Semiconductor sealing resin sheet, resin-sealed semiconductor device, and method for manufacturing same

Abstract

A semiconductor sealing resin sheet according to the present disclosure contains (A) an epoxy resin, (B) a phenolic resin curing agent, (C) a curing accelerator, and (D) an inorganic filler, wherein the inorganic filler (D) is contained in an amount of 60.0 to 87.0 mass% and has a cumulative volume 50% particle diameter (D50) of 0.3 to 5.0 μm.

Description

Semiconductor Encapsulation Resin Sheet, Resin-Encapsulated Semiconductor Device, and Method for Manufacturing the Same

[0001] The present disclosure relates to a semiconductor encapsulation resin sheet, a resin-encapsulated semiconductor device using the same, and a method for manufacturing the same.

[0002] In recent years, with the spread of mobile devices, wearable devices, and the like, the miniaturization and thinning of semiconductor devices used in these devices have been progressing. Furthermore, the need for higher functionality and higher integration of various devices is also increasing. In high-performance computers and artificial intelligence (AI) devices, etc., it is necessary to integrate more functions into a small semiconductor chip.

[0003] In addition, in computers, smartphones, data centers, etc., an improvement in data processing speed is also required. As a memory technology for this purpose, HBM (High Bandwidth Memory) has attracted attention. HBM stacks a plurality of DRAM (Dynamic Random Access Memory) chips in three dimensions (3D) and connects them using technologies such as a silicon interposer and through-silicon vias (TSVs), thereby providing a higher bandwidth than conventional memories. This 3D implementation is a structure in which silicon wafers and semiconductor chips are stacked, and the filling property and connection reliability of an extremely narrow gap are important.

[0004] In recent years, in addition to 3D implementation, the adoption of a technology called 2.5-dimensional (2.5D) implementation has also been progressing. 2.5D implementation is a structure in which a plurality of semiconductor chips (for example, GPU (Graphics Processing Unit), HBM, etc.) are arranged side by side on a silicon interposer, and these are mounted on a substrate and interconnected with fine wiring. 2.5D implementation has the advantages of good heat dissipation and the ability to reduce the complexity of the manufacturing process. In addition, since the distance between chips is short and high-speed and wide-band communication is possible, it is rapidly spreading in fields that require large-capacity and low-latency data transfer, such as high-performance GPUs, AI accelerators, and network processors.

[0005] On the other hand, encapsulants for semiconductor components require properties such as high thermal conductivity and high insulation to improve the reliability of devices with precise structures. To improve the manufacturing efficiency of semiconductor devices, there is a shift from liquid resins to resin sheets as encapsulants are easier to mold and process.

[0006] For example, Patent Document 1 proposes a sealing resin sheet with a high silica filler content and reduced warping. Patent Document 2 also describes a sealing resin sheet (sealing film) containing an elastomer and with reduced warping.

[0007] Japanese Patent Publication No. 2014-36097, International Publication No. 2016 / 125350

[0008] The semiconductor encapsulating resin sheet of this disclosure comprises (A) epoxy resin, (B) phenolic resin curing agent, (C) curing accelerator, and (D) inorganic filler, wherein the inorganic filler (D) has a content of 60.0 to 87.0% by mass and a cumulative volume 50% particle size (D50) of 0.3 to 5.0 μm. In the resin-encapsulated semiconductor device of this disclosure, semiconductor elements fixed on a substrate are encapsulated with a cured product of the semiconductor encapsulating resin sheet. The method for manufacturing the resin-encapsulated semiconductor device of this disclosure includes a step of curing the semiconductor encapsulating resin sheet using the semiconductor encapsulating resin sheet by compression molding, lamination molding, or oven molding to encapsulate semiconductor elements.

[0009] This is a schematic cross-sectional view of a resin-encapsulated chip sample used for evaluation in the example. This is a schematic cross-sectional view of a PBGA (plastic ball grid array) package sample used for evaluation in the example.

[0010] In sealing resin sheets using large particle-diameter fillers, as described in Patent Document 1, for example, very narrow gaps (e.g., on the order of 10 μm), such as between DRAMs in an HBM, may not be adequately filled with the sealing material, resulting in voids that could degrade the performance and reliability of the device. Furthermore, even when using elastomers, as described in Patent Document 2, it was uncertain whether the sealing material could adequately fill narrow gaps.

[0011] This disclosure is based on the discovery that by forming a semiconductor encapsulation resin using a predetermined inorganic filler into a sheet, the encapsulant can be filled into narrow gaps well, and the warping of the encapsulated semiconductor package can be reduced. The semiconductor encapsulation resin sheet of this disclosure is easy to handle, and by using it, highly reliable resin-encapsulated semiconductor devices can be easily provided.

[0012] The present disclosure will be described in detail below with reference to one embodiment. The definitions and meanings of terms and notations used in this disclosure are shown below. The notation "X to Y" (where X and Y are numerical values) means a numerical range with X as the lower limit and Y as the upper limit. In a numerical range (for example, a range of content, etc.), the lower and upper limits described in steps may be combined independently of each other. The lower and upper limits of the numerical range may be replaced with the numerical values ​​described in the examples. The epoxy equivalent is a value measured in accordance with the potentiometric titration method specified in JIS K 7236:2001. The hydroxyl group equivalent is a value obtained from the hydroxyl value measured in accordance with the potentiometric titration method specified in JIS K 0070:1992. The particle diameter at 10% cumulative volume (D10), 50% cumulative volume (D50), and 90% cumulative volume (D90) refer to the particle diameters at which the cumulative volume from the smallest particle diameter side reaches 10%, 50%, and 90% respectively, in a volume-based particle size distribution measured by a laser diffraction scattering particle size distribution analyzer, unless otherwise specified.

[0013] [Semiconductor Encapsulation Resin Sheet] The semiconductor encapsulation resin sheet of this disclosure (hereinafter also simply referred to as the encapsulation resin sheet) comprises (A) epoxy resin, (B) phenolic resin curing agent, (C) curing accelerator, and (D) inorganic filler, wherein the inorganic filler content is 60.0 to 87.0% by mass and the cumulative volume 50% particle size (D50) is 0.3 to 5.0 μm. By including a predetermined amount of small-particle-diameter inorganic filler, the encapsulation resin sheet of this disclosure enhances the packing ability of the encapsulating material into narrow gaps, reduces warping of the encapsulated semiconductor package, and makes it easier to handle.

[0014] ((A) Epoxy resin) The epoxy resin (A) used in the sealing resin sheet of this disclosure may be any compound having two or more epoxy groups in one molecule, and its molecular weight and molecular structure are not particularly limited.

[0015] (A) The epoxy resin may be liquid, solid, or semi-solid at 25°C, and may be crystalline or amorphous. Here, "semi-solid" refers to a state in which it maintains its shape while being fluid, and deforms when external force is applied. Crystalline epoxy resin is an epoxy resin that has a crystalline structure below its melting point, and when heated and melted, the crystalline structure collapses, causing a rapid decrease in viscosity, and exhibits good fluidity during molding even in a highly filled state.

[0016] (A) Examples of epoxy resins include biphenyl type, cresol novolac type, phenol novolac type, bisphenol A type, bisphenol F type, bisphenol S type, dicyclopentadiene modified phenol type, trisphenolmethane type, triazine nucleus-containing type and other heterocyclic types, stilbene type, naphthalene type, condensed ring aromatic hydrocarbon modified type, and alicyclic type epoxy resins. These may be used individually or in combination of two or more types.

[0017] (A) The epoxy resin may have low viscosity and high fluidity from the viewpoint of good filling of the sealant into narrow gaps. (A) The epoxy resin may be liquid, semi-solid, or crystalline at 25°C from the viewpoint of ease of processing into a sheet.

[0018] (A) The epoxy resin may contain a compound represented by the following formula (1).

[0019]

[0020] In equation (1), n ​​is an integer from 1 to 20, and may also be an integer from 1 to 15, or an integer from 1 to 10. A is independently of (CH ２ ) ｒThere, r is an integer from 1 to 100, and may also be an integer from 1 to 50, or an integer from 1 to 20, or an integer from 1 to 10. B is independently of CH ２ or C(CH ３ ) ２ That is the case.

[0021] The compound represented by formula (1) may be liquid, semi-solid, or crystalline at 25°C. Using the compound represented by formula (1) makes it easier to process the epoxy resin composition into a sheet and to obtain a flexible cured product. Therefore, it is possible to reduce the warping of the cured encapsulating resin sheet.

[0022] The compound represented by formula (1) may have an epoxy equivalent of 200 to 1400 g / eq, 400 to 1200 g / eq, or 500 to 1000 g / eq, from the viewpoint of reducing the warping of the cured product of the sealing resin sheet.

[0023] (A) The epoxy resin may include crystalline epoxy resin from the viewpoint of good filling of the sealant into the narrow gap. (A) When the epoxy resin includes crystalline epoxy resin, the reliability of the sealed semiconductor device is likely to be improved.

[0024] (A) The epoxy resin may contain a compound represented by the following formula (2).

[0025]

[0026] The compound represented by formula (2) is a biphenyl-type epoxy compound that is solid at 25°C and crystalline. By using the compound represented by formula (2), it is easier to obtain a cured product with a high coefficient of thermal expansion and elastic modulus. Therefore, if the substrate of the semiconductor package to be encapsulated is prone to warping, it is possible to make it easier to correct the warping. When using the compound represented by formula (2) to reduce the warping of the cured product of the encapsulating resin sheet, the (E) low-elasticity agent described later may be used in combination.

[0027] The compound represented by formula (2) has a low melt viscosity, and using it tends to improve the packing performance of the sealant into narrow gaps. The compound represented by formula (2) may have a melt viscosity of 0.1 Pa·s or less at 150°C, 0.005 to 0.05 Pa·s, or 0.01 to 0.03 Pa·s. The melt viscosity is measured using a cone-plate viscometer (rotor angle 1°, shear rate 125s). －１ This is the value measured using ).

[0028] (A) The epoxy resin may contain either the compound represented by formula (1) or the compound represented by formula (2), or it may contain both.

[0029] (A) If the epoxy resin contains the compound represented by formula (1), the proportion of the compound represented by formula (1) in 100% by mass of the epoxy resin (A) may be 50.0 to 100% by mass, 60.0 to 100% by mass, or 70.0 to 100% by mass, from the viewpoint of reducing warpage of the cured product of the sealing resin sheet. (A) If the epoxy resin does not contain the compound represented by formula (1) but contains the compound represented by formula (2), the proportion of the compound represented by formula (2) in 100% by mass of the epoxy resin (A) may be 50.0 to 100% by mass, 60.0 to 100% by mass, or 70.0 to 100% by mass, from the viewpoint of good filling of the sealing material into narrow gaps. (A) The compound represented by formula (1) may be 100% by mass, or the compound represented by formula (2) may be 100% by mass.

[0030] (A) When the epoxy resin contains a compound represented by formula (1) and a compound represented by formula (2), it is easy to obtain a sealing resin sheet in which the effect of reducing the warping of the cured sealing resin sheet by the compound represented by formula (1) and the effect of improving the filling of the sealing material into narrow gaps by the compound represented by formula (2) are balanced. In this case, the proportion of the compound represented by formula (1) in 100% by mass of epoxy resin (A) may be 5.0 to 95.0% by mass, 10.0 to 90.0% by mass, or 20.0 to 80.0% by mass, and the proportion of the compound represented by formula (2) may be 5.0 to 95.0% by mass, 10.0 to 90.0% by mass, or 20.0 to 80.0% by mass. The total of the compound represented by formula (1) and the compound represented by formula (2) in 100% by mass of epoxy resin (A) may be 100% by mass.

[0031] (A) The epoxy resin may contain an epoxy resin that is semi-solid at 25°C, from the viewpoint of making it easier to process the epoxy resin composition into a sheet. (A) The compound represented by formula (1) in the epoxy resin may be in a semi-solid state at 25°C.

[0032] The content of epoxy resin (A) in the sealing resin sheet may be 8.0 to 45.0% by mass, 10.0 to 40.0% by mass, or 12.0 to 35.0% by mass, from the viewpoint of ease of handling of the sealing resin sheet and good curability.

[0033] (B) Phenolic Resin Curing Agent The (B) phenolic resin curing agent used in the sealing resin sheet of this disclosure is a compound having a phenolic hydroxyl group that can cure the (A) epoxy resin by reaction with the epoxy group of the (A) epoxy resin. The (B) phenolic resin curing agent may be a compound having two or more phenolic hydroxyl groups that can react with epoxy groups in one molecule, and its molecular weight and molecular structure are not particularly limited.

[0034] (B) Examples of phenol resin curing agents include novolac-type phenol resins such as phenol novolac-type and cresol novolac-type, which are obtained by reacting phenols such as phenol and alkylphenol with formaldehyde or paraformaldehyde. Other examples include modified phenol resins such as dicyclopentadiene-modified and paraxylene-modified phenol resins, phenol aralkyl-type phenol resins, biphenyl aralkyl-type phenol resins, trisphenolmethane-type phenol resins, and Zyloc-type (xylylene-type) phenol resins. These may be used individually or in combination of two or more.

[0035] The content of (B) phenol resin curing agent in the sealing resin sheet may be 0.1 to 12.0% by mass, 0.2 to 10.0% by mass, or 0.5 to 8.0% by mass, from the viewpoint of ease of handling of the sealing resin sheet and good curability.

[0036] (B) The phenol resin curing agent may have a hydroxyl group equivalent of 50 to 400 g / eq, 70 to 300 g / eq, or 90 to 250 g / eq, in view of the appropriate curability of the sealing resin sheet. (B) The content of the phenol resin curing agent may be such that, from the viewpoint of reducing the tack of the sealing resin sheet and ensuring good flexibility of the cured product of the sealing resin sheet, the amount of hydroxyl groups of (B) the phenol resin curing agent is 0.3 to 1.5 moles, 0.4 to 1.3 moles, or 0.5 to 1.2 moles per mole of epoxy groups of (A) epoxy resin.

[0037] (C) Curing accelerators (C) are used to appropriately accelerate the curing of the sealing resin sheet and to facilitate molding. Examples of (C) curing accelerators include 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 1,2-dimethylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 4-methylimidazole, 4-ethylimidazole, 2-phenyl-4-hydroxymethylimidazole, 2-ethyl-4-methylimidazole, 2- Imidazole compounds such as phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, and 1-cyanoethyl-2-phenylimidazole; 1,8 Examples include diazabicyclo compounds and their salts such as -diazabicyclo[5.4.0]undecene-7 (DBU), 1,5-diazabicyclo[4.3.0]nonene, and 5,6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene-7; tertiary amines such as triethylamine, triethylenediamine, benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; and organic phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, diphenylphosphine, triphenylphosphine, tri(p-methylphenyl)phosphine, tri(nonylphenyl)phosphine, methyldiphenylphosphine, dibutylphenylphosphine, tricyclohexylphosphine, bis(diphenylphosphino)methane, and 1,2-bis(diphenylphosphino)ethane. These may be used individually or in combination of two or more.

[0038] The content of the (C) curing accelerator in 100% by mass of the encapsulating resin sheet may be 0.1 to 5.0% by mass, may be 0.15 to 4.0% by mass, or may be 0.2 to 3.0% by mass from the viewpoints of an appropriate curing acceleration effect of the encapsulating resin sheet and good filling property of the encapsulating material into a narrow gap.

[0039] ((D) Inorganic filler) By including the (D) inorganic filler, the encapsulating resin sheet is easy to handle, and the epoxy resin composition before molding of the encapsulating resin sheet has an appropriate viscosity. In addition, the cured product of the encapsulating resin sheet tends to have high strength, low moisture absorption, and high thermal conductivity. The material of the (D) inorganic filler may be one generally used for resin compositions for encapsulating material applications, and examples include inorganic oxides such as fused silica, crystalline silica, crushed silica, synthetic silica, alumina, titanium oxide, and magnesium oxide; inorganic hydroxides such as aluminum hydroxide and magnesium hydroxide; and inorganic nitrides such as boron nitride, aluminum nitride, and silicon nitride. These may be used alone or in combination of two or more. The (D) inorganic filler may be silica, may contain fused silica, may contain spherical fused silica, or may contain alumina from the viewpoints of good moldability and easy handling of the encapsulating resin sheet.

[0040] The (D) inorganic filler has a D50 of 0.3 to 5.0 μm, may be 0.5 to 3.0 μm, or may be 0.8 to 1.2 μm. If the D50 is 0.3 μm or more, the fluidity of the epoxy resin composition before molding of the encapsulating resin sheet tends to be good, and the moldability and handling property of the encapsulating resin sheet tend to be good. Also, if the D50 is 5.0 μm or less, the encapsulating resin sheet has an appropriate tack and the handling property tends to be good. The maximum particle diameter of the (D) inorganic filler may be 45.0 μm or less, may be 30.0 μm or less, or may be 15.0 μm or less from the viewpoint of good filling property of the encapsulating material into a narrow gap.

[0041] (D) The inorganic filler may have a ratio of D90 to D10 (D90 / D10) of 1.5 to 25.0, 1.8 to 20.0, or 2.0 to 15.0. D90 / D10 is an indicator of the spread of the particle size distribution, i.e., the variation in particle size. A smaller value indicates less variation in particle size, and a larger value indicates greater variation in particle size. When D90 / D10 is within the above numerical range, the fluidity of the epoxy resin composition before molding of the sealing resin sheet tends to be good, the filling of the sealing material into narrow gaps tends to be good, and the warping of the sealed semiconductor package tends to be reduced.

[0042] The content of (D) inorganic filler in 100% by mass of the sealing resin sheet may be 60.0 to 87.0% by mass, 64.0 to 85.0% by mass, or 70.0 to 80.0% by mass. If the content is 60.0% by mass or more, the sealing resin sheet will have appropriate tack and will be easy to handle. If the content is 87.0% by mass or less, the fluidity of the epoxy resin composition before molding the sealing resin sheet will be good, and the moldability and handling of the sealing resin sheet will be good.

[0043] (E) Low-elasticity agent The encapsulating resin sheet may contain (E) a low-elasticity agent. The (E) low-elasticity agent can reduce the elastic modulus of the cured product of the encapsulating resin sheet and relieve internal stress. In particular, if the cured product of the encapsulating resin sheet is prone to warping, the addition of the (E) low-elasticity agent can reduce warping due to differences in thermal expansion and external forces. The (E) low-elasticity agent may be, for example, a stress-reducing agent such as silicone oil or liquid rubber, or a flexibility-imparting agent such as a thermoplastic elastomer. The (E) low-elasticity agent may be used alone or in combination of two or more types.

[0044] (E) The content of the low-elasticity agent may be an amount within a range that does not impair the good moldability of the encapsulating resin sheet, the good filling property of the encapsulating material into the narrow gap, and the ease of handling of the encapsulating resin sheet. The content of the (E) low-elasticity agent in 100% by mass of the encapsulating resin sheet may be 0 to 20.0% by mass, may be 0 to 18.0% by mass, or may be 0 to 15.0% by mass.

[0045] (Other Components) In addition to the components described above, the encapsulating resin sheet of the present disclosure may be appropriately added with additives such as coupling agents such as epoxy silane-based, amino silane-based, ureido silane-based, vinyl silane-based, alkyl silane-based, organic titanate-based, and aluminum alkoxide-based according to the physical property requirements of the encapsulating mode of semiconductor components; colorants such as carbon black and cobalt blue; ion scavengers such as hydrotalcite; and mold release agents such as synthetic wax, natural wax, higher fatty acids, and metal salts thereof. The additives may be used alone or in combination of two or more.

[0046] The total content of the additives in the encapsulating resin sheet may be an amount within a range that does not inhibit the filling property of the encapsulating material into the narrow gap, the effect of reducing the warpage of the encapsulated semiconductor package, and the ease of handling of the encapsulating resin sheet, and may be 0 to 3.0% by mass, may be 0 to 2.5% by mass, or may be 0 to 2.0% by mass.

[0047] (Manufacturing Method) The epoxy resin composition before molding of the encapsulating resin sheet of the present disclosure can be obtained by mixing the components (A) to (D), the component (E) as necessary, and additives as other components as optional components. For example, after blending each component and sufficiently mixing with a mixer or the like, it can be obtained by melt-kneading with a kneading device such as a hot roll or a kneader and then cooling.

[0048] The sealing resin sheet of this disclosure is obtained by heating and softening the epoxy resin composition prepared as described above, for example, at 60 to 120°C, and forming it into a sheet. Specifically, the epoxy resin composition may be sandwiched between heat-resistant release films such as polyester films, and then rolled while heated between rolls to form the sheet. Alternatively, the epoxy resin composition may be supplied onto the release film to form a resin layer of substantially uniform thickness, and then, if necessary, another release film may be placed on top of the resin layer, and the resin layer may be heat-pressed to form the sheet.

[0049] After performing the molding described above, a sealing resin sheet with a release film is obtained by cooling to room temperature (approximately 25°C). The sealing resin sheet may retain the release film until it is used for semiconductor encapsulation. The sealing resin sheet may also contain a B-staged epoxy resin composition.

[0050] The sealing resin sheet of this disclosure is used for sealing semiconductor components, and because it has good filling properties for sealing material into narrow gaps and reduces warping of the sealed semiconductor package, it may be used for mold underfill or for HBM.

[0051] The sealing resin sheet may be molded to a desired thickness or cut to a desired size and shape, depending on the size and form of the semiconductor component to be sealed. The thickness of the sealing resin sheet may be, for example, 0.05 to 2.0 mm, from the viewpoint of ease of handling and filling of the sealing material. The size and shape of the sealing resin sheet may be, for example, a rectangle of 50 mm x 50 mm to 600 mm x 600 mm, or a circle with a diameter of 50 to 450 mm.

[0052] [Resin-Sealed Semiconductor Device] The resin-sealed semiconductor device of the present disclosure has semiconductor elements fixed on a substrate that are sealed with a cured product of the sealing resin sheet of the present disclosure described above.

[0053] The semiconductor elements encapsulated in a resin-encapsulated semiconductor device are not particularly limited and include, for example, integrated circuits (ICs), large-scale integrated circuits (LSIs), diodes, thyristors, transistors, etc. The substrate is not particularly limited and may be one commonly used for fixing semiconductor elements, or it may be a wafer such as a silicon wafer.

[0054] The sealing resin sheet of this disclosure has good filling properties for the sealing material into narrow gaps, reduces warping of the sealed semiconductor package, and has good handling properties. Therefore, the semiconductor element to be sealed may be formed by through-silicon vias (TSVs) or flip-chip bonding. Even with such semiconductor elements, by using the sealing resin sheet of this disclosure, a resin-sealed semiconductor device with high reflow resistance, humidity resistance, and high-temperature storage reliability can be obtained.

[0055] [Method for Manufacturing a Resin-Sealed Semiconductor Device] The method for manufacturing a resin-sealed semiconductor device according to the present disclosure includes a step of sealing a semiconductor element using the semiconductor sealing resin sheet of the present disclosure described above by compression molding, lamination molding, or oven molding. By going through a sealing step using such a molding method, the sealing resin sheet adheres closely to the semiconductor element, the filling of the sealing material is easily improved, and a resin-sealed semiconductor device with high reflow resistance, humidity resistance reliability, and high-temperature storage reliability can be easily obtained.

[0056] The manufacturing method disclosed herein is particularly useful for 3D mounting in which multiple semiconductor elements are stacked on a large-area substrate, such as a square with a encapsulation size of 300 mm x 300 mm or a circle with a diameter of 300 mm, using TSV or flip-chip bonding. It is also useful for 2.5D mounting on similar substrates.

[0057] Compression molding is performed, for example, by placing a sealing resin sheet in a mold over a substrate on which semiconductor elements are mounted, and then applying heat and pressure. Compression molding can accommodate various package shapes and is advantageous in terms of cost. The molding temperature may be 100 to 190°C, and the pressure may be 0.1 to 12 MPa.

[0058] Lamination molding can be done using methods such as roller molding or diaphragm molding. Diaphragm molding is also suitable because it allows for good filling of the sealing material into narrow gaps. Lamination molding has less variation in the sealing state and is advantageous for thin packages. The molding temperature may be 100 to 190°C, and the pressure may be 0.1 to 12 MPa.

[0059] Oven molding is performed, for example, by placing a sealing resin sheet in a mold over a substrate on which semiconductor elements are mounted, placing the substrate in an oven, reducing the pressure inside the oven and heating under vacuum, then opening to the atmosphere, and further pressurizing if necessary. Oven molding tends to result in good filling even for semiconductor elements with complex shapes. The molding temperature may be 100 to 190°C, and the pressurizing pressure may be 0.5 to 1.5 MPa.

[0060] After each of the above molding processes, the sealing resin sheet (sealant) may be post-cured. Post-curing may be performed by heating at 130 to 190°C for 2 to 8 hours.

[0061] Next, the present disclosure will be specifically described by examples. The present disclosure is not limited in any way by these examples.

[0062] [Examples 1-28 and Comparative Examples 1-10] Raw materials were added to a universal mixer heated to 80-130°C according to the respective compositions of the Examples and Comparative Examples shown in Tables 1-4, kneaded, and then cooled to room temperature (25°C) to obtain epoxy resin compositions. The obtained epoxy resin compositions were sandwiched between polyester release films and rolled at a speed of 0.5 m / min between rolls at 80°C to produce sealing resin sheets of a predetermined thickness.

[0063] Details of the raw materials used in the examples and comparative examples are shown below. <(A) Epoxy resin> ・A1: "jER (registered trademark) YX7110", manufactured by Mitsubishi Chemical Corporation; epoxy equivalent 1000 g / eq, semi-solid, corresponds to formula (1) (n=1 to 10, r=1 to 20) ・A2: "jER (registered trademark) YX7105", manufactured by Mitsubishi Chemical Corporation; epoxy equivalent 500 g / eq, liquid, corresponds to formula (1) (n=1 to 5, r=1 to 3) ・A3: "EPICLON (registered trademark) EXA-4816", manufactured by DIC Corporation; epoxy equivalent 400 g / eq, liquid ・A4: "EPICLON (registered trademark) EXA-4850-150", manufactured by DIC Corporation; epoxy equivalent 450 g / eq, liquid ・A5: "Epomic (registered trademark) A6: "R140P", manufactured by Mitsui Chemicals, Inc.; epoxy equivalent 188 g / eq, diglycidyl ether of bisphenol A with epichlorohydrin, liquid. A7: "jER (registered trademark) YX4000HK", manufactured by Mitsubishi Chemical Corporation; epoxy equivalent 193 g / eq, biphenyl type, solid, melt viscosity at 150°C 0.015 Pa·s, corresponds to formula (2). A8: "CNE200ELB", manufactured by Changchun Artificial Resin Factory Co., Ltd.; epoxy equivalent 198 g / eq, o-cresol novolac type, solid. A9: "NC-3000", manufactured by Nippon Kayaku Co., Ltd.; epoxy equivalent 273 g / eq, biphenyl aralkyl type, solid. Note that the properties of the epoxy resin are those at 25°C.

[0064] <(B) Phenolic Resin Curing Agents> ・B1: "H-4", manufactured by UBE Corporation; hydroxyl group equivalent 105 g / eq, phenol novolac type ・B2: "MEHC-7800M", manufactured by UBE Corporation; hydroxyl group equivalent 174 g / eq, Zyloc type ・B3: "MEHC-7851S", manufactured by UBE Corporation; hydroxyl group equivalent 209 g / eq, biphenyl aralkyl type ・B4: "MEH-7500", manufactured by UBE Corporation; hydroxyl group equivalent 97 g / eq, trisphenolmethane type

[0065] <(C) Curing accelerator> ・C1: "2P4MHZ-PW", manufactured by Shikoku Chemicals, Inc.; 2-phenyl-4-methyl-5-hydroxymethylimidazole ・C2: "PP-200", manufactured by Hokko Chemical Industry Co., Ltd.; triphenylphosphine ・C3: "U-CAT (registered trademark) SA841", manufactured by Sunapro Co., Ltd.; phenol novolac resin salt of 1,8-diazabicyclo[5.4.0]-7-undecene (DBU)

[0066] <(D) Inorganic Fillers> ・D1: "AdmaFine (registered trademark; hereinafter omitted) SC4500-SQ", manufactured by Admatex Co., Ltd.; fused silica, D50 = 1.0 μm ・D2: "AdmaFine SC2500-SQ", manufactured by Admatex Co., Ltd.; fused silica, D50 = 0.5 μm ・D3: "AdmaFine FC920G-SQ", manufactured by Admatex Co., Ltd.; fused silica, D50 = 5.0 μm ・D4: "FB-510FC", manufactured by Denka Co., Ltd.; fused silica, D50 = 12.0 μm ・D5: "AdmaFine AO-502", manufactured by Admatex Co., Ltd.; alumina, D50 = 0.6 μm

[0067] <(E) Low-elasticity agents> ・E1: "SF 8421", manufactured by Dow Toray Corporation; epoxy-polyether modified silicone oil ・E2: "Ricon 657E", manufactured by Clay Valley Corporation; epoxy-modified liquid polybutadiene, liquid rubber ・E3: "Nanostrength M65N", manufactured by Arkema Corporation; block copolymer of polymethyl methacrylate and polybutyl acrylate, thermoplastic elastomer

[0068] <Other ingredients> Epoxysilane coupling agent: "Dynasylan® GLYMO", Evonik Japan Co., Ltd.; 3-Glycidyloxypropyltrimethoxysilane; Aminosilane coupling agent: "SZ-6083", Dow Toray Industries, Inc.; N-Phenyl-3-aminopropyltrimethoxysilane; Coloring agent: "Mitsubishi® Carbon Black MA100", manufactured by Mitsubishi Chemical Corporation

[0069] The particle sizes of the inorganic filler (D10, D50, and D90) were measured using the "Mastersizer® 3000" laser diffraction scattering particle size distribution analyzer (manufactured by Malvern Panalytical).

[0070] [Evaluation] The epoxy resin compositions and sealing resin sheets obtained in each of the above examples and comparative examples were evaluated as follows. The evaluation results are shown in Tables 1 to 4. Note that Comparative Example 5 could not be evaluated because the epoxy resin composition could not be mixed evenly.

[0071] (Gel Time) The gel time of the epoxy resin composition was measured by a method conforming to the gelation time Method A specified in JIS C 2161:2010, 7.5.1. A 1 g sample of the epoxy resin composition was quickly spread in a circle of approximately 50 mm in diameter on a hot plate at 175°C using a stirring rod, and stirred in a circular motion at a speed of drawing a circle approximately once every second. The time until the sample became gel-like and could no longer be stirred was measured. If the gel time is 150 seconds or less, the epoxy resin composition can be said to have an appropriate pot life (working time). If the gel time is 80 seconds or more, the epoxy resin composition can be said to have a sufficient pot life. The gel time may be 82 to 140 seconds, or 85 to 130 seconds.

[0072] (Viscosity) The viscosity of the epoxy resin composition at 120°C was measured using a rotary rheometer ("ARES-G2", manufactured by T.A. Instruments; measurement conditions: 25 mm diameter aluminum parallel plate probe, 1 mm gap, frequency 10 Hz, temperature 120°C). If the viscosity is 40 Pa·s or less, the epoxy resin composition can be said to have sufficient fluidity. The viscosity may be 1 to 30 Pa·s or 3 to 24 Pa·s.

[0073] (Loss coefficient (tanδ)) The loss coefficient (tanδ), which represents the ratio (G'' / G') of the storage shear modulus G' to the loss shear modulus G'' of the epoxy resin composition, was measured using a rotary rheometer ("ARES-G2", manufactured by T.A. Instruments Co., Ltd.; measurement conditions: 25 mm diameter aluminum parallel plate probe, 1 mm gap, frequency 10 Hz, temperature range 20 to 180 °C, heating rate 5 °C / min), and the tanδ at 25 °C was determined. If tanδ is 0.5 or higher, a flexible sealing resin sheet is likely to be obtained. Also, if tanδ is 3.0 or lower, a sealing resin sheet with appropriate tack and good handling properties is likely to be obtained.

[0074] (Tack) The tack of the sealing resin sheet was evaluated by how easily the release film could be peeled off by hand from a 0.5 mm thick sealing resin sheet. A was evaluated when the release films on both sides could be easily peeled off, B was evaluated when the release film on one side was difficult to peel off, and C was evaluated when the sealing resin sheet was damaged when the release film was peeled off.

[0075] (Flexibility) A test specimen (10 mm wide, 50 mm long, 0.5 mm thick) cut from a 0.5 mm thick sealing resin sheet was clamped 15 mm from one end in the longitudinal direction, and set at a height of 18 mm from the top surface of the stand with the main surface of the sample horizontal. The time until one end of the test specimen contacted the top surface of the stand due to its own weight was measured. If the time until contact was less than 600 seconds, the sealing resin sheet had good flexibility and was easy to handle. The time until contact may be less than 300 seconds or less than 120 seconds.

[0076] (Glass transition temperature) The glass transition temperature was measured for a sample cut from a cured product obtained by heating a 0.5 mm thick sealing resin sheet at 175°C for 3 minutes, using a thermomechanical analyzer ("TMA7100", manufactured by Hitachi High-Tech Corporation; temperature range -50 to 300°C, heating rate 10°C / min). (A) When the epoxy resin contains semi-solid or liquid material, the glass transition temperature may be 15 to 60°C, 20 to 55°C, or 30 to 50°C in order to properly seal the semiconductor device. (A) When the epoxy resin contains only solid material, the glass transition temperature may be 100 to 150°C, 110 to 140°C, or 120 to 130°C in order to properly seal the semiconductor device.

[0077] (Module of Elasticity) The modulus of elasticity at 25°C was measured for a sample cut from a cured product obtained by heating a 0.5 mm thick sealing resin sheet at 175°C for 3 minutes, using a dynamic viscoelasticity measuring device ("DMA7100", manufactured by Hitachi High-Tech Corporation; temperature range -50 to 300°C, heating rate 10°C / min). If the modulus of elasticity is 35 GPa or less, the sealing resin sheet is likely to have adequate flexibility. Also, if the modulus of elasticity is 3 GPa or more, a well-sealed semiconductor device is likely to be obtained. The modulus of elasticity may be 5 to 28 GPa or 10 to 25 GPa.

[0078] (Wafer Warpage) A test specimen simulating a sealed semiconductor package was prepared by bonding a 0.5 mm thick sealing resin sheet to a 12-inch diameter silicon wafer (775 μm thick), curing it in an oven at 120°C for 60 minutes, and then post-curing it at 175°C for 8 hours. The test specimen was placed on a horizontal surface, and the displacement of the height position from the horizontal plane of the lower surface of the outer periphery of the specimen, which was warped concavely on the upper surface, was measured as wafer warpage. If the wafer warpage is less than 3.0 mm, it can be said that the semiconductor package has sufficiently small warpage. The wafer warpage may be 2.5 mm or less, or 2.0 mm or less.

[0079] (Substrate warping) Adhesive sheets ("TBS-702", manufactured by Kyocera Corporation; 1 mm x 1 mm, 10 μm thick) were attached to the four corners of a silicon chip (30 mm x 30 mm, 0.3 mm thick). This chip was placed in the center of the surface of an FR-4 substrate (300 mm x 300 mm, 0.5 mm thick) so that the side with the adhesive sheet attached was in contact with the FR-4 substrate. Chips with adhesive sheets attached were placed similarly at a distance of 10 mm from each of the four sides of the chip. This was repeated to place a total of 49 silicon chips on the FR-4 substrate. The FR-4 substrate with the chips placed on it was heated in an oven at 100°C for 60 minutes to cure the adhesive sheets. A test specimen simulating a encapsulated semiconductor package was fabricated by placing an encapsulating resin sheet (290 mm x 290 mm, 0.35 mm thick) on the chip portion of this FR-4 substrate, compression molding (120°C, 5 MPa, 30 minutes), and post-curing by heating at 175°C for 8 hours. The test specimen was placed on a horizontal surface, and the displacement of the height position from the horizontal plane of the lower surface of the central part of the test specimen, which was convexly curved on the upper surface, was measured as the substrate warp. If the substrate warp is less than 3.0 mm, it can be said that the semiconductor package has sufficiently small warp. The substrate warp may be 2.8 mm or less, or 2.5 mm or less.

[0080] (Filling Properties) A ​​resin-encapsulated chip sample 10, mainly for evaluation purposes for 3D mounting, was fabricated as shown in Figure 1. Adhesive sheets 12 ("TBS-702", manufactured by Kyocera Corporation; 1 mm x 1 mm, 10 μm thick) were attached to the four corners of a silicon chip 11 (10 mm x 10 mm, 0.5 mm thick). This chip 1 was placed in the center of a 6-inch diameter silicon wafer 13 so that the adhesive side of the adhesive sheet 12 was in contact with the silicon wafer 13. Chips 11 with adhesive sheets 12 attached were placed similarly at a distance of 5 mm from each of the four sides of the chip 11. The silicon wafer 13 on which the chips 11 were placed was heated in an oven at 100°C for 60 minutes to cure the adhesive sheets 12. A sealing resin sheet 14 (60 mm x 60 mm, 1.0 mm thick) was placed on the chip portion of the silicon wafer 13 (gap G 10 μm below the chip), placed in a vacuum oven at 120°C, left under vacuum for 5 minutes, then released to the atmosphere, and heated at 120°C for 60 minutes to cure the sealing resin sheet 14. After that, the chip 11 was diced with a margin of 1 mm from all four sides and a size of 12 mm x 12 mm to prepare a resin-sealed chip sample 10. The resin-sealed chip sample 10 was observed with an ultrasonic microscope ("Gen6 C-SAM", manufactured by Nordson) to confirm whether or not the gap G was filled with resin (sealant). If the filling was insufficient, it was judged as NG.

[0081] (Reflow Resistance) The resin-encapsulated chip samples 10 prepared in the above evaluation of fillability were left to stand under conditions of humidity sensitivity level (MSL) level 3 (30°C, 60% RH for 168 hours), and then heated in an infrared reflow oven (heating conditions: held at 220°C or higher for 90 seconds, then at a peak temperature of 260°C for 5 seconds or less). After that, the appearance of the resin-encapsulated chip samples 10 was visually inspected. If delamination or cracking occurred, it was judged as NG.

[0082] (Humidity Resistance Reliability) A PBGA (Plastic Ball Grid Array) package sample 20 for evaluation, mainly for 2.5D mounting, was fabricated as shown in Figure 2. A semiconductor element 21 (with zigzag wiring formed on the surface by aluminum deposition, and the peripheral parts other than the electrode pads covered with 10 μm thick polyimide, 10 mm × 10 mm) was placed on a resin substrate 22 (bismaleimide triazine resin, 35 mm × 35 mm) and wire-bonded with copper wire 23 (diameter 20 μm, length 3.5 mm). This was covered with a sealing resin sheet 24 (30 mm × 30 mm, thickness 1.6 mm), compressed and molded (175°C, 6 MPa, 180 seconds), and then heated at 175°C for 4 hours to perform post-curing, thereby fabricating a PBGA package sample 20 (thickness 1.2 mm). PBGA package sample 20 was left to stand at 30°C and 60% RH for 168 hours, and then heated in an infrared reflow oven (heating conditions: held at 220°C or higher for 90 seconds, followed by a peak temperature of 260°C for less than 5 seconds). Subsequently, the PBGA package sample 20 underwent a pressure cooker test (PCT) (121°C, 0.25 MPa, 100% RH, 168 hours). If an open defect occurred, it was judged as NG.

[0083] (High-Temperature Storage Reliability) PBGA package samples 20 were prepared in the same manner as in the evaluation of humidity resistance described above, and then subjected to standing at 30°C and 60% RH, followed by heating in an infrared reflow oven. A highly accelerated lifetime test (HAST) (130°C, 85% RH, 1000 hours) was then performed on these samples. If an open failure occurred, the sample was judged as NG.

[0084]

[0085]

[0086]

[0087]

[0088] As can be seen from the evaluation results shown in Tables 1 to 4, the encapsulating resin sheet of this disclosure has appropriate tackiness, is easy to handle, does not cause warping of the encapsulated semiconductor package (simulated test piece), and has good filling ability for narrow gaps of 10 μm. Furthermore, it was confirmed that resin-encapsulated semiconductor devices manufactured using the encapsulating resin sheet of this disclosure have good reflow resistance, humidity resistance reliability, and high-temperature storage reliability.

[0089] 10 Resin-encapsulated chip sample 11 Chip 12 Adhesive sheet 13 Silicon wafer 14, 24 Encapsulating resin sheet G Gap 20 PBGA package sample 21 Semiconductor device 22 Resin substrate 23 Copper wire

Claims

1. A semiconductor encapsulating resin sheet comprising (A) epoxy resin, (B) phenolic resin curing agent, (C) curing accelerator, and (D) inorganic filler, wherein (D) inorganic filler has a content of 60.0 to 87.0% by mass and a cumulative volume 50% particle size (D50) of 0.3 to 5.0 μm.

2. (D) The semiconductor encapsulating resin sheet according to claim 1, wherein the inorganic filler has a ratio (D90 / D10) of 1.5 to 25.0 between the particle diameter at 90% of the cumulative volume (D90) and the particle diameter at 10% of the cumulative volume (D10).

3. (A) The semiconductor encapsulating resin sheet according to claim 1 or 2, wherein the epoxy resin comprises at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2). (In the formula, n is an integer from 1 to 20, and A is independently of each other, (CH ２ ) ｒ (r is an integer from 1 to 100), B is independently CH ２ or C(CH ３ ) ２ (That is the case.) 4. (A) The semiconductor encapsulating resin sheet according to claim 3, wherein the epoxy resin contains a compound represented by formula (1), and the epoxy equivalent of the compound represented by formula (1) is 200 to 1400 g / eq.

5. (A) The semiconductor encapsulating resin sheet according to claim 3 or 4, wherein the epoxy resin contains a compound represented by formula (1), and the compound represented by formula (1) is semi-solid at 25°C.

6. (A) A semiconductor encapsulating resin sheet according to any one of claims 3 to 5, wherein the epoxy resin comprises a compound represented by formula (2).

7. A semiconductor encapsulating resin sheet according to any one of claims 1 to 6, for use as mold underfill.

8. A resin-encapsulated semiconductor device in which a semiconductor element fixed on a substrate is encapsulated with a cured product of a semiconductor encapsulating resin sheet according to any one of claims 1 to 7.

9. The resin-sealed semiconductor device according to claim 8, wherein the semiconductor element is formed by a through-silicon electrode or a flip-chip junction.

10. A method for manufacturing a resin-encapsulated semiconductor device, comprising the step of encapsulating a semiconductor element by curing a semiconductor encapsulation resin sheet according to any one of claims 1 to 7 by compression molding, lamination molding, or oven molding.

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