circuit 7 is formed. The semiconductor substrate 2 is typically made of silicon.

[0017] The back surface protective film 3 is provided on the back surface (the surface opposite to the surface on which the integrated circuit 7 is formed) of the semiconductor substrate 2. The back surface protective film 3 contains an inorganic pigment. That is, the back surface protective film 3 is colored by the inorganic pigment.

[0018] The anti-counterfeit layer 4 is provided on the back surface protective film 3. The anti-counterfeit layer 4 is a layer used to determine the authenticity of the semiconductor device 1. The anti-counterfeit layer 4 contains a pattern-forming material 5. A pattern for determining the authenticity of the semiconductor device 1 (hereinafter, sometimes simply referred to as an authenticity pattern) is formed on the anti-counterfeit layer 4 by the pattern-forming material 5. The authenticity pattern is a pattern unique to the semiconductor device 1. The authenticity pattern is preferably a pattern that cannot be recognized by the naked eye but can be recognized using an optical microscope.

[0019] FIG. 2 is a plan view showing an example of the anti-counterfeit layer 4 and shows an authentication pattern. FIG. 2 shows an image obtained when the anti-counterfeit layer 4 is observed with an optical microscope. As shown in FIG. 2, the pattern-forming substance 5 is particulate and randomly dispersed within the anti-counterfeit layer 4. More preferably, the pattern-forming substance 5 is formed of particles that are observed as bright spots when the anti-counterfeit layer 4 is observed with an optical microscope. The pattern formed by the bright spots is used as the authentication pattern. Note that the bright spots are not necessarily limited to those that can be visually observed with an optical microscope. For example, the bright spots may be points that emit substantially no scattered light in the visible range but emit scattered light in the near-infrared range. In such cases, the bright spots can be recognized not visually but with an infrared sensor.

[0020] The above is a schematic configuration of the semiconductor device 1 according to this embodiment.

[0021] In this embodiment, the anti-counterfeit layer 4 of the genuine product is imaged in advance by an imaging device, and genuine product data is generated and saved. The genuine product data is data that indicates the pattern for determining the authenticity of the genuine product.

[0022] After the authenticity data is generated, the semiconductor device 1 is mounted on a mounting board. The semiconductor device 1 is face-down mounted, for example, by soldering. Reflow is performed during solder mounting. Reflow is performed, for example, using a reflow oven. Reflow is performed at a high temperature required for solder mounting. During reflow, the back surface protective film 3 also becomes hot. At this time, if the back surface protective film 3 is colored with, for example, a dye or organic pigment, the colorant may be altered, causing discoloration of the back surface protective film 3. In contrast, an inorganic pigment is used in this embodiment. Since inorganic pigments have higher heat resistance than dyes and organic pigments, discoloration of the back surface protective film 3 is suppressed. Furthermore, the transmittance of the back surface protective film 3 to visible light or infrared light is also less likely to change.

[0023] The mounted semiconductor device 1 is then distributed. After distribution, the authenticity of the semiconductor device 1 is determined as necessary. During authenticity determination, the anti-counterfeit layer 4 of the product to be determined is observed. The authenticity determination pattern of the product to be determined is then compared with the authentic product data to determine whether the product is authentic or not. Here, according to this embodiment, the use of inorganic pigments suppresses discoloration of the back surface protective film 3 and changes in the transmittance of visible light or infrared light, so the image of the authenticity determination pattern is less likely to change before and after a heat treatment such as reflow. Therefore, even if a heat treatment such as reflow is performed after the authentic product data is obtained, accurate authenticity determination can be performed.

[0024] The above is an outline of the semiconductor device 1 according to this embodiment. Next, the details of this embodiment will be described.

[0025] (2) Backside protection film As described above, the back surface protective film 3 is provided to protect the back surface of the semiconductor substrate 2. The back surface protective film 3 is formed from a composition for forming a back surface protective film. The composition for forming a back surface protective film is preferably a curable resin composition. For example, the back surface protective film 3 is formed by disposing the composition for forming a back surface protective film on the semiconductor substrate 2 and curing the disposed composition for forming a back surface protective film. The composition for forming a back surface protective film may be a thermosetting composition or an energy ray-curable composition. Alternatively, it may be a composition that has both thermosetting and energy ray-curing properties.

[0026] The back surface protective film-forming composition is preferably provided in the form of a film. A film-like composition for forming a back surface protective film is hereinafter referred to as a back surface protective film-forming film. The back surface protective film-forming film is provided, for example, in a form supported on a support film. By laminating the back surface protective film-forming film, the back surface protective film-forming composition is disposed on the semiconductor substrate 2. Thereafter, the back surface protective film 3 can be formed by curing the back surface protective film-forming composition on the semiconductor substrate 2.

[0027] The thickness of the back surface protection film 3 is, for example, 1 to 100 μm, and preferably 5 to 50 μm.

[0028] The substances contained in the back surface protective film 3 will be described in more detail below by explaining the composition of the back surface protective film-forming composition.

[0029] (inorganic pigments) As described above, the back surface protective film-forming composition contains an inorganic pigment. Examples of inorganic pigments include black pigments and white pigments. Examples of black pigments include carbon black, titanium black, graphite, iron black, chromium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments. Carbon black is preferred. Examples of white pigments include titanium oxide, calcium carbonate, zinc oxide, and barium sulfate. The back surface protective film-forming composition containing an inorganic pigment and coloring the back surface protective film can provide various effects, such as providing design, concealing grinding marks on the surface of the semiconductor substrate on which the back surface protective film is formed, improving the contrast of markings on the surface of the back surface protective film, and shielding electromagnetic waves such as infrared rays from the back surface protective film.

[0030] The content of the inorganic pigment is not particularly limited, and for example, the content of the inorganic pigment in the composition for forming a back surface protective film excluding the solvent (which also corresponds to the content of the inorganic pigment in the back surface protective film) is, for example, 0.01 to 1 mass %, and preferably 0.05 to 0.5 mass %.

[0031] (filler) The composition for forming the back surface protective film preferably contains a filler, which is used to adjust the physical properties of the back surface protective film 3.

[0032] Spherical fillers are preferably used as the filler. Using spherical fillers can further improve the accuracy of authenticity determination. As described above, the anti-counterfeit layer 4 is typically imaged using an optical microscope. Illumination light is then applied. If the underlying back surface protection film 3 contains amorphous fillers, the illumination light incident on the back surface protection film 3 through the anti-counterfeit layer 4 is reflected according to the angle of the filler surface. Therefore, the intensity and color of the reflected light may change depending on the incident direction of the illumination light. Therefore, differences in the illumination environment may result in differences in the authenticity determination pattern. Because the illumination environment may differ between the time of acquiring authentic product data and the time of authenticity determination, differences in the illumination environment may prevent accurate authentication determination. In contrast, if the filler is spherical, the intensity and direction of the reflected light from the filler are less dependent on the incident direction of the illumination light. Therefore, the same authentication determination pattern is likely to be obtained even under different lighting conditions. This allows for more accurate authentication determination.

[0033] The shape of the filler in the back surface protective film-forming composition or back surface protective film can be confirmed, for example, by dissolving components (such as resin) other than the filler contained in the back surface protective film-forming composition or back surface protective film, extracting only the filler, and observing the extracted filler under a microscope, etc. Alternatively, the back surface protective film-forming composition or back surface protective film may be baked to remove components other than the filler that function as a binder, thereby extracting only the filler.

[0034] The content of the spherical filler in the composition for forming a back surface protective film (i.e., the content of the spherical filler in the back surface protective film) is preferably 30 to 70 mass % relative to the total mass of the composition for forming a back surface protective film (calculated as active ingredients excluding the solvent). When the content of the spherical filler is 30 mass % or more, the physical properties of the back surface protective film can be made sufficiently close to those of the semiconductor substrate. When the content is 70 mass % or less, the toughness of the back surface protective film can be increased, making it easier to obtain a better image when imaging the anti-counterfeit layer. More preferably, the content of the spherical filler is 35 to 65 mass % relative to the total mass of the back surface protective film.

[0035] The composition for forming a back surface protective film may contain fillers other than spherical fillers. However, preferably, 80% by mass or more of the total fillers are spherical fillers. More preferably, 90% by mass or more of the total fillers are spherical fillers, and even more preferably, 95% by mass or more of the total fillers are spherical fillers. Most preferably, substantially all of the fillers are spherical fillers.

[0036] The spherical filler may be either an oblate spheroid or a perfect sphere, and preferably is a perfect sphere.

[0037] The material of the filler is not particularly limited. The filler may be an inorganic filler or an organic filler. Preferably, it is an inorganic filler. Examples of inorganic fillers include at least one selected from the group consisting of silica, alumina, aluminum compounds such as aluminum nitride, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, and boron nitride. From the viewpoint of easily obtaining spherical fillers, the filler is preferably at least one selected from silica, aluminum compounds, and boron nitride. From the viewpoint of obtaining fillers that are close to perfect spheres, the filler is more preferably at least one selected from silica and aluminum compounds, and even more preferably silica.

[0038] The size of the filler is not particularly limited. The average particle size of the filler is, for example, 0.05 to 5 μm, preferably 0.1 to 3.0 μm, and more preferably 0.1 to 1.0 μm. The average particle size here refers to the median diameter D50 in the particle size distribution measured using a laser diffraction particle size distribution analyzer.

[0039] (Thermosetting composition for forming a back surface protective film) As described above, the composition for forming a back surface protective film may be a thermosetting composition or an energy ray-curable composition. The composition of the thermosetting composition will be described below.

[0040] When the composition for forming a back surface protective film is a thermosetting composition, it can contain, in addition to the inorganic pigment and filler described above, a polymer component (A), a thermosetting component (B), a curing accelerator (C), a coupling agent (D), and the like.

[0041] (A) Polymer component Examples of the polymer component (A) include acrylic resins (e.g., resins obtained by addition polymerization of monomers containing at least an acrylic acid ester monomer), polyesters, urethane resins (e.g., resins having a urethane bond), acrylic urethane resins, silicone resins (e.g., resins having a siloxane bond), rubber resins (e.g., resins having a rubber structure), and phenoxy resins, with acrylic resins being preferred.

[0042] The content of polymer component (A) is, for example, 5 to 50 mass %, preferably 10 to 40 mass %, and more preferably 15 to 35 mass %, based on the total mass of the composition for forming a back surface protective film excluding the solvent.

[0043] (B) Thermosetting component The thermosetting component (B) is a component that is cured by heat. Examples of the thermosetting component include epoxy-based thermosetting resins, thermosetting polyurethanes, unsaturated polyesters, and silicone rubbers. Epoxy-based thermosetting resins are preferred.

[0044] The epoxy thermosetting resin may contain, for example, an epoxy resin (B1) and a thermosetting agent (B2).

[0045] Examples of the epoxy resin (B1) include bifunctional or higher functional epoxy compounds such as polyfunctional epoxy resins, biphenyl compounds, bisphenol A diglycidyl ether and its hydrogenated products, orthocresol novolac epoxy resins, dicyclopentadiene epoxy resins, biphenyl epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, and phenylene skeleton epoxy resins. Among these, bisphenol A epoxy resins and dicyclopentadiene epoxy resins are preferred.

[0046] The thermosetting agent (B2) is a substance that functions as a curing agent for epoxy resins. Examples of thermosetting agents include compounds having at least two functional groups per molecule that can react with epoxy groups. Examples of such functional groups include phenolic hydroxyl groups, alcoholic hydroxyl groups, amino groups, carboxy groups, and groups resulting from anhydride conversion of acid groups. Preferably, the thermosetting agent includes an amino-based curing agent having an amino group. Examples of amino-based curing agents include dicyandiamide.

[0047] The content of the thermosetting component (B) (e.g., the total content of the epoxy resin (B1) and the thermosetting agent (B2)) is, for example, 5 to 30 mass %, preferably 15 to 20 mass %, relative to the total mass of the composition for forming a back surface protection film excluding the solvent.

[0048] (C) Curing accelerator Examples of the curing accelerator (C) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles (imidazoles in which at least one hydrogen atom is substituted with a group other than a hydrogen atom) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organic phosphines (phosphines in which at least one hydrogen atom is substituted with an organic group) such as tributylphosphine, diphenylphosphine, and triphenylphosphine; and tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. Preferably, the curing accelerator (C) includes 2-phenyl-4,5-dihydroxymethylimidazole.

[0049] The content of the curing accelerator (C) is, for example, 0.1 to 1 mass % relative to the total mass of the composition for forming a back surface protective film excluding the solvent.

[0050] (D) Coupling Agent As the coupling agent (D), for example, a silane coupling agent is used. Examples of the silane coupling agent include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxymethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethylamino) ... Examples of suitable silanes include bis(3-triethoxysilylpropyl)tetrasulfane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazole silane.

[0051] The content of the silane coupling agent (D) is, for example, 0.1 to 1 mass % relative to the total mass of the composition for forming a back surface protective film excluding the solvent.

[0052] (Energy ray-curable composition for forming a back surface protective film) As described above, the composition for forming a back surface protective film may be an energy-curable composition. In this case, the composition for forming a back surface protective film is not particularly limited. For example, an energy-ray-curable composition for forming a back surface protective film can be obtained by including an energy-ray-curable compound and a photopolymerization initiator, which will be described later with respect to the "anti-counterfeit layer."

[0053] (3) Anti-counterfeiting layer Next, the anti-counterfeit layer will be described. As described above, the anti-counterfeit layer contains a pattern forming material. The pattern forming material forms an authenticity pattern on the anti-counterfeit layer.

[0054] The thickness of the anti-counterfeit layer 4 is, for example, 0.1 to 20 μm, preferably 0.2 to 10 μm, and more preferably 0.5 to 5 μm.

[0055] The anti-counterfeit layer 4 is formed from a composition for an anti-counterfeit layer. The composition for an anti-counterfeit layer may be provided in the form of a film, or, for example, in a liquid form containing a solvent, or in the form of a solventless liquid curable composition obtained by blending and fluidizing a low-molecular-weight polymerizable monomer. The composition for an anti-counterfeit layer is preferably a resin composition. That is, the anti-counterfeit layer 4 is a cured product of the resin composition, and the pattern-forming material is dispersed in the resin. The anti-counterfeit layer 4 can be formed by supplying a curable composition for an anti-counterfeit layer onto the back surface protective film 3 and curing it.

[0056] The composition of the anti-counterfeit layer composition will be explained below, and the structure of the anti-counterfeit layer will be explained.

[0057] (Pattern-forming materials) As described above, the composition for the anti-counterfeit layer contains a pattern-forming material. As described above, the pattern-forming material is preferably particulate. Specifically, it is preferably a particulate material that generates bright spots when observed using an optical microscope. If such particulate pattern-forming material is randomly dispersed, the bright spots derived from each particle can be used as a pattern for determining authenticity. Since it is only necessary to randomly disperse each particle, a pattern for determining authenticity can be easily formed.

[0058] Preferably, the pattern forming material contains a plurality of particles that emit different colors. This configuration allows for the formation of more complex patterns. The more complex the patterns formed, the greater the amount of information available for authenticity determination, making it possible to perform authenticity determination with greater accuracy.

[0059] Preferably, the pattern forming material contains a plurality of particles having different shapes, which allows for the formation of more complex patterns.

[0060] Specific examples of pattern-forming materials include pearl pigments and effect pigments. Examples of pearl pigments include pigments in which a substrate, such as a mica frame, is coated with a metal oxide (such as titanium oxide or iron oxide). Examples of effect pigments include pigments in which a substrate, such as synthetic alumina flakes, synthetic silica flakes, borosilicate glass flakes, titanium oxide coatings, and synthetic mica flakes, is coated with a metal oxide (such as titanium oxide or iron oxide). Alternatively, a common silica filler can be used as the pattern-forming material.

[0061] The average particle size of the pattern forming material is, for example, 0.05 to 5.0 μm, and preferably 0.1 to 1.0 μm. The average particle size here refers to the median diameter D50 in the particle size distribution measured using a laser diffraction particle size distribution analyzer.

[0062] The content of the pattern forming substance is, for example, 0.01 to 5 mass %, and preferably 0.05 to 1 mass %, based on the total mass of the composition for the anti-counterfeit layer excluding the solvent.

[0063] (Other components in the anti-counterfeit layer) As described above, the composition for the anti-counterfeit layer is preferably a curable resin composition. That is, the pattern-forming substance described above is preferably dispersed in a resin. The composition for the anti-counterfeit layer may be a thermosetting composition or an energy ray-curable composition. It may also be a composition that has both thermosetting and energy ray-curing properties. Note that, if the curing type of the composition for the anti-counterfeit layer is the same as that of the composition for forming a back surface protective film, the composition for forming a back surface protective film and the composition for the anti-counterfeit layer can be cured together.

[0064] For example, in the case of an energy ray-curable composition, the composition for the anti-counterfeit layer contains an energy ray-curable compound (for example, a monomer or oligomer) and a photopolymerization initiator.

[0065] Examples of the energy ray-curable compound include polyvalent (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate, and oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate. Preferably, polyester (meth)acrylate is used.

[0066] As the energy ray-curable compound, a polymer having a photopolymerizable functional group such as a (meth)acryloyl group or a vinyl group in a side chain may be used. For example, an acrylic polymer can be used as such a polymer, and a method is known in which an acrylic polymer having a reactive functional group such as a hydroxyl group in a side chain is reacted with a compound having a photopolymerizable functional group and capable of reacting with the reactive functional group, such as methacryloyloxyisocyanate, to add the photopolymerizable functional group to the side chain.

[0067] When these energy ray-curable compounds are used, the photopolymerization initiator is preferably a photoradical polymerization initiator.

[0068] The content of the energy ray-curable compound is, for example, 70 to 99 mass %, and preferably 80 to 95 mass %, based on the total mass of the composition for the anti-counterfeit layer excluding the solvent.

[0069] The photopolymerization initiator is not particularly limited, and the content of the photopolymerization initiator is, for example, 0.5 to 15% by mass, and preferably 1 to 10% by mass, based on the total mass of the composition for the anti-counterfeit layer excluding the solvent.

[0070] The composition for the anti-counterfeit layer may also contain a silane coupling agent. When the filler contained in the back surface protective film is an inorganic filler, the inclusion of a silane coupling agent in the anti-counterfeit layer can improve adhesion between the anti-counterfeit layer and the back surface protective film, thereby preventing peeling or falling off of the anti-counterfeit layer. The amount of the silane coupling agent is, for example, 0.5 to 15 mass %, preferably 1 to 10 mass %, based on the total mass of the composition for the anti-counterfeit layer excluding the solvent.

[0071] As described above, the composition for the anti-counterfeit layer may be a thermosetting composition. The thermosetting composition for the anti-counterfeit layer can be realized, for example, by a composition containing the polymer component (A) and the thermosetting component (B) described in the "Composition for forming a back surface protective film" section.

[0072] (4) Manufacturing method and authenticity determination method Next, an example of a method for manufacturing the semiconductor device 1 and a method for determining authenticity will be described.

[0073] First, a semiconductor substrate 2 is prepared, and a back surface protective film 3 is formed on the back surface of the semiconductor substrate 2. Specifically, a composition for forming a back surface protective film is supplied onto the back surface of the semiconductor substrate 2. The composition for forming a back surface protective film is then cured. This forms the back surface protective film 3. Subsequently, a composition for forming an anti-counterfeit layer is supplied onto the back surface protective film 3. The supplied composition for forming an anti-counterfeit layer is then cured. This forms the anti-counterfeit layer 4. This results in a semiconductor device 1.

[0074] Next, the anti-counterfeit layer 4 is imaged with an optical microscope, and authentic product data indicating the pattern for determining authenticity is generated. The authentic product data is stored in a server or the like.

[0075] Thereafter, the semiconductor device 1 is mounted face-down on a mounting board by reflow soldering. The reflow treatment conditions are preferably, for example, a maximum heating temperature of 180 to 380°C and a reflow time of 2 to 10 minutes. After mounting, the semiconductor device 1 is distributed.

[0076] After distribution, the authenticity of the semiconductor device 1 is determined as necessary. When determining authenticity, the anti-counterfeit layer of the product to be determined is observed using an optical microscope. Then, the authenticity determination pattern of the product to be determined is compared with the genuine product data to determine whether the product to be determined is genuine. The comparison process may be performed by visually inspecting the image data, or by comparing data extracted by image analysis using a computer or the like with the data extracted from the above-mentioned genuine product. In this case, according to this embodiment, since discoloration of the back surface protection film 3 is unlikely to occur during reflow, authenticity can be determined with high accuracy.

[0077] The curing of the back surface protective film-forming composition and the curing of the anti-counterfeit layer composition may be performed simultaneously. That is, the back surface protective film-forming composition is supplied onto the semiconductor substrate 2. Next, before the curing of the back surface protective film-forming composition, the anti-counterfeit layer composition is supplied onto the back surface protective film-forming composition. The back surface protective film-forming composition and the anti-counterfeit layer composition are then cured simultaneously. For example, if the back surface protective film-forming composition and the anti-counterfeit layer composition are both heat-curable, the back surface protective film-forming composition and the anti-counterfeit layer composition can be cured simultaneously by heating. Alternatively, if the back surface protective film-forming composition and the anti-counterfeit layer composition are both energy ray-curable, the two can be cured simultaneously by irradiating them with energy rays. This shortens the manufacturing process. Furthermore, the anti-counterfeit layer composition may be cured before the back surface protective film-forming composition is cured. However, in this case, if the curing types of the composition for forming the back surface protective film and the composition for forming the anti-counterfeit layer are the same, there is a high possibility that the composition for forming the back surface protective film will be at least partially cured at the same time as the composition for forming the anti-counterfeit layer is cured.

[0078] The semiconductor device 1 may be fabricated by a so-called wafer-level packaging process or a panel-level packaging process. Examples of wafer-level packaging processes include wafer-level chip-size packaging (WLCSP) and fan-out wafer-level packaging. Examples of panel-level packaging processes include fan-out panel-level packaging. In these packaging processes, a rear surface protective film 3 is formed simultaneously on multiple semiconductor devices 1 at the wafer level. The multiple semiconductor devices 1 are then singulated. The anti-counterfeit layer 4 can be formed simultaneously after the formation of the rear surface protective film 3 and before singulation. This is efficient because the anti-counterfeit layer 4 can be formed simultaneously on multiple semiconductor devices 1.

[0079] In the above example, the case where the authentic product is imaged after the anti-counterfeit layer composition has cured has been described. However, the timing of imaging the authentic product may be any timing after the anti-counterfeit layer composition has been supplied. That is, the authenticity determination pattern may be imaged after the anti-counterfeit layer composition has been supplied onto the back surface protective film 3 and before the anti-counterfeit layer composition has cured. That is, the authentic semiconductor device may be a semi-finished product.

[0080] The comparison of the authenticity determination pattern of the product to be determined with the genuine product data may be performed visually or by image analysis using a computer or the like.

[0081] The lighting environment when capturing images of the authentic product and the product to be judged is not particularly limited. For example, it may be side lighting, direct lighting, a combination of both, or other lighting.

[0082] The size of the image used to compare the genuine product and the product to be judged is not particularly limited. For example, authenticity can be judged using an image of an area in the anti-counterfeit layer with one side measuring 10 to 1000 μm.

[0083] The magnification of the optical microscope used to capture an image of the authentic product and observe the product to be judged is not particularly limited. For example, an optical microscope with a magnification of 300 to 3000 times can be used. [Example]

[0084] Next, in order to explain the present invention in more detail, examples carried out by the present inventors will be described, but the present invention should not be construed as being limited to the following examples.

[0085] (1) Preparation of a composition for forming a back surface protective film The components were mixed according to the formulation shown in Table 1 and diluted with methyl ethyl ketone to a solids concentration of 61 mass % to prepare a composition for forming a back surface protective film according to Example 1. Compositions for forming a back surface protective film according to Comparative Example 1 and Comparative Example 2 were also prepared by the same method.

[0086] [Table 1]

[0087] The blending amounts in Table 1 are in parts by mass. Specifically, the following components were used.

[0088] [Polymer component] A (meth)acrylic acid ester copolymer (weight average molecular weight: 800,000) obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 70 parts by mass of methyl acrylate, 5 parts by mass of glycidyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate.

[0089] [Liquid Bis-A type epoxy resin] Bisphenol A epoxy resin (Mitsubishi Chemical Corporation, jER828)

[0090] [Solid Bis-A type epoxy resin] Bisphenol A epoxy resin (Mitsubishi Chemical Corporation, jER1055)

[0091] [DCPD type epoxy resin] Dicyclopentadiene epoxy resin (Dainippon Ink and Chemicals, Epicron HP-7200HH)

[0092] [Thermal hardener] Heat-activated latent epoxy resin hardener: dicyandiamide (ADEKA Corporation, ADEKA Hardener EH-3636AS)

[0093] [Curing accelerator] 2-Phenyl-4,5-dihydroxymethylimidazole (Curezol 2PHZ, manufactured by Shikoku Chemicals Corporation)

[0094] [Filler] Silica filler (Admatechs, SC2050MA, average particle size 0.5 μm)

[0095] [Carbon black] Carbon black (Mitsubishi Chemical, #MA650, average particle size 28 nm)

[0096] [dye] Dye (Orient Chemical Industry Co., Ltd., OIL BLACK 860)

[0097] [Organic pigments] Organic pigment (Sanyo Pigment Co., Ltd., D1201M)

[0098] [Coupling agent] Silane coupling agent (Nippon Unicar Co., Ltd., A-1110), oligomer type

[0099] (2) Preparation of backside protective film A first release sheet (manufactured by Lintec Corporation: SP-PET3811, thickness 38 μm) consisting of a polyethylene terephthalate (PET) film with a silicone-based release agent layer formed on one side, and a second release sheet (manufactured by Lintec Corporation: SP-PET381031, thickness 38 μm) consisting of a PET film with a silicone-based release agent layer formed on one side were prepared. The above-mentioned back surface protective film-forming composition was applied to the release surface of the first release sheet using a knife coater and then dried in an oven at 120°C for 2 minutes. Next, the release surface of the second release sheet was laminated onto the back surface protective film-forming composition. This resulted in a back surface protective film-forming film (thickness 25 μm) sandwiched between the first and second release sheets.

[0100] (3) Measurement of light transmittance The second release sheet was peeled off from the film for forming a back surface protection film obtained in Examples and Comparative Examples, and the film for forming a back surface protection film was heated in an oven under atmospheric conditions at 130°C for 2 hours to thermally cure the film for forming a back surface protection film into a protective film. Then, the first release sheet was peeled off.

[0101] The transmittance of the resulting protective film was measured using a spectrophotometer (Shimadzu UV-Vis-NIR Spectrophotometer UV-3600) to extract the light transmittance (%) at wavelengths of 550 nm (visible light) and 1600 nm (infrared light). The measurements were performed using the attached large sample chamber MPC-3100 without using the built-in integrating sphere.

[0102] Furthermore, using an IR reflow device (STR-2010M, manufactured by Senju Metal Industry Co., Ltd.), the protective film was subjected to a reflow process under the conditions listed in Table 2, after which the light transmittance was measured again. Cases where the difference in light transmittance at each of the above wavelengths before and after the reflow process was less than 2% were evaluated as A, and cases where the difference in light transmittance was 2% or more were evaluated as B. The change in appearance before and after reflow was also observed. The results are shown in Table 3.

[0103] [Table 2] [Table 3]

[0104] (Discussion of results) In Comparative Examples 1 and 2, which used colorants other than inorganic pigments, the light transmittance changed significantly in either visible light or infrared light, and the appearance also changed. In contrast, in Example 1, which used an inorganic pigment, the light transmittance changed only slightly in either visible light or infrared light, and there was no change in appearance. In other words, it was confirmed that the use of an inorganic pigment as a colorant suppresses discoloration due to reflow, and is suitable as a base layer for an anti-counterfeit layer.

[0105] [Note] The configuration included in this embodiment will be summarized below as an appendix.

[0106] (Appendix 1) 1. A semiconductor device comprising: a semiconductor substrate; a back surface protective film that protects the back surface of the semiconductor substrate; and an anti-counterfeit layer that is provided on the back surface protective film and contains a pattern forming substance that forms an authenticity determination pattern, wherein the back surface protective film contains an inorganic pigment.

[0107] (Appendix 2) 2. The semiconductor device of claim 1, wherein the pattern formation material is in particulate form.

[0108] (Appendix 3) 3. The semiconductor device of claim 2, wherein the pattern forming material includes a plurality of particles that emit different colors.

[0109] (Appendix 4) 4. The semiconductor device of claim 2, wherein the patterning material includes a plurality of particles having different shapes.

[0110] (Appendix 5) A composition for forming a back surface protective film, used to form the back surface protective film in the semiconductor device according to any one of Appendices 1 to 4.

[0111] (Incorporated by reference) This application claims the benefit of priority based on Japanese patent applications (application number 2024-037352 and application number 2024-042809), which are incorporated herein by reference. [Explanation of symbols]

[0112] 1. Semiconductor device, 2. Semiconductor substrate, 3. Backside protective film, 4. Anti-counterfeit layer, 5. Patterning material, 7. Integrated circuit

Claims

1. a semiconductor substrate; a back surface protective film for protecting the back surface of the semiconductor substrate; a counterfeit prevention layer provided on the rear surface protective film and containing a pattern forming material for forming an authenticity determination pattern; Equipped with The back surface protective film contains an inorganic pigment. Semiconductor device.

2. the pattern forming material is in particulate form; The semiconductor device according to claim 1 .

3. The patterning material includes a plurality of particles that emit different colors. The semiconductor device according to claim 2 .

4. the patterning material includes a plurality of particles having different shapes; The semiconductor device according to claim 2 .

5. A method for forming the rear surface protective film in the semiconductor device according to claim 1 or 2, Composition for forming a backside protective film.