Semiconductor equipment

Abstract

To provide a semiconductor device with high reliability because the encapsulant material does not easily deteriorate even when the SiC semiconductor elements are energized.SOLUTION: A power semiconductor module has a laminated structure in which SiC semiconductor elements 11 and laminated substrates 12 are bonded on a heat sink 13 with a bonding layer 17. A thermosetting resin sealing layer 20 is filled in contact over the SiC semiconductor elements, laminated substrates, lead frames 18, aluminum wires 14 as conductive connection members, and other sealed members. In other words, the encapsulant material consists substantially of a thermosetting resin sealing layer, and the thermosetting resin sealing layer 20 functions as a UV absorbing layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a semiconductor device. In particular, even when a SiC semiconductor element is used, the present invention relates to a highly reliable semiconductor device in which deterioration of the resin for sealing the SiC semiconductor element hardly occurs.

Background Art

[0002] Power semiconductor modules are widely applied in fields where efficient power conversion is required. For example, the application areas are expanding in the power electronics fields such as industrial equipment, electric vehicles, and home appliances. These power semiconductor modules incorporate switching elements and diodes, and Si (silicon) semiconductor elements or SiC (silicon carbide) semiconductor elements are used for the elements.

[0003] Among them, since the breakdown electric field strength of the SiC semiconductor element is about 10 times higher than that of the Si semiconductor element, a high-voltage power device of 600 V to several thousand V can be fabricated with a high impurity concentration and a thin film thickness drift layer as compared with the Si semiconductor element. Therefore, the SiC semiconductor element is being put into practical use as a high-voltage device with a very low on-resistance per unit area.

[0004] Conventionally, as a sealing material for semiconductor elements, resins containing various functional materials are known, and resins containing ultraviolet absorbers are known for the purpose of sealing optical semiconductor elements (see, for example, Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0005] [[ID=JO]]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a voltage is applied to a SiC semiconductor device during operation, it emits ultraviolet (UV) light with a wavelength of about 360 nm to about 400 nm, having a main wavelength (peak wavelength) of 393 nm corresponding to the bandgap of SiC. It has become clear that this UV may deteriorate the encapsulating resin of the SiC semiconductor device. Specifically, deterioration of the encapsulating resin includes generation of cracks in the resin around the chip, etc., which reduces reliability such as power cycling.

Means for Solving the Problems

[0007] As a result of intensive studies, the inventors of the present invention have conceived that in a power semiconductor module using a SiC semiconductor device, by disposing an ultraviolet absorber in the encapsulant in a predetermined manner, it is possible to prevent deterioration of the encapsulating resin and prevent a decrease in reliability, and thus have completed the present invention.

[0008] That is, according to one embodiment, the present invention relates to a semiconductor device, which is a semiconductor device obtained by encapsulating a SiC semiconductor device mounted on a laminated substrate and a conductive connection member with an encapsulant containing an ultraviolet absorber.

[0009] In the semiconductor device, it is preferable that the encapsulant includes a thermosetting resin encapsulation layer, and the thermosetting resin encapsulation layer includes a thermosetting resin main agent, a curing agent, an inorganic filler, and an ultraviolet absorber.

[0010] In the semiconductor device, in a certain embodiment, it is preferable that the thermosetting resin encapsulation layer is composed of a layer containing a thermosetting resin main agent, a curing agent, an inorganic filler, and an ultraviolet absorber.

[0011] In one embodiment of the semiconductor device, the thermosetting resin encapsulation layer preferably includes a first encapsulation layer that covers the periphery of a SiC semiconductor element and a second encapsulation layer that covers the first encapsulation layer, wherein the first encapsulation layer preferably includes a thermosetting resin main component, a curing agent, an inorganic filler, and an ultraviolet absorber.

[0012] In one embodiment of the semiconductor device, the encapsulating material preferably includes a primer layer that covers the SiC semiconductor element and the conductive connecting member, and a thermosetting resin encapsulating layer that covers the primer layer, wherein the primer layer preferably contains an ultraviolet absorber.

[0013] In the semiconductor device described above, it is preferable that the ultraviolet absorber is one or more selected from benzotriazole derivatives, benzophenone derivatives, or triazine derivatives.

[0014] In the semiconductor device comprising the thermosetting resin, it is preferable that the thermosetting resin main component includes an epoxy resin main component.

[0015] In a semiconductor device comprising the primer layer, it is preferable that the primer layer contains one or more resins selected from polyamide resins, polyimide resins, and polyamide-imide resins. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a highly reliable semiconductor device that can absorb ultraviolet light generated by a SiC semiconductor element and suppress the degradation of the resin constituting the encapsulating material. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a conceptual cross-sectional view showing the cross-sectional structure of a semiconductor device according to the first embodiment of the present invention. [Figure 2] Figure 2 is a conceptual cross-sectional view showing the cross-sectional structure of a semiconductor device according to a second embodiment of the present invention. [Figure 3]Figure 3 is a conceptual cross-sectional view showing a partial cross-sectional structure of a semiconductor device according to the third embodiment of the present invention. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[0019] According to one embodiment, the present invention relates to a semiconductor device. The semiconductor device according to this embodiment is a semiconductor device in which a SiC semiconductor element mounted on a multilayer substrate and an output terminal are connected by a conductive connecting member and sealed with a sealing material, wherein the sealing material comprises an ultraviolet absorber.

[0020] In the present invention, the term "encapsulating material" refers to an insulating resin material that is in contact with at least a SiC semiconductor element, and typically in contact with the SiC semiconductor element, output terminals, conductive connecting members, and laminated substrate, thereby insulating and encapsulating them. Therefore, in the present invention, the term "encapsulating material" encompasses both a primer layer mainly containing a thermoplastic resin and an insulating thermosetting resin layer mainly containing a thermosetting resin. The present invention also includes semiconductor devices that do not have a primer layer and are equipped with an encapsulating material mainly containing a thermosetting resin layer.

[0021] The semiconductor device according to the present invention comprises a encapsulating material containing one or more different resin layers, at least one of which is an ultraviolet absorption layer containing an ultraviolet absorber that absorbs ultraviolet light emitted by a SiC semiconductor element. In particular, the ultraviolet absorber can be an organic material that absorbs ultraviolet light at 390 nm, and it is especially preferable that the material absorbs 30% or more of the ultraviolet light at a wavelength of 370 nm emitted by the SiC semiconductor element. The ultraviolet absorption rate (%) of a specific material can be measured using an ultraviolet-visible spectrophotometer. Specifically, a predetermined amount of ultraviolet absorber can be dispersed in toluene, and the transmittance can be measured while the material is still in liquid form using a cell with a width (transmitted length) of 1 cm. At this time, the ultraviolet absorption rate (%) can be evaluated from the transmittance at 370 nm by changing the measurement wavelength in the range of 290 to 410 nm.

[0022] Specific compounds that absorb more than 30% of 370nm ultraviolet light include benzotriazole derivatives without phenyl substituents, benzotriazole derivatives represented by formula (1) below, benzophenone derivatives represented by formula (2) below, and triazine derivatives represented by formula (3) below.

[0023] Benzotriazole derivatives without phenyl substituents may be derivatives in which the hydrogen at position 1 or 3 of benzotriazole is substituted with an OH group, and the hydrogen at position 5 or 6 is substituted with a fluoromethyl group. A trifluoromethyl group is preferred as the fluoromethyl group.

[0024] The benzotriazole derivative represented by formula (1) is a derivative in which a phenyl group is bonded to the N atom at the 2 position of the triazole ring, and further comprises substituents R1 to R5 on the phenyl group and substituents R6 and R7 on the triazole ring. [ka] In formula (1), R1 and R5 are independently either H or OH. R2 and R4 are independently H, OH, a linear or branched saturated or unsaturated monovalent hydrocarbon group having 1 to 6 carbon atoms, or a linear or branched saturated or unsaturated monovalent hydrocarbon group having 1 to 6 carbon atoms in which one hydrogen atom is substituted with a phenyl group. R3 is H, OH, or a linear or branched saturated alkoxy group having 1 to 10 carbon atoms. R6 and R7 are independently either H or Cl. One or more of the H atoms constituting these substituents R1 to R7 may be substituted with Cl.

[0025] In formula (1) above, if either R1 or R5 is an OH group, it is preferable that the other is not an OH group.

[0026] If R2 and / or R4 are monovalent hydrocarbon groups, the monovalent hydrocarbon groups may be methyl, ethyl, propyl, n-butyl, or ter-butyl, with the bulkier ter-butyl group being preferred. It is even more preferable that both R2 and R4 are ter-butyl. If R2 and / or R4 are linear or branched saturated or unsaturated monovalent hydrocarbon groups having 1 to 6 carbon atoms, with one hydrogen atom substituted with a phenyl group, it is preferable that one H is substituted with a phenyl group, forming a propyl group.

[0027] If R3 is an alkoxy group, it is preferable that the alkoxy group be an octoxy group.

[0028] Specific benzotriazole derivatives include, but are not limited to, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chloro-2H-benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, 1-hydroxy-6-(trifluoromethyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole.

[0029] The benzophenone derivative is a derivative represented by the following formula (2).

Chemical formula

[0030] In the above formula (1), R 11 or R15 One substituent selected from, or R 16 Or R 17 It is preferable that one or both of the substituents selected from are OH. However, R 11 and R 15 Both are not OH at the same time, but R 16 and R 17 It is preferable that neither of them is simultaneously an OH group.

[0031] R 13 Or R 14 Preferably, one of the groups is an alkyl group or an alkoxy group, and the other is H or OH. The alkyl group is preferably a methyl group. The alkoxy group is preferably a methoxy group or an allyloxy group.

[0032] Specific examples of benzophenone derivatives include, but are not limited to, 2-hydroxy-4-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone, 4-(allyloxy)benzophenone, and 2,2'-dihydroxy-4-methoxybenzophenone.

[0033] The triazine derivative represented by formula (3) is a derivative in which a substituted or unsubstituted phenyl group is bonded to each of the three carbon atoms that make up 1,3,5-triazine. [ka] In formula (3), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 Each of these is independently selected from H, OH, a linear or branched alkoxy group having 1 to 8 carbon atoms, or a linear or branched alkyl group having 1 to 3 carbon atoms. However, R 21 From R 29One or more of these substituents are selected from OH, a linear or branched alkoxy group having 1 to 8 carbon atoms, or a linear or branched alkyl group having 1 to 3 carbon atoms. One or more of the hydrogen atoms constituting these substituents may be substituted with chlorine.

[0034] R 23 Or R 22 One substituent selected from R 24 Or R 26 One substituent selected from R 27 Or R 29 Preferably, at least one of the substituents selected from is OH, and all two or three of these substituents may be OH. However, R 23 and R 22 Both are not OH at the same time, but R 24 and R 26 Both are not OH at the same time, but R 27 and R 29 It is preferable that neither of them is simultaneously an OH group.

[0035] Furthermore, R 21 , R 25 , R 28 It is preferable that at least one of them is a linear or branched alkyl group having 1 to 3 carbon atoms. In this case, the alkyl group is particularly preferably a methyl group. Furthermore, R 21 , R 25 , R 28 Preferably, at least one of them is an alkoxy group, and more preferably, two of them are alkoxy groups, R 21 , R 25 , R 28 It is preferable that all of them are alkoxy groups. It is even more preferable that the alkoxy groups are butoxy groups or octyloxy groups. 21 , R 25 , R 28 One or two of the groups may be alkyl groups, and the rest may be alkoxy groups.

[0036] Specific examples of triazine derivatives include, but are not limited to, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris(2,4-dihydroxyphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-n-octyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine, and 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-bis-butoxyphenyl)-1,3,5-triazine.

[0037] The derivatives of benzotriazole, benzophenone, and triazine mentioned above have highly hydrophobic alkyl or phenyl groups, and therefore exhibit high dispersibility in the matrix resin (thermosetting resin or thermoplastic resin) of the UV-absorbing layer. After curing, these UV absorbers often do not react well with matrix resins such as epoxy resins, phenolic resins, or maleimide resins, and even if melted, they usually remain separate from the matrix resin and exist as particulate matter. Furthermore, derivatives with alkoxy groups are highly reactive and readily bond with inorganic materials such as inorganic fillers that may be present in the UV-absorbing layer, and with materials such as Cu that may come into contact with the UV-absorbing layer.

[0038] UV absorbers can be dispersed in powder form within the matrix resin (thermosetting resin or thermoplastic resin) of the UV-absorbing layer. From the viewpoint of dispersibility, the average particle size of the UV absorber can be 10 nm to 5000 nm, and preferably 50 nm to 500 nm. In particular, the average particle size of UV absorbers consisting of benzotriazole derivatives can be 10 nm to 1000 nm, and preferably 50 nm to 200 nm. Furthermore, benzotriazole derivatives and triazine derivatives, in particular, do not form covalent bonds with the matrix resin and have high melting points, so even if melted, they remain in particulate form after curing. Therefore, by using this range, which has a smaller particle size than the inorganic fillers detailed below, dispersibility can be improved.

[0039] In the present invention, there are multiple possible arrangements of the ultraviolet sealing layer in the sealing material. The present invention will be described in detail below with respect to the first, second, and third embodiments, which differ in the arrangement of the ultraviolet sealing layer.

[0040] [First Embodiment] The semiconductor device according to the first embodiment includes a thermosetting resin encapsulation layer as the encapsulation material, and the thermosetting resin encapsulation layer consists of a layer comprising a thermosetting resin main component, a curing agent, an inorganic filler, and an ultraviolet absorber.

[0041] Figure 1 shows a conceptual cross-sectional view of a power semiconductor module, which is an example of a semiconductor device according to the first embodiment of the present invention. The illustrated power semiconductor module has a laminated structure in which a SiC semiconductor element 11 and a laminated substrate 12 are bonded to a heat sink 13 with a bonding layer 17. A case 16 containing external terminals 15 is bonded to the heat sink 13. The electrodes of the SiC semiconductor element 11 and the laminated substrate 12 are connected by a lead frame 18, which is a conductive connecting member, and the SiC semiconductor element 11 and the external terminals 15 are connected by an aluminum wire 14. A thermosetting resin encapsulation layer 20 is filled in contact with the encapsulated members, such as the SiC semiconductor element 11, the laminated substrate 12, the lead frame 18, and the aluminum wire 14, which is a conductive connecting member. That is, the encapsulating material is substantially composed of a thermosetting resin encapsulation layer 20, and the thermosetting resin encapsulation layer 20 functions as an ultraviolet absorption layer.

[0042] The SiC semiconductor element 11 is a power chip such as an IGBT (Insulated Gate Bipolar Transistor) or a diode chip. As the semiconductor element, a combination of Si devices, GaN devices, diamond devices, ZnO devices, and other wide-bandgap semiconductor devices may be used. For example, a hybrid module using Si-IGBT and SiC-SBD can be used. The number of SiC semiconductor elements 11 mounted may be one or multiple.

[0043] The laminated substrate 12 can be composed of an insulating substrate 122, a first conductive plate 121 with a predetermined shape (pattern) formed on one of its main surfaces, and second conductive plates 123a and 123b formed on the other main surface. The insulating substrate 122 can be made of a material with excellent electrical insulation and thermal conductivity. Examples of materials for the insulating substrate 122 include Al2O3, AlN, and SiN. For high-voltage applications, materials that offer both electrical insulation and thermal conductivity are preferred, and while AlN and SiN can be used, the substrate is not limited to these. The first conductive plate 121 and the second conductive plates 123a and 123b can be made of metal materials such as Cu and Al, which have excellent processability. Furthermore, the conductive plates may be Cu or Al that have undergone treatment such as Ni plating for purposes such as rust prevention. Methods for arranging the conductive plates 121, 123a, and 123b on the insulating substrate 122 include direct copper bonding and active metal brazing. In the illustrated embodiment, two second conductive plates 123a and 123b are provided discontinuously on the insulating substrate 122, with one 123a functioning as an electrode joined to the SiC semiconductor element 11, and the other 123b functioning as an electrode connected to the lead frame 18.

[0044] The lead frame 18 is a conductive connecting member that connects the SiC semiconductor element 11 to the second conductive plate 123b, etc. Specifically, it is joined to the electrodes (surface electrodes) of the SiC semiconductor element 11 with a bonding layer 17 such as solder. It is also joined to the wiring portion of the second conductive plate 123b, etc., with a bonding layer 17 such as solder. The lead frame 18 may be made of a metal such as copper or a copper-containing alloy. A Ni or Ni alloy layer, or a Cr or Cr alloy layer may be formed on the surface of the lead frame 18 by a plating method or the like. In this case, the film thickness of the Ni or Ni alloy layer, or the Cr or Cr alloy layer can be about 20 μm or less. In addition to the lead frame, other conductive connecting members that can connect the SiC semiconductor element 11 to the second conductive plate 123b, etc., include pin-shaped take-up terminals and wires such as aluminum or copper used in wire bonding.

[0045] The heat sink 13 can be made of a metal with excellent thermal conductivity, such as copper or aluminum. Additionally, the heat sink 13 can be coated with Ni or a Ni alloy to prevent corrosion. The heat sink may also be a cooler with functions such as water cooling or air cooling.

[0046] The bonding layer 17 can be formed using lead-free solder. For example, Sn-Ag-Cu, Sn-Sb, Sn-Sb-Ag, Sn-Cu, Sn-Sb-Ag-Cu, Sn-Cu-Ni, and Sn-Ag systems can be used, but are not limited to these. Alternatively, the bonding layer can be formed using a connecting material containing minute metal particles, such as a sintered body of nanosilver particles.

[0047] Case 16 may be a thermoplastic resin such as polyphenylene sulfide (PPS) or polybutylene terephthalate (PBT).

[0048] In this embodiment, the components including the SiC semiconductor element 11, the laminated substrate 12, and conductive connecting members such as the lead frame 18 and aluminum wire 14 are also referred to as the sealed components. A sealing material consisting of a thermosetting resin sealing layer 20 is filled onto the sealed components. The thermosetting resin sealing layer 20 contacts the SiC semiconductor element 11, the laminated substrate 12, and the conductive connecting members, and covers the periphery of these sealed components. The thickness of the thermosetting resin sealing layer 20 varies depending on the shape of the module, but may be approximately 0.1 mm to 2 mm.

[0049] The thermosetting resin encapsulation layer 20 is a cured product of a thermosetting resin composition comprising a thermosetting resin main component, a curing agent, an ultraviolet absorber, and an inorganic filler, and optionally containing a curing accelerator and additives.

[0050] The thermosetting resin main component is not particularly limited, and examples include epoxy resins, phenolic resins, and maleimide resins that have heat resistance and high electrical insulation properties. Among these, epoxy resins having at least two epoxy groups in one molecule are particularly preferred because they have high dimensional stability, water resistance, chemical resistance, and electrical insulation properties. Specifically, it is preferable to use aliphatic epoxy resins, alicyclic epoxy resins, or mixtures thereof.

[0051] Aliphatic epoxy resins are defined as epoxy compounds in which the carbon atoms to which the epoxy group is directly bonded are carbon atoms that constitute an aliphatic hydrocarbon. Therefore, even compounds that contain aromatic rings in their main skeleton are classified as aliphatic epoxy resins if they satisfy the above conditions. Examples of aliphatic epoxy resins include, but are not limited to, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, cresol novolac type epoxy resins, and polyfunctional epoxy resins with three or more functions. These can be used individually or in mixtures of two or more types. Furthermore, naphthalene type epoxy resins and polyfunctional epoxy resins with three or more functions have high glass transition temperatures and are therefore also referred to as high heat-resistant epoxy resins. Heat resistance can be improved by including these high heat-resistant epoxy resins.

[0052] Alicyclic epoxy resins refer to epoxy compounds in which the two carbon atoms constituting the epoxy group constitute an alicyclic compound. Examples of alicyclic epoxy resins include, but are not limited to, monofunctional epoxy resins, bifunctional epoxy resins, and polyfunctional epoxy resins with three or more functions. Alicyclic epoxy resins can be used alone or by mixing two or more different alicyclic epoxy resins. Furthermore, when alicyclic epoxy resins are cured by mixing them with acid anhydride curing agents, the glass transition temperature increases, so high heat resistance can be achieved by mixing alicyclic epoxy resins with aliphatic epoxy resins.

[0053] The thermosetting resin main component used in the thermosetting resin encapsulation layer 20 may be a mixture of the above-mentioned aliphatic epoxy resin and alicyclic epoxy resin. The mixing ratio when mixing may be arbitrary, and the mass ratio of the aliphatic epoxy resin to the alicyclic epoxy resin may be about 2:8 to 8:2, but may also be about 3:7 to 7:3, and is not limited to a specific mass ratio. In a preferred embodiment, the thermosetting resin main component used in the thermosetting resin encapsulation layer 20 is a mixture of bisphenol A type epoxy resin and alicyclic epoxy resin in a mass ratio of 1:1 to 1:4.

[0054] When the mass of the matrix resin of the thermosetting resin encapsulation layer 20 is 100 parts by mass, it is preferable to include 0.1 to 10 parts by mass of ultraviolet absorber in the thermosetting resin encapsulation layer 20, and it is even more preferable from the viewpoint of reliability to include 1 to 5 parts by mass of ultraviolet absorber in the thermosetting resin encapsulation layer 20. In this embodiment, the matrix resin refers to a concept that includes the main component and curing agent of the thermosetting resin, but does not include inorganic fillers. The ultraviolet absorber is generally uniformly dispersed in the thermosetting resin encapsulation layer 20 within the above concentration range. However, within the above concentration range, it may be present at different concentrations depending on the part of the thermosetting resin encapsulation layer 20, and it is preferable that it is present at a higher concentration near the semiconductor element 11. In the first embodiment, it is preferable to include in the thermosetting resin encapsulation layer 20 an ultraviolet absorber having an OH group among the ultraviolet absorbers represented by general formulas (1), (2), and (3). This also provides the effect of improving adhesion when the thermosetting resin encapsulation layer 20 comes into contact with the conductive plate 123a or other components that make up the laminated substrate 12.

[0055] Next, the inorganic filler, which is an essential component of the thermosetting resin encapsulation layer 20, may be a metal oxide or metal nitride with high thermal conductivity and a low coefficient of thermal expansion. Examples include, but are not limited to, fused silica, silica (silicon oxide), alumina, aluminum hydroxide, titania, zirconia, aluminum nitride, talc, clay, mica, and glass fiber. These inorganic fillers can increase the thermal conductivity and reduce the coefficient of thermal expansion of the thermosetting resin encapsulation layer 20. Since the thermosetting resin encapsulation layer 20 preferably has electrical insulation properties, it is preferable that these inorganic fillers also have insulating properties. These inorganic fillers may be used individually or mixed in groups of two or more. Furthermore, the inorganic fillers may be microfillers or nanofillers, and it is also possible to mix two or more inorganic fillers with different particle sizes and / or types. In particular, it is preferable to use inorganic fillers with an average particle size of about 0.2 to 20 μm. The amount of inorganic filler added to the thermosetting resin encapsulation layer 20 is preferably 100 to 600 parts by mass, and more preferably 200 to 400 parts by mass, when the mass of the matrix resin is 100 parts by mass. If the amount of inorganic filler is less than 100 parts by mass, the coefficient of thermal expansion of the thermosetting resin encapsulation layer 20 may increase, making it prone to delamination and cracking. If the amount is greater than 600 parts by mass, the viscosity of the composition may increase, resulting in poor extrusion moldability.

[0056] The curing agent, which is an essential component of the thermosetting resin encapsulation layer 20, is not particularly limited as long as it can react with the thermosetting resin main component, preferably the epoxy resin main component, and cure, but it is preferable to use an acid anhydride-based curing agent. Examples of acid anhydride-based curing agents include aromatic acid anhydrides, specifically phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, etc. Alternatively, cyclic aliphatic acid anhydrides, specifically tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, etc., or aliphatic acid anhydrides, specifically succinic anhydride, polyadipic anhydride, polysebacic anhydride, polyazelaic anhydride, etc. The amount of curing agent to be blended is preferably 50 parts by mass or more and 170 parts by mass or less, and more preferably 80 parts by mass or more and 150 parts by mass or less, per 100 parts by mass of the epoxy resin main component. If the amount of curing agent is less than 50 parts by mass, the glass transition temperature may decrease due to insufficient crosslinking, and if it exceeds 170 parts by mass, it may result in a decrease in moisture resistance, high heat distortion temperature, and heat stability. When using bisphenol A type epoxy resin alone or a mixture of bisphenol A type epoxy resin and the high heat-resistant epoxy resin exemplified above as the main component of the thermosetting resin, it may be preferable not to use a curing agent, as this improves heat resistance. The blending ratio of the high heat-resistant epoxy resin may be, for example, 10% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 25% by mass or less, when the total mass of the main component of the thermosetting resin is 100%. Within this range, heat resistance is improved and viscosity does not increase, so it is preferable.

[0057] The thermosetting resin composition constituting the thermosetting resin encapsulation layer 20 may further contain a curing accelerator as an optional component. Suitable curing accelerators include imidazole or its derivatives, tertiary amines, boric acid esters, Lewis acids, organometallic compounds, organic acid metal salts, etc. The amount of curing accelerator added is preferably 0.01 parts by mass or more and 50 parts by mass or less, and more preferably 0.1 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the thermosetting resin main component.

[0058] The thermosetting resin composition constituting the thermosetting resin encapsulation layer 20 may also contain optional additives, to the extent that they do not impair its properties. Examples of additives include, but are not limited to, flame retardants, pigments for coloring the resin, plasticizers and silicone elastomers for improving crack resistance. These optional components and their amounts can be appropriately determined by a person skilled in the art, depending on the specifications required for the semiconductor device and / or the thermosetting resin encapsulation layer 20.

[0059] Next, a method for manufacturing the illustrated power semiconductor module will be described. A heat sink 13, a laminated substrate 12, and a SiC semiconductor element 11 are joined together, and a case 16 is attached to the heat sink 13. Then, a lead frame 18 is joined, and wire bonding is performed with aluminum wire 14. Next, a thermosetting resin composition constituting the thermosetting resin encapsulation layer 20 is injected into the case 16 and heat-cured. The heat-curing process can be performed in two stages, for example. When epoxy resin is used as the main thermosetting resin, it is heated at 90-120°C for 1-2 hours to achieve a semi-cured state (pre-curing). After that, heating can be further carried out at 175-185°C for 1-2 hours (full curing). Full curing can be performed by continuously increasing the temperature from pre-curing. However, it is not limited to a specific temperature or time, and there are cases where two-stage curing is not necessary. In pre-curing, it is preferable to slowly increase the heating rate from room temperature from 0.5°C / min to 2°C / min, as this improves the dispersibility of the ultraviolet absorber and improves the reliability of the module.

[0060] In a modified form of the illustrated power semiconductor module, the encapsulant may further include a primer layer. The primer layer can be formed at the interface between the encapsulated member, which includes the laminated substrate, semiconductor elements, and the conductive connecting member, and the thermosetting resin encapsulant layer 20. The primer layer may be preferably used at the interface between the thermosetting resin encapsulant layer 20 and the encapsulated member, as it has a stress-relieving effect and ensures adhesion. The primer layer may be a layer made of a resin containing polyamide, polyimide, or polyamideimide. A resin containing polyamide, polyimide, or polyamideimide is referred to as a primer material. Polyimide is a general term for polymer compounds containing imide bonds, and polymers having a cyclic imide structure are preferred. Specifically, examples include PMDA / 4,4'-ODA (polymer of pyromellitic dianhydride and oxydianiline), BPDA / PDA (polymer of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and paraphenylenediamine), and BPDA / 4,4'-ODA (polymer of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and oxydianiline), but the term is not limited to these. Furthermore, polyamide is a general term for polymer compounds containing amide bonds, and polyamideimide is a general term for polymer compounds containing both imide and amide bonds.

[0061] In the modified form of the first embodiment, the primer layer does not necessarily contain an ultraviolet absorber, but it may contain one. The thickness of the primer layer is not particularly limited as long as it is thick enough to provide adhesion. If an ultraviolet absorber is not included, the thickness of the primer layer can be, for example, about 1 to 20 μm, and is preferably 1 to 10 μm. Within this range, the primer layer also has a stress relaxation effect, which improves adhesion, making it more preferable. The primer layer can be provided so as to cover the entire surface of the SiC semiconductor element 11, the laminated substrate 12, the lead frame 18, and the aluminum wire 14 shown in Figure 1. In addition, inorganic fillers such as silica may be added to the primer layer for purposes such as adjusting the coefficient of thermal expansion. In that case, the average particle size of the inorganic filler may be 10 nm to 1000 nm, and the amount added is preferably 0.5 to 3 parts by mass per 100 parts by mass of primer material. This is because it does not hinder the stress relaxation effect.

[0062] In a further modification of the first embodiment, the encapsulant may further comprise one or more additional resin encapsulating layers other than the thermosetting resin encapsulating layer. For example, it may comprise a thermoplastic resin layer covering the surface of the thermosetting resin encapsulating layer 20 that comes into contact with the atmosphere. In this case as well, a primer layer may or may not be provided.

[0063] In the manufacturing method of a power semiconductor module equipped with a primer layer, the primer layer is formed after assembling the components to be sealed and before injecting the thermosetting resin composition constituting the thermosetting resin encapsulation layer 20. The primer layer can be applied to the entire surface of the components to be sealed, including the SiC semiconductor element 11, lead frame 18, laminated substrate 12, aluminum wire 14, and case 16 shown in Figure 1, by means of, for example, spray coating, immersion method, or application by dispenser. After the formation of the primer layer, it is preferable to heat it in an inert oven with nitrogen gas introduced in stages at 70 to 100°C for about 60 to 80 minutes, and then further heat it at 200 to 220°C for 60 to 80 minutes. This heating operation heats the Cu constituting the lead frame 18, vaporizes the solvent, and solidifies the primer. After the formation of the primer layer, insulating encapsulation with the thermosetting resin encapsulation layer 20 can be performed in the same manner as the manufacturing method of the power semiconductor module shown in Figure 1. If an additional resin encapsulation layer is optionally provided, the additional resin encapsulation layer can be formed by a conventional method.

[0064] The illustrated configuration of the power semiconductor module is an example, and the present invention is not limited to this configuration. For example, any conductive connecting member may be used, and implant pins may also be used. Furthermore, the conductive connecting member may consist only of a lead frame or only of wires. In a module where the conductive connecting member includes implant pins, if a primer layer is provided, the primer layer can also be formed on the surface of the implant pins. In a module where the conductive connecting member consists only of wires, if a primer layer is provided, the primer layer can also be formed on the surface of the wires.

[0065] Furthermore, a caseless power semiconductor module may also be used. While not shown in the diagram, a caseless power semiconductor module structure may include, for example, implant pins and a printed circuit board bonded to the implant pins, replacing the lead frame and aluminum wires in Figure 1, with these components sealed by a thermosetting resin encapsulation layer. The printed circuit board can be a polyimide film substrate or an epoxy film substrate with a conductive layer of Cu, Al, etc. Copper pins can be used as the implant pins. Both the conductive layer of the printed circuit board and the implant pins may be made of Cu or Al, treated with nickel plating or other processes for corrosion prevention. This printed circuit board and implant pins electrically connect semiconductor elements to each other, or between semiconductor elements and the laminated substrate. The implant pins and the laminated substrate or semiconductor elements can be joined by a solder joint layer. Additionally, by extending the implant pins from the laminated substrate to the outside of the thermosetting resin encapsulation layer, the implant pins can be used as external connection terminals. The manufacturing of a power semiconductor module in this manner involves assembling a encapsulated component including a laminated substrate, semiconductor elements, implant pins, and a printed circuit board; optionally forming a primer layer on the surfaces of the laminated substrate, semiconductor elements, implant pins, and printed circuit board by methods such as spray coating; then placing the encapsulated component in a suitable mold; and filling the mold with a thermosetting resin composition constituting the thermosetting resin encapsulation layer and curing it. Examples of molding methods for such encapsulated bodies include vacuum casting, transfer molding, liquid transfer molding, and potting, but are not limited to the specified molding method.

[0066] According to this embodiment, by making substantially the entire thermosetting resin encapsulation layer an ultraviolet absorption layer, it is possible to prevent the degradation of the encapsulation resin due to ultraviolet light without increasing the number of basic steps, which is an advantage.

[0067] [Second Embodiment] The semiconductor device according to the second embodiment includes a thermosetting resin encapsulation layer as the encapsulation material, the thermosetting resin encapsulation layer includes a first encapsulation layer that covers the periphery of a SiC semiconductor element and a second encapsulation layer that covers the first encapsulation layer, and the first encapsulation layer (ultraviolet absorption layer) includes a thermosetting resin main component, a curing agent, an inorganic filler, and an ultraviolet absorber. In other words, in the second embodiment, some of the multiple thermosetting resin encapsulation layers function as ultraviolet absorption layers.

[0068] Figure 2 shows a conceptual cross-sectional view of a power semiconductor module, which is an example of a semiconductor device according to a second embodiment of the present invention. In the illustrated power semiconductor module, a first sealing layer 21 is formed in contact with a encapsulated member such as a SiC semiconductor element 11, a laminated substrate 12, a lead frame 18, and an aluminum wire 14 which is a conductive connecting member, and a second sealing layer 22 is formed around it. That is, the sealing material is composed of a thermosetting resin sealing layer, and the thermosetting resin sealing layer includes the first sealing layer 21 and the second sealing layer 22. The SiC semiconductor element 11 is bonded to the first conductive substrate 123a of the laminated substrate 12 via a bonding layer 17 such as solder. Since ultraviolet light is mainly emitted from the side surface of the SiC element, the first sealing layer 21 may cover at least the side surface of the SiC semiconductor element 11 and cover the surface of the SiC semiconductor element 11. Alternatively, the first sealing layer 21 may cover the exposed end of the bonding layer 17 and be arranged in contact with the first conductive substrate 123a. When the first sealing layer 21 is in contact with the first conductive substrate 123a, from the viewpoint of adhesion, the length in contact with the first conductive substrate 123a is preferably 0.5 mm to 1.0 mm. The length in contact refers to the length from the exposed end of the bonding layer 17 in contact with the first conductive substrate 123a to the end of the first sealing layer 21 along the first conductive substrate 123a. In addition, the first sealing layer 21 may be covered so as to be in contact with the insulating substrate 122 of the laminated substrate 12.

[0069] In the embodiment shown in Figure 2, typically only the first encapsulation layer 21 is in contact with the SiC semiconductor element 11, and the second encapsulation layer 22 is not in contact with the SiC semiconductor element 11. The composition of the first encapsulation layer 21 may be the same as the composition of the thermosetting resin encapsulation layer 20 in the first embodiment. The thickness of the first encapsulation layer 21 is preferably 2 to 1000 μm, and more preferably 100 to 1000 μm. The layer thickness referred to here is the thickness of the coating layer when the first encapsulation layer 21 is applied to the side and front surfaces of the SiC semiconductor element 11. Furthermore, when the mass of the matrix resin of the first encapsulation layer 21 is 100 parts by mass, it is preferable to include 0.1 to 10 parts by mass of ultraviolet absorber in the first encapsulation layer 21, and more preferably 1 to 5 parts by mass of ultraviolet absorber in the first encapsulation layer 21 from the viewpoint of reliability. In this embodiment, the matrix resin refers to a concept that includes the main component and curing agent of the thermosetting resin, but does not include inorganic fillers. The ultraviolet absorber is generally uniformly dispersed in the first sealing layer 21 within the above concentration range. However, within the above concentration range, it may be present at different concentrations in different parts of the first sealing layer 21, and it is preferable that it be present at a higher concentration near the semiconductor element 11. Alternatively, the amount of ultraviolet absorber added may be the amount described in the first embodiment.

[0070] The first sealing layer 21 contacts a conductive member connected to the front surface of the SiC semiconductor element 11, such as a part of the lead frame 18. The lead frame 18 may or may not be covered. Conductive members such as lead frames are generally made of copper or aluminum, which do not transmit ultraviolet light generated by the SiC semiconductor element 11, so they do not need to be covered. In the second embodiment, it is preferable to include in the first sealing layer 21 an ultraviolet absorber having an OH group among the ultraviolet absorbers represented by general formulas (1), (2), and (3). This also has the effect of improving adhesion when the first sealing layer 21 comes into contact with the conductive plate 123a or other members constituting the laminated substrate 12.

[0071] The second sealing layer 22 contains a thermosetting resin main component, a curing agent, and an inorganic filler, and may contain no ultraviolet absorber or only a smaller amount than that of the first sealing layer 21. Furthermore, it is preferable that the thermosetting resin main component and curing agent of the second sealing layer 22 are the same as those of the first sealing layer 21. This is to ensure that the coefficients of thermal expansion of the first sealing layer 21 and the second sealing layer 22 are similar, thereby preventing interfacial delamination between the first sealing layer 21 and the second sealing layer 22. Also, for the same reason, it is preferable that the type and content of the inorganic filler in the second sealing layer 22 are the same as those of the inorganic filler in the first sealing layer 21.

[0072] In the second embodiment as well, a primer layer (not shown) may be provided between the first sealing layer 21 and the sealed member including the SiC semiconductor element 11, or between the second sealing layer 22 and the sealed member such as a laminated substrate. The composition and thickness of the primer layer may be the same as those exemplified in the first embodiment.

[0073] The method for manufacturing a semiconductor device according to the second embodiment can be carried out in the same manner as the first embodiment, except that in the sealing material formation step, the first sealing layer 21 is formed, and if necessary, the pre-curing step shown in the first embodiment is performed before forming the second sealing layer 22. Alternatively, the first sealing layer 21 may be formed, pre-cured, and then fully cured before forming the second sealing layer 22, pre-curing, and then fully curing. However, from the viewpoint of adhesion between the first sealing layer 21 and the second sealing layer 22, it is preferable to form the first sealing layer 21, perform the pre-curing step, then form the second sealing layer 22, pre-curing, and then fully curing. The method for forming the first sealing layer 21 may include, but is not limited to, spray coating or coating by a dispenser. Furthermore, the modified form of the semiconductor device according to the second embodiment may be the same as the modified form of the semiconductor device according to the first embodiment.

[0074] According to the semiconductor device of the second embodiment of the present invention, by providing a thermosetting resin encapsulation layer partially containing an ultraviolet absorber around the SiC semiconductor element, ultraviolet light can be efficiently absorbed with a small amount of ultraviolet absorber without impairing adhesion at each interface, thereby protecting the encapsulation resin. Since ultraviolet absorbers do not react well with thermosetting resins, especially epoxy resins, if the layer containing the ultraviolet absorber is large, areas of non-uniform dispersion may occur. According to the semiconductor device of the second embodiment of the present invention, since the layer containing the ultraviolet absorber (first encapsulation layer) is thin and small in quantity, it is presumed that a necessary and sufficient predetermined amount of ultraviolet absorber can be placed around the SiC semiconductor element.

[0075] [Third Embodiment] A semiconductor device according to the third embodiment is a semiconductor device in which a SiC semiconductor element mounted on a multilayer substrate and a conductive connecting member are sealed with a sealing material containing an ultraviolet absorber, wherein the sealing material comprises a primer layer and a thermosetting resin sealing layer, and the primer layer contains an ultraviolet absorber.

[0076] Figure 3 is a partial cross-sectional view of the area around a SiC semiconductor element in a power semiconductor module, which is an example of a semiconductor device according to the third embodiment of the present invention. In the illustrated power semiconductor module, a primer layer 23 is formed in contact with the SiC semiconductor element 11 and the encapsulated members such as the second conductive plate 123a and lead frame 18, and a thermosetting resin encapsulation layer 24 is formed around the primer layer 23. Specifically, the primer layer covers the encapsulated members having wiring members such as the SiC semiconductor element, the laminated substrate, and the lead frame 18. That is, the encapsulating material is composed of a primer layer 23 and a thermosetting resin encapsulation layer 24, and the primer layer 23 functions as an ultraviolet absorption layer.

[0077] In the embodiment shown in Figure 3, typically only the primer layer 23 is in contact with the SiC semiconductor element 11, and the thermosetting resin encapsulation layer 24 is not in contact with the SiC semiconductor element 11. The composition of the primer layer 23 is the same as the primer layer composition described as a modified form in the first embodiment, but further includes an ultraviolet absorber. When the matrix resin of the primer layer 23 is 100 parts by mass, it is preferable to include 0.1 to 5 parts by mass of ultraviolet absorber, and more preferably 0.5 to 2.0 parts by mass of ultraviolet absorber. In this embodiment, the matrix resin of the primer layer refers to a concept that includes the primer material but does not include inorganic fillers. The primer layer 23 may contain inorganic fillers to adjust the coefficient of linear expansion, but it is preferable not to include them. This is because if the primer layer contains inorganic fillers, the amount of ultraviolet absorber decreases accordingly, and the stress relaxation effect may also decrease. It is preferable to include ultraviolet absorbers having OH groups among the ultraviolet absorbers shown in general formulas (1), (2), and (3) in the primer layer 23. This also has the effect of improving the adhesion between the primer layer 23 and the conductive plate 123a that makes up the laminated substrate 12.

[0078] The thickness of the primer layer 23 is preferably 5 to 200 μm, and more preferably 10 to 100 μm. By setting the layer thickness within this range, it is possible to effectively absorb ultraviolet light generated by the SiC semiconductor element 11 while providing stress relaxation, thereby preventing deterioration of the thermosetting resin encapsulation layer 24.

[0079] The thermosetting resin encapsulation layer 24 comprises a thermosetting resin main component, a curing agent, and an inorganic filler, and may contain no UV absorber or only a smaller amount than that of the primer layer 23. The thermosetting resin main component, curing agent, and inorganic filler of the thermosetting resin encapsulation layer 24 can be selected from the same options as those for the thermosetting resin main component, curing agent, and inorganic filler contained in the thermosetting resin encapsulation layer 20 in the first embodiment. It may also contain any optional components of the thermosetting resin encapsulation layer 20 in the first embodiment.

[0080] According to the semiconductor device of the third embodiment of the present invention, by including an ultraviolet absorber in the primer layer, ultraviolet light can be efficiently absorbed with a small amount of ultraviolet absorber and the encapsulating resin can be protected without impairing adhesion at each interface or increasing the number of basic steps. Since the layer containing the ultraviolet absorber (primer layer) is thinner than the thermosetting resin encapsulating layer of the first embodiment, it is presumed that, similar to the second embodiment, a necessary and sufficient predetermined amount of ultraviolet absorber can be placed around the SiC semiconductor element. [Examples]

[0081] The present invention will be described in more detail below with reference to examples of the present invention. However, the present invention is not limited to the scope of the following examples.

[0082] 1. Manufacturing of semiconductor devices Power semiconductor modules according to the first, second, and third embodiments of the present invention were manufactured as Examples 1, 2, and 3, and their reliability was evaluated. The reliability was T j Power cycle endurance (T j The evaluation was based on P / C tolerance. The power cycle test was performed at 40~185℃ (ΔT j At 145°C, the number of cycles required for the electrical characteristics to reach abnormal values ​​was investigated, with each cycle consisting of 2 seconds of energized operation followed by 9 seconds of rest. Specifically, the system was energized from 40°C to 185°C. To understand the effects of ultraviolet light, the temperature was raised above the normal temperature (175°C) and the current flowing through the element was increased for evaluation. Note that more than 50,000 cycles are required to obtain sufficient reliability.

[0083] Epoxy resin was used as the thermosetting resin constituting the thermosetting resin encapsulation layer 20 in Example 1, the first encapsulation layer 21 and the second encapsulation layer 22 in Example 2, and the thermosetting resin encapsulation layer 24 in Example 3. Epoxy resin ME-276 (manufactured by Pernox Co., Ltd.) was used as the epoxy resin main component, and MV-138 (manufactured by Pernox Co., Ltd.) was added as an acid anhydride-based curing agent at a ratio of 121 parts by mass per 100 parts by mass of the main component. For the inorganic filler, spherical silica (manufactured by AGC Inc.) with an average particle size of 10 μm was used, and 270 parts by mass were added when the total mass of the epoxy resin main component and curing agent was 100 parts by mass. In the ultraviolet absorption encapsulation layers of Examples 1 and 2, ultraviolet absorbers at the concentrations shown in Table 1 were added to this matrix resin. The concentration is expressed in parts by mass per 100 parts by mass of the matrix resin.

[0084] In both Examples 1 and 2, a primer layer made of Hymar HL1200F (Showa Denko Materials), whose main component is polyamide, was formed on the laminated substrate, semiconductor element, lead frame, wire, and case. In Examples 1 and 2, no UV absorber was added to Hymar HL1200F. In Example 3, a UV absorber at the concentrations shown in Table 1 was added to the matrix resin made of Hymar HL1200F. The thickness of the primer layer is shown in each table.

[0085] A power semiconductor module of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the thermosetting resin encapsulation layer did not contain an ultraviolet absorber and a primer layer was not formed. Similarly, a power semiconductor module of Comparative Example 2 was manufactured in the same manner as in Example 3, except that the primer layer did not contain an ultraviolet absorber. The measurement results for the type of ultraviolet absorber, the thickness of the ultraviolet absorption layer (μm), the concentration of the ultraviolet absorber (parts by mass), and the P / C withstand rate (k cycles) are shown in Table 1. In Tables 2 to 7 below, the units of each physical quantity are the same as in Table 1. When an ultraviolet absorption layer was placed, the reliability could be improved by 1.5 to 2 times compared to the conventional case without an ultraviolet absorption layer. Furthermore, comparing the embodiments of Examples 1 to 3, it was found that the reliability of the modules in the second and third embodiments was slightly higher than that of the first embodiment. This is presumed to be because the ultraviolet absorber is uniformly distributed around the SiC semiconductor element that emits ultraviolet light.

[0086] [Table 1]

[0087] Next, in Example 2, power semiconductor modules of Examples 4 to 11 were manufactured in the same manner as in Example 2, except that the thickness of the first encapsulation layer (ultraviolet absorption layer) and the concentration of the ultraviolet absorber were changed. The thickness and composition of the primer layer were the same as in Example 2. The results are shown in Table 2. The thickness of the first encapsulation layer was good from 100 μm to 1000 μm. Furthermore, it was confirmed that the reliability was twice as high when the amount of ultraviolet absorber added was 0.1 parts by mass to 5 parts by mass compared to when there was no ultraviolet absorption layer. When the amount of addition increased to 7 parts by mass, the reliability tended to decrease slightly compared to when the amount of ultraviolet absorber added was lower. When the amount of ultraviolet absorber added was high and the ultraviolet absorption layer was thick, the reliability improved compared to the conventional method, but it decreased slightly compared to the case with the highest reliability.

[0088] [Table 2]

[0089] Next, in Example 3, power semiconductor modules of Examples 12 to 19 were manufactured in the same manner as in Example 3, except that the thickness of the primer layer (UV absorption layer) containing the UV absorber of the third embodiment and the concentration of the UV absorber in the primer layer were changed. The results are shown in Table 3. In Table 3, the unit of the primer layer thickness is μm. As shown in Table 3, it was found that the amount of UV absorber added to the primer layer is effective even when the primer layer is thin, with a minimum of 0.1 parts by mass, and reliability is particularly improved when the amount is between 1 and 5 parts by mass.

[0090] [Table 3]

[0091] Next, power semiconductor modules of Examples 20 to 27 were manufactured in the same manner as in Example 2, except that a different benzotriazole derivative was used as the UV absorber, and the effect of each type of UV absorber (improved reliability due to prevention of UV degradation) was evaluated. The thickness of the first sealing layer (UV absorbing layer), the thickness and composition of the primer layer were also the same as in Example 2. The results are shown in Tables 4 and 5. It was found that UV absorbers having an alkyl group in R2 or R4 of formula (1) are particularly preferred. Furthermore, for R2 or R4, bulky butyl groups are preferred over methyl groups with a small molecular weight, and a larger number of butyl groups is even more preferred. In other words, it is preferable for R2 or R4 to have a bulky functional group. Also, for R3 、 It was found that having an alkoxy group, specifically an octoxy group, is more preferable.

[0092] [Table 4]

[0093] [Table 5]

[0094] Next, power semiconductor joules of Examples 28-31 were manufactured in the same manner as in Example 2, except that a different benzophenone derivative was used as the ultraviolet absorber. The thickness of the first encapsulation layer (ultraviolet absorption layer), the thickness and composition of the primer layer were also the same as in Example 2. The results are shown in Table 6. In particular, R in formula (2) 13 , or R 14 It was found that the P / C tolerance is high when the group is an alkyl group or an alkoxy group, and that the alkoxy group is particularly preferred. Furthermore, it was found that methoxy groups and allyloxy groups are preferred among the alkoxy groups.

[0095] [Table 6]

[0096] Next, power semiconductor modules of Examples 32 to 38 were manufactured in the same manner as in Example 2, except that a different triazine derivative was used as the ultraviolet absorber. The thickness of the first encapsulation layer (ultraviolet absorption layer), the thickness and composition of the primer layer were also the same as in Example 2. The results are shown in Tables 7 and 8. In particular, R of formula (3) 21 , R 25 , R 28 Triazine derivatives having an alkyl group in any of the R groups are preferred. 21 , R 25 , R 28 Triazine derivatives having an alkoxy group in any of the components are even more preferred, and it was found that a larger number of alkoxy groups is preferable.

[0097] [Table 7]

[0098] [Table 8]

[0099] According to the present invention, by incorporating the ultraviolet absorption layer according to each embodiment, power cycle tolerance is improved, and a highly reliable semiconductor device can be provided. [Explanation of Symbols]

[0100] 11 SiC semiconductor device, 12 Multilayer substrate, 121 Conductive plate, 122 Insulating substrate 123a, b Conductive plate, 13 Heat sink, 14 Aluminum wire, 15 External terminal 16 cases, 17 bonding layers, 18 lead frames 20 Thermosetting resin encapsulation layer (ultraviolet absorption layer) 21 First sealing layer (ultraviolet absorption layer), 22 Second sealing layer 23 Primer layer (UV absorption layer), 24 Thermosetting resin encapsulation layer

Claims

1. A semiconductor device comprising a SiC semiconductor element mounted on a multilayer substrate and a conductive connecting member, sealed with a sealing material containing an ultraviolet absorber, The UV absorber is dispersed in particulate form, the average particle size of the UV absorber is 10 nm to 5000 nm, and the sealing material is (1) It consists of a thermosetting resin encapsulation layer containing a thermosetting resin main component, a curing agent, an inorganic filler, and an ultraviolet absorber. The ultraviolet absorber is dispersed in the thermosetting resin encapsulation layer. The thermosetting resin main component is selected from epoxy resin, phenolic resin, and maleimide resin main components; or (2) comprising a first thermosetting resin encapsulation layer that covers the periphery of a SiC semiconductor element, and a second thermosetting resin encapsulation layer that covers the first thermosetting resin encapsulation layer, The first thermosetting resin encapsulation layer comprises a thermosetting resin main component, a curing agent, and an ultraviolet absorber, and has a layer thickness of 100 to 1000 μm. The thermosetting resin main component is selected from epoxy resin, phenolic resin, and maleimide resin main components; or (3) The sealing material includes a thermosetting resin sealing layer, and the thermosetting resin sealing layer includes a thermosetting resin main component, a curing agent, an inorganic filler, and an ultraviolet absorber. The semiconductor device further includes a primer layer that covers the SiC semiconductor element and the conductive connecting member, and the primer layer is coated on the thermosetting resin encapsulation layer. The primer layer contains an ultraviolet absorber, The UV absorbers in question are 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, 1-hydroxy-6-(trifluoromethyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-hydroxy-4-methylbenzophenone, 4 Selected from -(allyloxy)benzophenone, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris(2,4-dihydroxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-n-octyloxyphenyl)-1,3,5-triazine, and 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine. Semiconductor equipment.

2. The sealing material is (1) or (2), and the ultraviolet absorber is 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-4-octoxyphenyl)benzotriazole, 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, 1-hydroxy-6-(trifluoromethyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-hydroxy-4-methylbenzopheno A semiconductor device according to claim 1, selected from n, 4-(allyloxy)benzophenone, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris(2,4-dihydroxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-n-octyloxyphenyl)-1,3,5-triazine, and 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine.

3. The semiconductor device according to claim 1, wherein the thermosetting resin main component comprises an epoxy resin main component.

4. The semiconductor device according to claim 1, wherein the sealing material is (3), the primer layer comprises one or more resins selected from polyamide resin, polyimide resin and polyamideimide resin, and the primer layer has a layer thickness of 5 to 200 μm.

5. The semiconductor device according to claim 1, wherein the sealing material is (1), the average particle size of the inorganic filler is 0.2 to 20 μm, and the average particle size of the ultraviolet absorber is smaller than the average particle size of the inorganic filler.

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