Sintering bonding sheet

Abstract

Provided is a sheet for sintering bonding, which is provided with a sintering bonding layer that contains an organic binder and sinterable particles containing a conductive metal, and in which the maximum dimension among observed void dimensions is 100 [mu] m or less in an observation image obtained by observing the surface of the sintering bonding layer at 100 magnification.

Description

[0001] Cross-references to related applications

[0002] This application claims the priority of Japanese Patent Application No. 2023-094868, which is incorporated herein by reference in the description of the present application. Technical Field

[0003] The present invention relates to a sintered bonding sheet used, for example, in manufacturing a semiconductor device. Background Art

[0004] Conventionally, there is known a sintered bonding sheet used in the manufacture of semiconductor devices. Such a sintered bonding sheet has a sintered bonding layer containing an organic binder and sinterable particles containing a conductive metal. The sintered bonding layer has pressure-sensitive adhesive properties due to the organic binder.

[0005] In the manufacture of semiconductor devices, the sintered bonding layer is disposed between one surface of a substrate and a semiconductor element (semiconductor chip, etc.) and sintered to bond the substrate and the semiconductor element via the sintered bonding layer.

[0006] For example, the following steps are performed to manufacture a semiconductor device.

[0007] (1) After a semiconductor wafer is attached to and fixed on the adhesive layer of a dicing tape in which a base material and an adhesive layer are laminated, the semiconductor wafer is diced to separate into a plurality of semiconductor elements.

[0008] (2) After peeling and lifting a semiconductor element from the adhesive layer using a tool such as a clamp, the semiconductor element is pressed onto the sintered bonding layer of the sintered bonding sheet. The pressing force is used to separate a portion of the sintered bonding layer into pieces with a size corresponding to that of the semiconductor element. At the same time, the single-piece sintered bonding layer is bonded to the semiconductor element, and the tool such as a clamp is lifted upward, thereby picking up a single semiconductor element bonded with the sintered bonding layer.

[0009] (3) A single semiconductor element having a sintered bonding layer bonded thereto is bonded to one surface of a substrate (a region for mounting the semiconductor element). That is, the single semiconductor element is temporarily fixed to the substrate.

[0010] (4) The above steps (2) and (3) are repeated multiple times in the same manner, thereby temporarily fixing a plurality of individual semiconductor elements to which the sintered bonding layer is bonded in the semiconductor element mounting region of the substrate. Thus, an intermediate product of a semiconductor device is obtained.

[0011] (5) A sintering treatment is performed by heating the intermediate product of the semiconductor device within a temperature range at which the sinterable particles in the sintering bonding layer can be sintered to each other, thereby sintering the sinterable particles to each other and causing at least a portion of the organic binder to disappear from the sintering bonding layer, thereby bonding a plurality of semiconductor elements to the semiconductor element mounting region in the substrate.

[0012] After the above-mentioned steps, the plurality of semiconductor elements are fixed in the semiconductor element mounting region in the substrate by sintering the sinterable particles contained in the sintered bonding layer. That is, the plurality of semiconductor elements are fixed in the semiconductor element mounting region in the substrate by means of the single piece of the sintered bonding layer after the sintering process.

[0013] It should be noted that in the manufacture of semiconductor devices, as an alternative to implementing the above-mentioned steps (1) and (2), sometimes a sintered bonding layer is overlapped on the adhesive layer of the dicing tape, and then a semiconductor wafer is further adhered to the sintered bonding layer and the semiconductor wafer, and the semiconductor element with the sintered bonding layer adhered to it is picked up.

[0014] As a sintered bonding sheet that can be used in the above-mentioned method of manufacturing a semiconductor device, for example, there is a sheet having a sintered bonding layer that becomes a strong sintered layer after sintering (for example, Patent Document 1).

[0015] Specifically, in the sintered bonding layer of the sintered bonding sheet described in Patent Document 1, the average area of ​​the pores in the cross section after heating under specific heating conditions is 0.005 μm. 2 ~0.5μm 2 It should be noted that the specific heating conditions are conditions in which the temperature is increased from 80°C to 300°C at a heating rate of 1.5°C / sec under a pressure of 10 MPa and then maintained at 300°C for 2.5 minutes.

[0016] Prior art literature

[0017] Patent Literature

[0018] Patent Document 1: Japanese Patent Application Publication No. 2017-066384 Summary of the invention

[0019] Problem that the invention aims to solve

[0020] However, if a single piece of the sintered bonding layer after sintering is used in an environment where the temperature rises and falls repeatedly, the bonding with the adherend such as a substrate or a semiconductor element may become insufficient. In detail, if the single piece of the sintered bonding layer is subjected to multiple temperature rises and falls, it is possible that a portion of the interface between the sintered bonding layer and the adherend may peel off or cracks may occur inside the sintered bonding layer. If the above peeling occurs or the above cracks occur, it may not be possible to fully maintain the bonding between the sintered bonding layer and the adherend, resulting in reduced reliability as a product.

[0021] However, it can be said that sufficient research has not yet been conducted on a sintering bonding sheet that can sufficiently maintain bonding with an adherend even when used in an environment where the temperature repeatedly rises and falls.

[0022] Therefore, an object of the present invention is to provide a sintering bonding sheet which can sufficiently maintain bonding with an adherend even when used in an environment where the temperature repeatedly rises and falls.

[0023] Solutions for solving problems

[0024] In order to solve the above-mentioned problems, the sheet for sintering bonding according to the present invention comprises a sintering bonding layer, wherein the sintering bonding layer comprises an organic binder and sinterable particles containing a conductive metal.

[0025] In an observation image obtained by observing the surface of the sintered bonding layer at 100 times magnification, the largest size of the voids observed was 100 μm or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic cross-sectional view of the sheet for sintering bonding according to the present embodiment cut along the thickness direction.

[0027] Figure 2A It is a schematic cross-sectional view showing a state where a semiconductor chip is lifted up from a dicing tape by a clamper.

[0028] Figure 2B It is a schematic cross-sectional view showing a state when a part of the sintered bonding layer of the sintered bonding sheet is separated into individual pieces.

[0029] Figure 2C It is a schematic cross-sectional view showing a state when a part of the sintered bonding layer of the sintered bonding sheet is separated into individual pieces.

[0030] Figure 2D This is a schematic cross-sectional view showing a state in which one semiconductor chip having a sintered bonding layer attached thereto is temporarily fixed to a substrate.

[0031] Figure 3AIt is a schematic cross-sectional view showing a state where another semiconductor chip is lifted up from the dicing tape by a clamper.

[0032] Figure 3B It is a schematic cross-sectional view showing a state where another semiconductor chip as a single piece to which a sintered bonding layer is attached is temporarily fixed to a substrate.

[0033] Figure 4A This is a schematic cross-sectional view showing an example of a state where a single piece of a sintered bonding layer is heated while being pressed.

[0034] Figure 4B This is a schematic cross-sectional view showing an example of a case where a single piece of a sintered bonding layer is heated without being pressed.

[0035] Figure 5A These are photographs showing some examples of observed images obtained by observing the surface of the sintered bonding layer.

[0036] Figure 5B These are photographs showing some examples of observed images obtained by observing the surface of the sintered bonding layer.

[0037] Figure 5C These are photographs showing some examples of observed images obtained by observing the surface of the sintered bonding layer.

[0038] Description of Reference Numerals

[0039] 10: Sintering bonding sheet,

[0040] 1: Support layer, 2: Sintered bonding layer,

[0041] A: Clamp, B: Semiconductor chip, C: Dicing tape,

[0042] D: ceramic insulating layer, E: copper chip pad, F: copper thin layer, G: first base, H: second base. DETAILED DESCRIPTION

[0043] Hereinafter, one embodiment of the sinter bonding sheet according to the present invention will be described with reference to the drawings.

[0044] The sintered bonding sheet 10 according to this embodiment is as follows. Figure 1 As shown in FIG. 1 , the support layer 1 includes a sintered bonding layer 2 including an organic binder and sinterable particles containing a conductive metal. The sintered bonding layer 2 is overlapped on one surface of the support layer 1 .

[0045] [Sintered Bonding Layer of Sintered Bonding Sheet]

[0046] The sintered bonding sheet 10 of the present embodiment is, for example, in the form of a long strip. The sintered bonding sheet 10 of the present embodiment can be stored in a state of being wound into a cylindrical shape.

[0047] The sintered bonding layer 2 contains an organic binder and has pressure-sensitive adhesiveness. Therefore, the sintered bonding layer 2 can be temporarily bonded to an adherend by receiving a pressing force.

[0048] In addition, if the sintering treatment is applied to the sintered bonding layer 2, the sinterable particles inside are sintered to each other. The sintered bonding layer 2 after the sintering treatment is, for example, arranged between the substrate and the semiconductor chip B to bond the two. In the sintered bonding layer 2 after the sintering treatment, at least a portion of the organic binder has disappeared. In the sintered bonding layer 2, the organic binder preferably has almost no residue, and more preferably has no residue at all.

[0049] In the observation image obtained by observing the surface of the sintered bonding layer 2 at 100 times magnification, the maximum size of the observed voids is 100 μm or less. It should be noted that the description "the maximum size is 100 μm or less" also includes the case where no voids are observed at all.

[0050] Since the sintered bonding layer 2 has the above-described configuration, even when the sintered bonding layer 2 is used in an environment where the temperature repeatedly rises and falls, the bonding between the sintered bonding layer 2 and the adherend can be sufficiently maintained.

[0051] The maximum size is preferably 95 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. In the observed image, it is most preferred that no voids are observed at all. When voids are observed, the maximum size of the voids may be 5 μm or more.

[0052] In this embodiment, it is preferred that: at least 9 mm of the observed image 2 In the range of , the area ratio of the voids is 5.0% or less.

[0053] In the sintered bonding layer 2, by setting the area ratio of the voids to 5.0% or less as described above, the bonding between the sintered bonding layer 2 and the adherend can be more fully maintained even when the sintered bonding layer 2 is used in an environment where the temperature repeatedly rises and falls.

[0054] The area ratio of the voids is preferably 2.0% or less, more preferably 1.0% or less, further preferably 0.5% or less, and most preferably 0%. It should be noted that the area ratio of the voids may be 0% or more.

[0055] The maximum size of the voids can be reduced by, for example, further reducing the solid content concentration in a varnish (described later) containing sinterable particles, an organic binder, and an organic solvent when preparing the sintered bonding layer 2. The maximum size can also be reduced by further reducing the viscosity of the varnish.

[0056] Likewise, the area ratio of the voids can be reduced by further reducing the solid content concentration in the varnish (described later in detail) or further reducing the viscosity of the varnish.

[0057] [Method of observing the surface of sintered bonding layer]

[0058] The surface of the sintered bonding layer 2 was observed as follows: Then, the maximum size of the voids and the area ratio of the voids were determined by performing image analysis on the observed image.

[0059] Use an optical microscope to observe the surface of the sintered bonding layer at a magnification of 100 times. As the observation site, select the central part of a single surface of the sintered bonding layer (the surface that does not overlap with the supporting layer 1). As an optical microscope, for example, a digital microscope is used. In more detail, the sintered bonding layer is placed on a transparent glass and photographed while being illuminated from above and below. As specific conditions for lighting and focusing during photography, for example, the conditions described in the image analysis item in the later-described embodiments can be used.

[0060] [Image analysis method for observation images]

[0061] For each image captured as described above, the image analysis is performed as follows. Specifically, first, the region with a chroma of 0 or more and 50 or less is extracted in such a way that the gap portion of the image and the portion other than the gap are clearly distinguished from each other. Preferably, the lighting conditions and the focus conditions are adjusted in such a way that the boundary line defined by the chroma of 50 is along the outline (outer edge) of the gap. For example, by using such conditions to perform binarization processing, the portion other than the gap becomes a white portion, and the gap portion becomes a colored portion.

[0062] Next, the maximum size of the spaces extracted in each image is obtained. Since the shapes of spaces vary, the distance between the two points in each space that are farthest from each other is taken as the size of each space.

[0063] In addition, at least 9mm of the observed image 2 Specifically, the area of ​​the black gap is calculated to be at least 9 mm. 2 The proportion of the observation image. At least 9mm 2 The shape of the observed image is preferably square. The area of ​​the observed image should be at least 9 mm 2 That is, preferably 9mm 2 Above and 11mm 2 It should be noted that the area ratios described above are calculated in at least five randomly selected observation images, and the values ​​are arithmetic averaged to finally determine the area ratio of the voids.

[0064] The above-mentioned image analysis can be performed using software attached to a device such as a digital microscope.

[0065] The conductive metal contained in the sinterable particles has an electrical conductivity of 100 [μS / cm] or more (10 6 [S / m] or more).

[0066] Examples of the conductive metal include gold, silver, copper, palladium, tin, and nickel. The conductive metal may be an alloy of two or more metals selected from the group consisting of gold, silver, copper, palladium, tin, and nickel.

[0067] The sinterable particles may contain metal oxides such as silver oxide, copper oxide, palladium oxide, and tin oxide.

[0068] In this embodiment, the sinterable particles preferably contain at least one selected from the group consisting of silver, copper, silver oxide and copper oxide. As described below, the bonding property when the semiconductor element is bonded to the substrate via the individual sintered bonding layer 2 (sintered bonding layer individual pieces 2') is improved.

[0069] The sinterable particles preferably contain at least one of silver and copper as the conductive metal. This further improves the thermal conductivity and electrical conductivity of the sintered bonding layer 2 .

[0070] From the viewpoint of oxidation resistance, the sinterable particles preferably contain silver as the conductive metal. When the sinterable particles contain silver, the sintering process can be suitably performed even in an air atmosphere. Specifically, for example, the sintering process when the semiconductor element such as the semiconductor chip B is bonded to the substrate can be suitably performed in an air atmosphere. On the other hand, when the sinterable particles contain, for example, copper, it is desirable to perform the sintering process in an inactive environment such as a nitrogen atmosphere in order to prevent oxidation of the copper.

[0071] The sinterable particles may contain a metal oxide. For example, the sinterable particles may be in a state where the surface layer of the metal particles is partially converted into a metal oxide.

[0072] For example, the sinterable particles may have a core-shell structure having a core portion and a shell portion covering the core portion. The core portion may contain at least one of silver and copper as a main component. The shell portion may contain gold, silver, silver oxide, or copper oxide as a main component. For example, the sinterable particles may be in a state where at least a portion of the surface of the silver particles is covered with silver oxide, or may be in a state where at least a portion of the surface of the copper particles is covered with copper oxide.

[0073] More specifically, the particles formed of multiple metals may be particles having a core portion formed of nickel, copper, silver, or aluminum, and a shell portion covering at least a portion of the surface of the core portion and formed of gold, silver, or copper, for example.

[0074] In addition, as sinterable particles, composite particles containing metals and materials other than metals can be cited. As composite particles, for example, particles having a core formed of resin particles and a surface layer covering at least a portion of the surface of the core and formed of a metal such as nickel or gold can be cited. The core can be formed of a carbon material such as carbon black and carbon nanotubes. It should be noted that as composite particles, particles obtained by surface-treating metal particles with fatty acids can be used.

[0075] When the sinterable particles contain silver, more specifically, when the sinterable particles are silver particles, the silver particles may contain silver elements and other elements (metal elements, etc.) as unavoidable impurity elements. Alternatively, the silver particles may be subjected to surface treatment (e.g., silane coupling treatment). Examples of the surface treatment agent for the silver particles include fatty acid-based covering agents, amine-based covering agents, and epoxy-based covering agents.

[0076] As silver particles, silver particles surface-treated with a coating agent (hereinafter sometimes referred to as coating agent-treated silver particles) are preferred from the following viewpoints. By using coating agent-treated silver particles as sinterable particles, the affinity between the organic binder and the sinterable particles can be further improved in the sintered bonding layer 2 before the sintering treatment. As a result, the sinterable particles can be more fully dispersed in the sintered bonding layer 2 before the sintering treatment.

[0077] In manufacturing the semiconductor device, as described later, by subjecting the sintered bonding layer 2 to a sintering treatment at a temperature equal to or higher than a predetermined temperature, at least a portion of the organic binder disappears from the sintered bonding layer 2 .

[0078] In addition, as the above-mentioned sinterable particles, only one kind may be used, or two or more kinds may be used in combination.

[0079] The shape of the sinterable particles is, for example, needle-like, filament-like, spherical, or plate-like (including scaly) shapes. Among these shapes, a spherical shape is preferred.

[0080] By making the sinterable particles spherical, the sinterable particles can be dispersed more favorably in a varnish for obtaining a sintered bonding layer 2 described later.

[0081] The sinterable particles are sintered to each other by a sintering process heated to a predetermined temperature. The sinterable particles are particles in which at least a portion of each particle is formed of the conductive metal and fixed to each other when heated at a predetermined temperature. Therefore, a path for conducting heat to the inside of the sintered bonding layer 2 is formed by the sintering process. In particular, a heat conduction path in the thickness direction is formed. As a result, the thermal conductivity (heat dissipation) of the sintered bonding layer 2 can be increased.

[0082] The sinterable particles can be sintered at a heating temperature of 400° C. or lower. In other words, sinterable particles in which necking is observed on the outer surface when heated at a temperature of 400° C. or lower can be used.

[0083] The temperature at which the sinterable particles are sintered can be measured using a thermogravimetric differential thermal analyzer.

[0084] Specifically, a thermogravimetric differential thermal analyzer (e.g., a differential thermal balance TG8120 manufactured by Rigaku Corporation) is used to perform the measurement under the following conditions. The Tg curve and the DTA curve are obtained by the measurement. The temperature of the peak of the maximum DTA curve confirmed near the time of the drop of the Tg curve is set as the sintering temperature of the sinterable particles.

[0085] <Measurement Conditions>

[0086] Heating rate: 10℃ / min

[0087] ·Measurement atmosphere: Air

[0088] ·Measurement temperature range: room temperature (23±2℃)~500℃

[0089] It should be noted that, as the conductive metal, sinterable particles including gold, silver, copper, palladium, tin, nickel, and alloys thereof can be sintered at a heating temperature of 400° C. or lower.

[0090] The average particle size of the sinterable particles is preferably 1 nm or more, more preferably 10 nm or more, and further preferably 50 nm or more. Thus, the dispersibility of the sinterable particles becomes better in the varnish used to obtain the sintered bonding layer 2 described later. Therefore, the sintered bonding layer 2 in which the sinterable particles are fully dispersed can be produced from the varnish.

[0091] On the other hand, the average particle size of the sinterable particles is preferably 10000 nm or less, more preferably 3000 nm or less, further preferably 1000 nm or less, and further preferably 500 nm or less. Thus, the sintered bonding layer 2 can have a smoother surface.

[0092] The average particle size of the sinterable particles can be determined by observing the cross section of the sintered bonding layer 2 using a scanning electron microscope (SEM). Specifically, the average particle size can be determined by the following procedure. The following procedure is performed on the sintered bonding layer 2 before a sintering process (described later) is performed.

[0093] (1) As a measurement sample, a sintered bonding layer 2 having a size of 10 mm×10 mm and a thickness of 50 μm (0.05 mm) when viewed in a direction perpendicular to the thickness direction was prepared.

[0094] (2) The measurement sample is cut and the exposed cross section is subjected to a full surface treatment, and then subjected to a conductive treatment to prepare a sample for SEM observation.

[0095] (3) A SEM observation image is acquired at an accelerating voltage of 3 kV (at a magnification of 10,000 or 100,000 times depending on the size of each particle).

[0096] (4) Perform image analysis on the SEM observation image to identify each particle. Particles at the ends of the observation image are excluded. Calculate the equivalent circle diameter of each identified particle. The equivalent circle diameter refers to the diameter of a perfect circle calculated from the area of ​​each particle, assuming that each particle is a perfect circle.

[0097] The sintered bonding layer 2 preferably contains 60% by mass or more of sinterable particles, more preferably 65% ​​by mass or more, further preferably 70% by mass or more, and most preferably 80% by mass or more. The sintered bonding layer 2 preferably contains 99% by mass or less of sinterable particles, more preferably 98% by mass or less, and further preferably 97% by mass or less.

[0098] By setting the content of the sinterable particles within the above range, the sinterable particles are sintered together by the sintering process, and when a semiconductor element such as the semiconductor chip B is bonded to a substrate, the bonding by the sintered bonding layer 2 after the sintering process can exhibit sufficient reliability.

[0099] The content of sinterable particles in the sintered bonding layer 2 can be calculated based on the measured value of the ash content remaining after burning the sintered bonding layer 2. For example, a thermogravimetric analyzer (e.g., TG209F1) can be used and the measurement can be performed according to the following steps. It should be noted that the measurement using the thermogravimetric analyzer is preferably performed under a nitrogen gas flow.

[0100] (1) A measurement sample of the sintered bonding layer 2 weighing about 50 mg is heated from room temperature (23±2° C.) to 650° C.

[0101] (2) The organic binder in the measurement sample is thermally decomposed by maintaining the sample at a temperature of 650° C. for 30 minutes.

[0102] (3) Calculate the ratio of the mass of the residual component (ash) to the weighed value of the measurement sample (about 50 mg).

[0103] In the present embodiment, the sintered bonding layer 2 preferably contains, as organic binders, a first organic binder and a second organic binder having a molecular weight smaller than that of the first organic binder.

[0104] The first organic binder is preferably a thermally decomposable polymer binder. The thermally decomposable polymer binder is a binder that undergoes thermal decomposition by sintering. The thermally decomposable polymer binder has the function of keeping the sintered bonding layer 2 in a sheet shape until before the sintering. From the viewpoint of more fully exerting this function, the thermally decomposable polymer binder is preferably in a solid state at room temperature (23±2°C).

[0105] Examples of the thermally decomposable polymer binder include polycarbonate resins and acrylic resins. The sintered bonding layer 2 preferably includes at least one of polycarbonate resins and acrylic resins as the first organic binder. The sintered bonding layer 2 may include only polycarbonate resins as the first organic binder.

[0106] Examples of the polycarbonate resin include aliphatic polycarbonates having only aliphatic chains without an aromatic structure such as a benzene ring between carbonates (-OCOO-) in the main chain, and aromatic polycarbonates having an aromatic structure between carbonates (-OCOO-) in the main chain.

[0107] Examples of the aliphatic polycarbonate include polyethylene carbonate and polypropylene carbonate.

[0108] Examples of the aromatic polycarbonate include polycarbonates containing a bisphenol A structure in the main chain.

[0109] Examples of the acrylic resin include polymers of (meth)acrylic acid alkyl esters having a linear or branched alkyl moiety with carbon atoms of 4 to 18. The term "(meth)acrylic" includes both "acrylic" and "methacrylic".

[0110] Examples of the alkyl group (alkyl moiety) of the (meth)acrylate include methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, octyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl and octadecyl.

[0111] The acrylic resin may have a polymerized unit derived from other monomers in addition to the above-mentioned (meth)acrylate in the molecule. Examples of other monomers include carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, sulfonic acid group-containing monomers, and phosphoric acid group-containing monomers.

[0112] Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

[0113] Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride.

[0114] Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and 4-(hydroxymethyl)cyclohexylmethyl (meth)acrylate.

[0115] Examples of the sulfonic acid group-containing monomer include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl(meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

[0116] As a phosphoric acid group-containing monomer, 2-hydroxyethyl acryloyl phosphate etc. are mentioned, for example.

[0117] The second organic binder included in the sintered bonding layer 2 is preferably a volatile binder. The volatile binder is a binder component that completes weight loss (completely desorbs to 0% weight) at a lower temperature than a thermally decomposable polymer binder when measured by thermogravimetric analysis (TGA).

[0118] In this embodiment, the volatile binder preferably exhibits a 1×10 5 The viscosity is a liquid with a viscosity of less than Pa·s. The viscosity is measured using a dynamic viscoelasticity measuring device (machine name "HAAKE MARS III", manufactured by Thermo Fisher Scientific). Specifically, as a tool, parallel plates with a diameter of 20 mm are used, the gap between the plates is set to 100 μm, and the shear rate in the rotational shear is set to 1 s -1 , measure the viscosity.

[0119] Examples of the volatile binder include terpene alcohols, alcohols other than terpene alcohols, alkylene glycol alkyl ethers, and ethers other than alkylene glycol alkyl ethers.

[0120] Examples of the terpene alcohols include isobornylcyclohexanol, citronellol, geraniol, nerol, carveol, and α-terpineol.

[0121] Examples of alcohols other than terpene alcohols include pentanol, hexanol, heptanol, octanol, 1-decanol, ethylene glycol, diethylene glycol, propylene glycol, butanediol, and 2,4-diethyl-1,5-pentanediol.

[0122] Examples of the alkylene glycol alkyl ethers include ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol isobutyl ether, diethylene glycol hexyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol propyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl methyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, and tripropylene glycol dimethyl ether.

[0123] Examples of ethers other than alkylene glycol alkyl ethers include ethylene glycol ethyl ether acetate, ethylene glycol butyl ethyl acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ethyl acetate, and dipropylene glycol methyl ether acetate.

[0124] As the volatile binder, one type may be used alone or two or more types may be used in combination.

[0125] As the volatile binder, from the viewpoint of stability at room temperature, terpene alcohols are preferred, and among the terpene alcohols, isobornylcyclohexanol is more preferred.

[0126] Isobornylcyclohexanol is also called 4-[1,7,7-trimethylbicyclo[2.2.1]heptane-2-yl]cyclohexanol. The boiling point of isobornylcyclohexanol is in the range of 308° C. to 318° C. The vapor pressure of isobornylcyclohexanol at 25° C. is 0.00003 mmHg.

[0127] Isobornyl cyclohexanol has the following characteristic properties. Specifically, isobornyl cyclohexanol has the following properties: when the temperature is raised from room temperature (23±2°C) to 600°C at a temperature increase of 10°C / min under a nitrogen gas flow of 200 mL / min, the mass decreases significantly from above 100°C, and evaporates and disappears at 245°C (no mass reduction above this level is observed). In addition, it has the following properties: it exhibits an extremely high viscosity of up to 1000000 mPa·s at 25°C, but exhibits a relatively low viscosity of less than 1000 mPa·s at 60°C. It should be noted that the mass reduction is the value when the mass reduction rate at the measurement start temperature (room temperature) is set to 0%.

[0128] As described above, isobornyl cyclohexanol shows extremely high viscosity at 25°C, so the sintered bonding layer 2 easily maintains a sheet shape at room temperature. On the other hand, isobornyl cyclohexanol shows a relatively low viscosity at 60°C, as described above, and has adhesiveness. That is, the sintered bonding layer 2 containing isobornyl cyclohexanol can fully maintain a sheet shape at room temperature and can have adhesiveness at a temperature of 60°C or higher.

[0129] The temperature when the semiconductor element is temporarily fixed to an adherend such as a substrate via the sintered bonding layer 2 is generally 60 to 80° C. At such a temperature, isobornylcyclohexanol has adhesiveness for the reasons described above.

[0130] Therefore, the sintered bonding layer 2 contains isobornyl cyclohexanol as the second organic binder, thereby improving the temporary fixation to the adherend such as the substrate. In other words, after the semiconductor element is temporarily fixed to the adherend, the mounting position of the semiconductor element can be further suppressed from being offset or the sintered bonding layer 2 can be further suppressed from floating from the adherend.

[0131] The sintered bonding layer 2 may contain 1 mass % or more of the organic binder, 2 mass % or more, or 3 mass % or more. The sintered bonding layer 2 preferably contains 3 mass % or more of the organic binder, and more preferably contains 5 mass % or more.

[0132] The sintered bonding layer 2 may contain 40 mass % or less of the organic binder, 35 mass % or less, or 30 mass % or less. The sintered bonding layer 2 preferably contains 20 mass % or less of the organic binder, and more preferably contains 10 mass % or less.

[0133] When the sintered bonding layer 2 includes the first organic binder and the second organic binder as organic binders, the proportion (%) of the first organic binder in the total amount of the first organic binder and the second organic binder is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. In the sintered bonding layer 2, the content of the second organic binder is greater than the content of the first organic binder. The proportion (%) of the first organic binder in the total amount of the first organic binder and the second organic binder is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less.

[0134] The sintered bonding layer 2 preferably contains 0.01 mass % or more of the first organic binder, more preferably 0.05 mass % or more, further preferably 0.10 mass % or more, and further preferably 0.20 mass % or more.

[0135] The sintered bonding layer 2 preferably contains 20.0 mass % or less of the first organic binder, more preferably 10.0 mass % or less, further preferably 7.5 mass % or less, and further preferably 5.0 mass % or less.

[0136] The sintered bonding layer 2 preferably contains 0.5 mass % or more of the second organic binder, more preferably 1.0 mass % or more, further preferably 1.5 mass % or more, and further preferably 2.0 mass % or more.

[0137] The sintered bonding layer 2 preferably contains 20.0 mass % or less of the second organic binder, more preferably 15.0 mass % or less, and further preferably 10.0 mass % or less.

[0138] like Figure 1 As shown, the sintered bonding layer 2 may be a single-layer structure. On the other hand, the sintered bonding layer 2 may be a multilayer structure in which a plurality of layers are stacked. When the sintered bonding layer 2 has a multilayer structure, in at least one layer constituting the sintered bonding layer 2, as described above, the maximum size of the voids may be 100 μm or less.

[0139] The complex viscosity of the sintered bonding layer 2 at 25° C. is, for example, 3.0×10 5 [Pa·s] or more and 3.0×10 11 The complex viscosity of the sintered bonding layer 2 at 25°C is preferably 3.0×10 6 [Pa·s] or more, more preferably 3.0×10 7 [Pa·s] or more, more preferably 7.0×10 7 The complex viscosity of the sintered bonding layer 2 at 25°C is preferably 3.0×10 10 [Pa·s] or less, more preferably 3.0×10 9 [Pa·s] or less, more preferably 7.0×10 8 [Pa·s] or less.

[0140] The complex viscosity of the sintered bonding layer 2 at 93° C. is, for example, 3.0×10 4 [Pa·s] or more and 3.0×10 10 The complex viscosity of the sintered bonding layer 2 at 93°C is preferably 3.0×10 5 [Pa·s] or more, more preferably 3.0×10 6 [Pa·s] or more, more preferably 7.0×10 6 The complex viscosity of the sintered bonding layer 2 at 93°C is preferably 3.0×10 9[Pa·s] or less, more preferably 3.0×10 8 [Pa·s] or less, more preferably 7.0×10 7 [Pa·s] or less.

[0141] By making the complex viscosity of the sintered bonding layer 2 within the above range, voids that may exist in the sintered bonding layer 2 before the sintering process (described later) are easily reduced during the sintering process. Therefore, even if the sintered bonding layer 2 after the sintering process is repeatedly subjected to temperature rise and fall during use, it is possible to further suppress the peeling of a part of the interface between the sintered bonding layer 2 and the adherend, and it is possible to further suppress the generation of cracks inside the sintered bonding layer 2. Therefore, even if the sintered bonding layer 2 is repeatedly subjected to temperature rise and fall during use, it is possible to more fully maintain the bonding between the sintered bonding layer 2 and the adherend.

[0142] The complex viscosity of the sintered bonding layer 2 was measured under the following measurement conditions.

[0143] Test piece cut out from the sintered bonding layer: 30 mm long, 5 mm wide

[0144] Measuring device: Dynamic viscoelasticity measuring device

[0145] (Product name: "RSA-G2" (manufactured by IA Instruments, etc.)

[0146] Measurement mode: Stretch mode

[0147] Initial distance between chucks: 20mm

[0148] Stretching speed: 1mm / sec

[0149] Measurement temperature: from 10°C to 100°C (heating rate: 5°C / min)

[0150] At least the value [Pa·s] of the complex viscosity (complex viscosity ratio η*) at 25°C is read.

[0151] It should be noted that, when the test piece was fixed to the chuck tool, two silicone release-treated PET pads (50 μm thick) were used as cushioning materials in the chuck portion to prevent the test piece from breaking. The test piece was clamped by these PET pads.

[0152] The complex viscosity can be reduced by, for example, increasing the amount of the organic binder contained in the sintered bonding layer 2. On the other hand, by reducing the amount of the organic binder contained in the sintered bonding layer 2, the complex viscosity can be increased.

[0153] In this embodiment, the thickness of the sintered bonding layer 2 is preferably 5 μm or more, more preferably 10 μm or more. Alternatively, the thickness of the sintered bonding layer 2 may be 300 μm or less, 200 μm or less, or 100 μm or less.

[0154] Generally speaking, the thinner the thickness of the sintered bonding layer 2 is, the easier it is for the above-mentioned cracks to be generated inside the sintered bonding layer 2 when the temperature rises and falls repeatedly during use. In contrast, in the present embodiment, as described above, in the sintered bonding layer 2, the maximum size of the above-mentioned voids is less than 100 μm. Therefore, even if the sintered bonding layer 2 with a thinner thickness is repeatedly subjected to temperature rises and falls during use, cracks can be suppressed from being generated inside the sintered bonding layer 2. In addition, it is possible to suppress the peeling of a part of the interface between the sintered bonding layer 2 and the adherend due to the above-mentioned voids, etc. Therefore, the bonding between the sintered bonding layer 2 and the adherend can be fully maintained.

[0155] The thickness of the sintered bonding layer 2 is calculated by, for example, measuring the thickness of five randomly selected locations using a digital micrometer (manufactured by PEACOCK, model: R-205), and taking the arithmetic average of these measured values.

[0156] [Supporting layer of sintered bonding sheet]

[0157] In the present embodiment, the support layer 1 of the sintered-bonding sheet 10 functions as a support body in the sintered-bonding sheet 10. The support layer 1 is made of, for example, a plastic film.

[0158] Examples of the material of the plastic film include polyolefin resins, polyester resins, polyurethane resins, polycarbonate resins, polyetheretherketone resins, polyimide resins, polyetherimide resins, polyamide resins, wholly aromatic polyamide resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyphenylene sulfide resins, aromatic polyamide resins, fluororesins, cellulose resins, and silicone resins.

[0159] It should be noted that the supporting layer 1 may be formed of one material or may be formed of two or more materials.

[0160] Examples of the polyolefin resin include low-density polyethylene resin, linear low-density polyethylene resin, medium-density polyethylene resin, high-density polyethylene resin, ultra-low-density polyethylene resin, random copolymer polypropylene resin, block copolymer polypropylene resin, homopolymer polypropylene resin, polybutene resin, polymethylpentene resin, ethylene-vinyl acetate copolymer resin, ionomer resin, ethylene-butene copolymer resin, and ethylene-hexene copolymer resin.

[0161] Examples of the polyester resin include polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene terephthalate resin.

[0162] The supporting layer 1 may have a single-layer structure or a multi-layer structure. It should be noted that a single-layer structure refers to a structure formed of one material. For example, a supporting layer 1 having two or more layers formed of one material stacked on top of each other has a single-layer structure. On the other hand, a supporting layer 1 having two or more layers formed of different materials stacked on top of each other has a multi-layer structure.

[0163] When the support layer 1 is a plastic film, the support layer 1 may be a non-stretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film.

[0164] In addition, the support layer 1 may be a release liner having a release treatment applied to the surface in contact with the sintered bonding layer 2. For example, a release agent may be applied to one surface of the support layer 1 in contact with the sintered bonding layer 2. In this case, when manufacturing a semiconductor device, the single-piece sintered bonding layer 2 (single piece 2' of the sintered bonding layer) can be easily peeled off from one surface of the support layer 1 (release liner).

[0165] The thickness of the supporting layer 1 is preferably 10 μm or more, more preferably 20 μm or more, and further preferably 30 μm or more. The thickness of the supporting layer 1 is preferably 5000 μm or less, more preferably 4000 μm or less, and further preferably 3000 μm or less.

[0166] The thickness of the supporting layer 1 is measured in the same manner as the thickness of the sintered bonding layer 2 described above.

[0167] Next, a method for producing the sintered bonding sheet will be described.

[0168] The method for manufacturing the sintered bonding sheet comprises the following steps:

[0169] A process for preparing a varnish comprising sinterable particles containing a conductive metal, an organic binder and an organic solvent; and

[0170] A step of volatilizing the organic solvent from the varnish to form a sintered bonding layer.

[0171] In the step of preparing the varnish, for example, the sinterable particles, the organic binder, and an organic solvent are mixed to disperse the sinterable particles in the organic solvent and dissolve the organic binder in the organic solvent, thereby preparing the varnish.

[0172] As the organic solvent, for example, alcohols such as ethanol, ketones such as methyl ethyl ketone (MEK), etc. can be used.

[0173] The mixing temperature when preparing the varnish is not particularly limited, and is, for example, 5° C. or higher and 70° C. or lower. The mixing method is not particularly limited, and a mixing method using a general stirring device can be employed.

[0174] The solid content concentration in the varnish is preferably 60% by mass or less, more preferably 58% by mass or less, and further preferably 55% by mass or less. It should be noted that the solid content is components other than the organic solvent, for example, the total amount of the sinterable particles and the organic binder.

[0175] By making the solid content concentration in the varnish lower, the size of the voids that may be formed when the organic solvent evaporates from the varnish (described later) when manufacturing the sintered bonding layer 2 is easily smaller. As a result, the size of the voids after the sintering process also becomes smaller. Therefore, even if the sintered bonding layer 2 is repeatedly subjected to temperature increases and decreases during use, it will further suppress the peeling of a part of the interface between the sintered bonding layer 2 and the adherend due to the above-mentioned voids. In addition, it is possible to further suppress the generation of cracks in the interior of the sintered bonding layer 2 due to the above-mentioned voids. Therefore, the bonding between the sintered bonding layer 2 and the adherend can be more fully maintained.

[0176] It should be noted that the solid content concentration in the varnish may be 30% by mass or more, 40% by mass or more, 50% by mass or more, or 52% by mass or more.

[0177] The viscosity of the varnish at 23°C is preferably 1.0 [Pa·s] or more and 7.0 [Pa·s] or less, and more preferably 2.0 [Pa·s] or more and 5.0 [Pa·s] or less. The viscosity is measured using an E-type viscometer (e.g., machine name "RE-85 type", manufactured by Toki Sangyo Co., Ltd.). Specifically, as a tool, a "1°34'×R24" conical rotor is used, and the viscosity is measured under the conditions of a measurement sample amount of 1.1 mL and a rotation speed of 1.0 rpm.

[0178] Since the viscosity of the varnish is lower, the size of the voids that may be formed when the organic solvent volatilizes from the varnish (described later) when manufacturing the sintered bonding layer 2 is easily smaller. As a result, the size of the voids after the sintering process also becomes smaller. Therefore, even if the sintered bonding layer 2 is repeatedly subjected to temperature rise and fall during use, it will further suppress the peeling of a part of the interface between the sintered bonding layer 2 and the adherend due to the above-mentioned voids. In addition, the generation of cracks in the interior of the sintered bonding layer 2 due to the above-mentioned voids is further suppressed. Therefore, the bonding between the sintered bonding layer 2 and the adherend can be more fully maintained.

[0179] In the process of producing the sintered bonding layer, for example, varnish is applied to a predetermined thickness on the support layer 1 to form a coating film. Next, the coating film is heated to volatilize the organic solvent.

[0180] The sintered bonding sheet 10 manufactured as described above can be used as an auxiliary member in manufacturing a semiconductor device, for example.

[0181] [Method of using the sintered bonding sheet (method of manufacturing a semiconductor device)]

[0182] Next, an example of a method for manufacturing a semiconductor device using the sheet 10 for sintered bonding according to the present embodiment will be described with reference to the drawings.

[0183] The manufacturing method of the semiconductor device described in this embodiment is implemented using, for example, multiple semiconductor chips B, a substrate, the above-mentioned sintering bonding sheet 10 and a pressing member, wherein the substrate has multiple mounting areas for mounting the multiple semiconductor chips B, and the pressing member is used to temporarily fix the multiple semiconductor chips B in the multiple mounting areas respectively.

[0184] Hereinafter, the case where a semiconductor chip B is mounted on a substrate such as a DBC (Direct Bonded Copper) substrate or an AMB (Active Matal Brazing) substrate using a clamp A as a pressing member will be described as an example. These substrates have a copper die pad E and a copper thin layer F on both sides of a ceramic insulating layer D, for example. The copper die pad E is a mounting area for the semiconductor chip B.

[0185] First, a semiconductor wafer is cut on a dicing tape C to obtain a plurality of semiconductor chips B (see Figure 2A ). In other words, the semiconductor wafer is divided into a plurality of pieces to obtain semiconductor chips B. As the dicing tape C, a commercially available product can be used.

[0186] The obtained semiconductor chip B is, for example, in the shape of a rectangular thin plate. The thickness of the semiconductor chip B is, for example, 10 μm or more and 500 μm or less. The thickness of the semiconductor chip B is preferably 20 μm or more and 400 μm or less.

[0187] The area of ​​the semiconductor chip B when viewed from one side in the thickness direction is, for example, 0.01 mm 2 Above and 1000mm 2 The area is preferably 0.04 mm 2 Above and 500mm 2 the following.

[0188] Then, if Figure 2B As shown, the sheet 10 for sintered bonding is placed on the first base G so that the sintered bonding layer 2 is located above the support layer 1 .

[0189] Furthermore, by pressing one semiconductor chip B against the sintered bonding layer 2 with the clamp A, the semiconductor chip B is attached to a portion of the sintered bonding layer 2. The pressure during pressing is preferably 0.01 MPa to 10 MPa, more preferably 0.1 MPa to 5 MPa. In addition, the temperature of the clamp A or the first base G during pressing is preferably 40°C to 150°C, more preferably 50°C to 130°C.

[0190] It should be noted that the shape and size of the surface of the clamper A that contacts the semiconductor chip B are substantially the same as the shape and size of one semiconductor chip B.

[0191] Then, if Figure 2C As shown in the figure, the clamp A is lifted upward. At this time, a part of the sintered bonding layer 2 attached to the semiconductor chip B is lifted upward together with the semiconductor chip B. In other words, in the state of the single piece 2' to which the sintered bonding layer is attached, the semiconductor chip B is lifted upward by the clamp A. Thus, the semiconductor chip B to which the single-piece sintered bonding layer 2 (hereinafter also referred to as the single piece 2' of the sintered bonding layer) is attached is obtained.

[0192] It should be noted that by setting the pressure when pressing the semiconductor chip B against the sintered bonding layer 2 within the above range, or by setting the temperature of the holder A or the first base G within the above range, the semiconductor chip B as a single piece 2' with a sintered bonding layer attached can be suitably obtained.

[0193] Next, the substrate (ceramic insulating layer D, copper die pad E and copper thin layer F) is placed on the second base H (see Figure 2D ).

[0194] And, if Figure 2D As shown in the figure, at any temperature within the range of 25°C to 150°C, the clamp A is lowered in the vertical direction while being held, so that the single piece 2' of the sintered bonding layer attached to the semiconductor chip B is brought into contact with the copper die pad E. Then, the semiconductor chip B is pressed downward toward the copper die pad E by the clamp A.

[0195] Thus, the semiconductor chip B is temporarily fixed to the copper die pad E (see FIG. Figure 2D ).

[0196] The pressure when the semiconductor chip B is pressed against the copper die pad E is preferably 0.01 MPa to 50 MPa, and more preferably 0.1 MPa to 30 MPa.

[0197] It should be noted that the substrate of the adherend of the single piece 2' of the sintered bonding layer can be a lead frame. As the lead frame, a general lead frame can be used. For example, a lead frame in which a silver-plated Cu frame is applied; or a lead frame obtained by sequentially plating Ni, Pd, and Au on a Cu frame (Palladium Pre Plated Lead Frame. Pd-PPF) can be used.

[0198] After performing the above-mentioned operations and temporarily fixing one semiconductor chip B to the copper die pad E, the same operations are repeated.

[0199] In detail, Figure 3A As shown in FIG. 1 , the other semiconductor chips B among the plurality of semiconductor chips B are peeled off from the dicing tape C by the clamper A and lifted up.

[0200] Then, with Figure 2B Similarly, the other semiconductor chip B is pressed by the clamper A against the sintered bonding layer 2 of the sintered bonding sheet 10 .

[0201] Furthermore, with Figure 2C Similarly, the clamper A is lifted up, and the semiconductor chip B in the state of the single piece 2 ′ to which the sintered bonding layer is attached is peeled off from the supporting layer 1 and lifted up.

[0202] Next, the semiconductor chip B in the state of the single piece 2 ′ to which the sintered bonding layer is attached is brought into contact with another mounting region of the copper die pad E while the holder A is held at the same temperature as above.

[0203] And, if Figure 3B As shown, the semiconductor chip B is pressed downward toward the copper die pad E by the clamper A (pressed).

[0204] Thus, the semiconductor chip B is temporarily fixed to the other mounting area of ​​the copper die pad E (see FIG. Figure 3B ).

[0205] The above-mentioned operations are repeatedly performed in sequence until all the semiconductor chips B to be temporarily fixed to the copper die pad E are arranged on the copper die pad E.

[0206] It should be noted that, when temporarily fixing each semiconductor chip B, the clamp A can be heated to a temperature at which the sinterable particles contained in the single piece 2' of the sintered bonding layer can be sintered. Thus, a primary sintering process of the sinterable particles contained in the single piece 2' of the sintered bonding layer can be performed. In other words, just after the temporary fixing as described above, a part of the sintering process can be performed on the single piece 2' of the sintered bonding layer.

[0207] When the sinterable particles contained in the single piece 2' of the sintered bonding layer can be sintered at a heating temperature of 400°C or less, it is preferred to heat the clamp A to a temperature of 200°C or more. By heating the clamp A to 200°C or more, the sinterable particles can be more fully sintered with each other. Therefore, the semiconductor chip B can be more firmly bonded to the copper die pad E by means of the single piece 2' of the sintered bonding layer. In other words, the bonding reliability of the semiconductor chip B to the substrate is further improved.

[0208] When the primary sintering treatment is performed, it is preferred to quickly (about 5 seconds) heat the holder A. The holder A is preferably heated at 30°C / sec or more, more preferably at 45°C / sec or more.

[0209] It should be noted that the above-mentioned primary sintering process can be implemented not only by heating the clamp A, but also by heating the second base H at the same temperature as above. Thus, the single piece 2' of the sintered bonding layer is heated from both sides in the thickness direction, so that the sinterable particles can be sintered more fully with each other. Therefore, the semiconductor chip B can be more fully bonded to the copper chip pad E by means of the single piece 2' of the sintered bonding layer. In other words, the bonding reliability of the semiconductor chip B relative to the substrate is further improved.

[0210] The temperature of the heated second base H is preferably equal to or lower than a temperature that suppresses oxidation of the copper die pad E or the copper thin layer F. The heating temperature of the second base H is preferably 150° C. or lower.

[0211] When the primary sintering process is performed as described above, the temperature of the holder A can be lowered to a temperature (eg, 50° C.) at which the sinterable particles are difficult to sinter by, for example, lifting the holder A upward after the primary sintering process to separate the semiconductor chip B from the holder A.

[0212] It should be noted that, when the single pieces 2 ′ having all sintered bonding layers are subjected to a single sintering process, bonding wires can be bonded to necessary locations after all semiconductor chips B are bonded.

[0213] In the method for manufacturing a semiconductor device described in this embodiment, after temporarily fixing the plurality of semiconductor chips B to the substrate, a heating step of heating the single piece 2' of the sintered bonding layer to a temperature at which the sinterable particles can be sintered can be performed. In the heating step, heating can be performed while applying a compressive force along the thickness direction to at least any one of the single pieces 2' of the plurality of sintered bonding layers.

[0214] When the primary sintering process is performed, the heating step corresponds to the secondary sintering process. In other words, the sintering process can be performed by both the primary sintering process and the secondary sintering process (the heating step).

[0215] More specifically, in the method for manufacturing a semiconductor device according to this embodiment, the sintering process can be performed as follows.

[0216] In the heating step of the sintering treatment, for example, at least one of the plurality of sintered bonding layer sheets 2' is heated while being pressed in the thickness direction. Specifically, after the semiconductor chip B is temporarily fixed, as shown in FIG. Figure 4A As shown in the figure, a heating and pressing device F configured to be heatable can be used to heat the sintered bonding layer single piece 2 ′ while applying a compressive force in the thickness direction.

[0217] For example, the heating and pressurizing device is composed of two flat plates Z, Z. The two flat plates Z, Z are respectively arranged so as to sandwich the second base H, the substrate (ceramic insulating layer D, the copper die pad E and the copper thin layer F), and a plurality of semiconductor chips B temporarily fixed to the copper die pad E by means of the single piece 2' of the sintered bonding layer. Then, by shortening the interval between the two heated flat plates, the plurality of components are pressurized (pressed), so that the single piece 2' of the sintered bonding layer is heated while being pressed.

[0218] By performing the heating step in this way, the single piece 2' of multiple sintered bonding layers can be heated while being pressed, so that the semiconductor chip B can be firmly bonded to the substrate (copper die pad E) by means of the single piece 2' of the sintered bonding layer. Therefore, the bonding reliability of the semiconductor chip B to the substrate can be improved.

[0219] After the heating step is performed in this manner, the bonding wire can be bonded to a necessary location.

[0220] It should be noted that in Figure 4A A tool for arranging a plurality of substrates is disposed between the lower flat plate Z and the copper die pad E shown.

[0221] On the other hand, in the heating process, Figure 4B As shown, after all the semiconductor chips B to be bonded are temporarily fixed, the second base H can be heated without applying a compressive force to the single piece 2' of the sintered bonding layer in the thickness direction. At this time, the second base H is heated at a temperature at which the sinterable particles contained in the single piece 2' of the sintered bonding layer can be sintered (for example, any temperature within the range of 200°C to 400°C).

[0222] Even when such a heating step is performed, the semiconductor chip B can be firmly bonded to the substrate (copper die pad E) via the piece 2' of the sintered bonding layer. Therefore, the bonding reliability of the semiconductor chip B to the substrate can be improved.

[0223] Note that, by performing the heating step as described above, a heating and pressurizing device F for applying a compressive force to the sintered bonding layer piece 2 ′ is not required, so that the manufacturing equipment can be further simplified.

[0224] In the method for manufacturing the semiconductor device described in this embodiment, further steps may be performed.

[0225] For example, a wire bonding step of electrically connecting a part of the semiconductor chip B and a part of the substrate may be performed.

[0226] In addition, a sealing step may be performed to seal the semiconductor chip B and the sintered bonding layer piece 2' with a thermosetting resin such as epoxy resin. In the sealing step, a heat treatment is performed at a temperature of 150°C to 200°C, for example, to promote a curing reaction of the thermosetting resin.

[0227] In the method for manufacturing a semiconductor device according to this embodiment, as described above, for example, a sintering process is performed in which the piece 2 ′ of the sintered bonding layer is heated while applying a compressive force in the thickness direction to bond the piece 2 ′ of the sintered bonding layer to the substrate.

[0228] As described above, in the sintered bonding layer 2, in the observation image obtained by observing the surface at 100 times, the largest size of the voids observed is 100 μm or less. 2 In the range of , the area ratio of the voids is less than 5.0%. The sintered bonding layer 2 has such a structure, so the maximum size of the voids is small, and sometimes there are basically no voids. Therefore, after undergoing the sintering process, the maximum size of the voids in the sintered bonding layer 2 also becomes smaller, and sometimes the voids may disappear. Therefore, even if the sintered bonding layer 2 is repeatedly subjected to temperature increases and decreases during use, at a part of the interface between the sintered bonding layer 2 and the adherend, peeling caused by the above-mentioned voids can at least be suppressed. In addition, inside the sintered bonding layer 2, the generation of cracks caused by the above-mentioned voids can at least be suppressed. Therefore, even if the sintered bonding layer 2 is repeatedly subjected to temperature increases and decreases during use, the bonding between the sintered bonding layer 2 and the adherend can be fully maintained.

[0229] The sintered bonding sheet of the present embodiment is as exemplified above, but the present invention is not limited to the sintered bonding sheet and the like exemplified above.

[0230] That is, various forms used in general sintered bonding sheets and the like can be adopted within a range that does not impair the effects of the present invention.

[0231] The matters disclosed in this specification include the following technical solutions.

[0232] (1) A sheet for sintered bonding, comprising a sintered bonding layer, the sintered bonding layer comprising an organic binder and sinterable particles containing a conductive metal,

[0233] In an observation image obtained by observing the surface of the sintered bonding layer at 100 times magnification, the largest size of the voids observed was 100 μm or less.

[0234] The sinter bonding sheet having the above-mentioned structure can maintain sufficient bonding with an adherend even when used in an environment where the temperature repeatedly rises and falls.

[0235] (2) The sheet for sinter bonding according to (1) above, wherein at least 9 mm of the observed image 2 Within the range of , the area ratio of the above-mentioned gaps is 5.0% or less.

[0236] (3) The sintered bonding sheet according to (1) or (2), wherein the complex viscosity of the sintered bonding layer at 25°C is 3×10 5 [Pa·s] or more and 3×10 11 [Pa·s] or less.

[0237] (4) The sintered bonding sheet according to any one of (1) to (3) above, wherein the complex viscosity of the sintered bonding layer is 3×10 4 [Pa·s] or more and 3×10 10 [Pa·s] or less.

[0238] (5) The sintered bonding sheet according to any one of (1) to (4) above, wherein the average particle size of the sinterable particles is 1 nm to 10,000 nm, preferably 50 nm to 500 nm.

[0239] (6) The sintered bonding sheet according to any one of (1) to (5), wherein the sintered bonding layer contains a first organic binder and a second organic binder having a molecular weight smaller than that of the first organic binder as the organic binder.

[0240] (7) The sintered bonding sheet according to (6) above, wherein the first organic binder is a thermally decomposable polymer binder.

[0241] (8) The sintered bonding sheet according to any one of (1) to (7), wherein the sintered bonding layer contains 60% by mass or more and 99% by mass or less of the sinterable particles.

[0242] (9) The sintered bonding sheet according to any one of (1) to (8), wherein the sintered bonding layer contains 1% by mass or more and 40% by mass or less of the organic binder.

[0243] (10) A method for producing a sintered-bonding sheet, which is a method for producing a sintered-bonding sheet according to any one of (1) to (9), comprising:

[0244] a step of preparing a varnish comprising the sinterable particles, the organic binder and an organic solvent; and

[0245] A step of volatilizing the organic solvent from the varnish to form the sintered bonding layer.

[0246] Example

[0247] Next, the present invention will be described in more detail by way of experimental examples. However, the following examples are for describing the present invention in more detail and are not intended to limit the scope of the present invention.

[0248] (Raw materials for sintered bonding layer)

[0249] [Sintered particles]

[0250] First Silver Particles:

[0251] Average particle size: 60 nm, manufactured by DOWA ELECTRONICS

[0252] Second silver particles:

[0253] Average particle size 1100nm, manufactured by Mitsui Mining and Smelting Co., Ltd.

[0254] [Organic binder]

[0255] ·First organic binder (thermodegradable polymer binder): polycarbonate resin:

[0256] (Biphenyl type phenolic resin, phenol equivalent is 209g / eq)

[0257] Product name: "QPAC40", manufactured by Empower Materials

[0258] Second organic binder (volatile binder): isobornyl cyclohexanol

[0259] Product name: Terusolve MTPH, manufactured by NIPPON TERPENE CHEMICALS

[0260] Organic solvent: methyl ethyl ketone (MEK)

[0261] (Supporting layer)

[0262] Release film (product name "MRA38", made by Mitsui Plastics Co., Ltd.)

[0263] (Example 1)

[0264] The first silver particles, the second silver particles, the first organic binder (polycarbonate resin), and the second organic binder (isobornylcyclohexanol) were dissolved or suspended in methyl ethyl ketone (MEK) in the blending composition shown in Table 1 to prepare a varnish. Specifically, a mixing stirrer (model: "HM-500", manufactured by Keyence Corporation) was used to stir the mixture for 3 minutes in a stirring mode.

[0265] Next, a varnish was applied to the release-treated surface of the support layer, and then heated at 110° C. for 3 minutes to form a sintered bonding layer on the support layer. In this manner, an intermediate product of a sintered bonding sheet was produced.

[0266] Next, two intermediate sheets for sintered bonding were bonded together so that the sintered bonding layers overlapped each other, thereby manufacturing a sheet for sintered bonding having a sintered bonding layer with a thickness of 50 μm.

[0267] In addition, in Table 1, the compounding amount of the first silver particles and the second silver particles is expressed as the amount at the time of charging, and in Table 2, the compounding amount of the sinterable particles is expressed as the value of ash content.

[0268] [Table 1]

[0269]

[0270] [Table 2]

[0271] Unit: parts by mass (solid content 100 parts by mass)

[0272] Varnish composition Composition A Component B Composition C Sintered particles 93 92 90 Organic binder 7 8 10

[0273] The viscosity of each varnish of composition A, composition B and composition C was measured under the above-mentioned measurement conditions.

[0274] (Examples 2 to 7)

[0275] Except for changing the compounding composition to that shown in Table 3, the same operation as above was carried out to produce each sheet for sinter bonding.

[0276] (Comparative Examples 1 and 2)

[0277] Except for changing the compounding composition to that shown in Table 3, the same operation as above was carried out to produce each sheet for sinter bonding.

[0278] The compositions and physical properties of the sintered bonding sheets in the respective Examples and Comparative Examples are shown in Table 3, respectively.

[0279] [Table 3]

[0280]

[0281] <Physical Properties of Sintered Bonding Sheet (Sintered Bonding Layer)>

[0282] The surface observation and physical property measurement of the sintered bonding layer of each sintered bonding sheet produced as described above were performed as follows.

[0283] [Complex viscosity of sintered bonding layer]

[0284] The complex viscosity of the sintered bonding layer was measured under the following measurement conditions.

[0285] Test piece cut out from the sintered bonding layer: 30 mm long, 5 mm wide

[0286] Measuring device: Dynamic viscoelasticity measuring device

[0287] (Product name: "RSA-G2" (manufactured by TA Instruments, etc.)

[0288] Measurement mode: Stretch mode

[0289] Initial distance between chucks: 20mm

[0290] Stretching speed: 1mm / sec

[0291] Measurement temperature: from 10°C to 100°C (heating rate: 5°C / min)

[0292] At least the value [Pa·s] of the complex viscosity (complex viscosity ratio η*) at 25°C is read.

[0293] [Surface observation and image analysis of sintered bonding layer]

[0294] Device used: Digital microscope, machine name "VHX-2000", manufactured by KEYENCE Corporation

[0295] Lens: Z20, set to 100x

[0296] Shutter speed: 1 / 60[sec]

[0297] Gain: 0[dB]

[0298] Lighting: Turn on the light (about 90%), the base is turned on through the lighting (about 20%)

[0299] Frame rate: 15”F / s”

[0300] The image was taken under the above conditions. In addition, the saturation histogram was extracted for the image taken (extraction range: saturation 0 to 50) to obtain an observed image. The image was analyzed using the automatic area measurement function of the device. The area of ​​the image to be analyzed was about 9.7 mm. 2 Based on the obtained analysis results, the maximum size of the plurality of voids and the total area ratio of the voids are obtained. It should be noted that the size of each void is the distance between two points that are farthest from each other when a straight line is formed.

[0301] The following are image examples (Examples 1 to 4 and Comparative Examples 1 and 2) in which the observed images are binarized for image analysis. Figure 5A to Figure 5C .

[0302] <Reliability Evaluation of Sintered Bonding Sheet (Sintered Bonding Layer)>

[0303] In order to confirm the ease of peeling at the interface between the sintered bonding layer and a part of the adherend after repeated temperature rise and fall, the sintered bonding layer of each sintered bonding sheet manufactured as above is evaluated respectively by the following operation. If briefly described, a stacked body (package) having a sintered bonding layer is assembled, and then a temperature cycle test is performed on the stacked body, and the bonding state of the sintered bonding layer is evaluated using an ultrasonic flaw detection image. The details are as follows.

[0304] A Cu substrate (20 mm × 20 mm × 3 mm thick) plated with silver at a thickness of 5 μm and a Si chip (5 mm × 5 mm × 0.2 mm thick) plated with Ti (0.1 μm thick) / Ag (0.75 μm thick) were prepared. The Cu substrate and the Si chip were used to sandwich each sintered bonding layer to produce a stacked body, and the sintering bonding process was performed under the conditions of 300°C / 10 MPa / 2.5 minutes.

[0305] The laminated body after the sintering process was evaluated for the bonding state (area of ​​the region bonded with the sintering bonding layer) at the interface between the Cu substrate and the sintering bonding layer and at the interface between the Si chip and the sintering bonding layer using ultrasonic flaw detection images (initial evaluation).

[0306] Device: "FineSAT200", manufactured by HITACHIPOWER SOLUTIONS

[0307] Probe: PQ2-50-13 (reflection mode)

[0308] Number of measurement points: 600×600 (square area with a side length of 21 mm)

[0309] After the above initial evaluation, the laminate was placed in a temperature cycle tester and subjected to a degradation acceleration test by repeatedly increasing and decreasing the temperature under the following conditions.

[0310] Temperature conditions: -40℃ / 200℃ (no time left at room temperature, repeated every 15 minutes)

[0311] Number of cycles: 1000 cycles

[0312] The laminate after the degradation acceleration test was evaluated based on the ultrasonic flaw detection image using the same method as above. Specifically, the evaluation was performed using image analysis software ("Image J") to compare the bonding area obtained by the initial evaluation with the bonding area obtained by the evaluation after the degradation acceleration test. When the bonding area in the initial evaluation is set to 100%, if the bonding area after the degradation acceleration test is less than 50% (the peeling of the sintered bonding layer is carried out to more than half of the bonding area), the reliability evaluation is judged as "poor". Otherwise, it is judged as "good".

[0313] As can be determined from the above evaluation results, the sintered bonding layer of the sintered bonding sheet of the embodiment can suppress peeling at a part of the interface between the sintered bonding layer and the adherend even when used in an environment where the temperature rises and falls repeatedly. That is, it has good bonding reliability. It should be noted that the sintered bonding layer of the sintered bonding sheet of the embodiment also has good thermal conductivity and electrical conductivity.

[0314] On the other hand, the sintered bonding layer of the sintered bonding sheet of the comparative example did not have good bonding reliability.

[0315] Industrial Applicability

[0316] The sinter bonding sheet of the present invention can be suitably used as an auxiliary tool in manufacturing a semiconductor device, for example.

Claims

1. A sheet for sintered bonding, comprising a sintered bonding layer, the sintered bonding layer comprising an organic binder and sinterable particles containing a conductive metal, In an observation image obtained by observing the surface of the sintered bonding layer at a magnification of 100, the largest size of the voids observed was 100 μm or less.

2. The sheet for sintering bonding according to claim 1, wherein At least 9 mm of the observed image 2 Within the range of , the area ratio of the voids is 5.0% or less.

3. The sheet for sintering bonding according to claim 1 or 2, wherein The complex viscosity of the sintered bonding layer at 25°C is 3.0×10 6 [Pa·s] or more and 3.0×10 10 [Pa·s] or less.

4. The sheet for sintering bonding according to claim 1 or 2, wherein The sintered bonding layer contains 60 mass % or more and 99 mass % or less of the sinterable particles.

5. The sheet for sintering bonding according to claim 1 or 2, wherein The average particle size of the sinterable particles is 50 nm or more and 500 nm or less.

Images