Sheet for sintering bonding and method for producing sheet for sintering bonding

Abstract

An object of the present invention is to provide a sheet for sintering bonding having good transferability of a sintering bonding layer to a semiconductor chip, and capable of suppressing peeling and floating of a base material layer from the sintering bonding layer.SOLUTION: And a base material layer overlapping at least one of surfaces of the sintered joining layer, in which the surfaces of the sintered joining layer overlapping the base material layer have a roughness Ra of 10. 5nm or more and 90. 0nm or less.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a sheet for sinter bonding used, for example, in manufacturing a semiconductor device, and also to a method for manufacturing the sheet for sinter bonding. [Background technology]

[0002] Sinter-bonding sheets used in the manufacture of semiconductor devices have been known. These sheets have a sinter-bonding layer containing sinterable particles containing conductive metal and an organic binder. The sinter-bonding layer has pressure-sensitive adhesive properties due to the organic binder. In manufacturing a semiconductor device, the above-mentioned sintered bonding layer is placed between one surface of a substrate and a semiconductor element (such as a semiconductor chip), and a sintering process is performed, thereby bonding the substrate and the semiconductor element via the sintered bonding layer. For example, the following steps are carried out to manufacture a semiconductor device.

[0003] (1) A semiconductor wafer is attached and fixed onto the adhesive layer of a dicing tape, which is made by laminating a support layer and an adhesive layer, and then the semiconductor wafer is diced into a plurality of individual semiconductor elements. (2) After peeling and lifting one semiconductor element from the adhesive layer using a jig such as a collet, the semiconductor element is pressed onto the sintered bonding layer of the sintered bonding sheet. This pressing force separates a portion of the sintered bonding layer into individual pieces corresponding to the size of the semiconductor element. At the same time, the individual pieces of the sintered bonding layer are adhered to the semiconductor element, and the jig such as a collet is lifted up to pick up one semiconductor element to which the individual pieces of the sintered bonding layer are adhered. Hereinafter, the ability to perform such pickup well is also referred to as "good transferability to semiconductor chips." (3) One semiconductor element with the piece of sintered bonding layer bonded thereto is bonded to one surface of the substrate (the semiconductor element mounting area). In other words, one semiconductor element is temporarily fixed to the substrate. (4) By repeating steps (2) and (3) above multiple times, multiple semiconductor elements with individual pieces of the sintered bonding layer bonded thereto are temporarily fixed in the semiconductor element mounting area of ​​the substrate, thereby obtaining an intermediate semiconductor device. (5) By performing a sintering process in which the intermediate semiconductor device product is heated to a temperature at which the sinterable particles in the sintered bonding layer can be sintered together, the sinterable particles are sintered together while at least a portion of the organic binder is removed from the sintered bonding layer, thereby bonding multiple semiconductor elements to the semiconductor element mounting area of ​​the substrate. After the above-described processes, the semiconductor elements are fixed in the semiconductor element mounting area of ​​the substrate by the sintering of the sinterable particles contained in the sintered bonding layer. That is, the semiconductor elements are fixed in the semiconductor element mounting area of ​​the substrate via the individual pieces of the sintered bonding layer that have undergone the sintering process.

[0004] In the manufacture of a semiconductor device, instead of carrying out the above steps (1) and (2), it is also possible to overlay a sintered bonding layer on the adhesive layer of a dicing tape, and then attach a semiconductor wafer to it, separate the sintered bonding layer and the semiconductor wafer, and pick up the semiconductor element with the sintered bonding layer attached.

[0005] As a sinter bonding sheet that can be used in the manufacturing method of the semiconductor device described above, for example, a wound body having a sinter bonding layer that becomes a strong sintered layer after sintering processing and a base layer is known (for example, Patent Document 1).

[0006] In detail, the wound body described in Patent Document 1 is a wound laminate of a sintered bonding layer and a base material layer, the thickness of the laminate is 10 to 300 μm, and the surface roughness of the sintered bonding layer that overlaps the base material layer is, for example, 50 μm or less. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-147706 Summary of the Invention [Problem to be solved by the invention]

[0008] If the laminate described in Patent Document 1 (a laminate of a sintered bonding layer and a base layer) is simply used to perform the pickup described above, good delamination between the sintered bonding layer and the base layer may not occur, causing wrinkles in the sintered bonding layer and resulting in poor transferability. Meanwhile, since the adhesion between the sintered bonding layer and the base layer is not necessarily good, the base layer may peel off from the sintered bonding layer and float when the laminate is wound, for example. Thus, good transferability is not necessarily achieved when the above-described pickup is performed simply using the laminate of the sintered bonding layer and the base material layer described in Patent Document 1. Furthermore, the laminate of the sintered bonding layer and the base material layer described in Patent Document 1 does not necessarily prevent the base material layer from peeling off and floating from the sintered bonding layer.

[0009] However, it cannot be said that sufficient research has yet been conducted into sinter bonding sheets that have good transferability of the sinter bonding layer to the semiconductor chip and can prevent the base layer from peeling off and floating away from the sinter bonding layer.

[0010] Therefore, an object of the present invention is to provide a sheet for sintering bonding that has good transferability of a sintering bonding layer to a semiconductor chip and can prevent the base layer from peeling off and floating from the sintering bonding layer. [Means for solving the problem]

[0011] In order to solve the above problems, the sinter-bonding sheet according to the present invention is a sintered bonding layer including sinterable particles containing a conductive metal and an organic binder; a base layer overlapping at least one surface of the sintered bonding layer, The surface of the sintered bonding layer overlapping the base layer has a surface roughness Ra of 10.5 nm or more and 90.0 nm or less.

[0012] The method for producing a sinter bonding sheet according to the present invention is a method for producing a sinter bonding sheet including a sinter bonding layer containing sinterable particles containing a conductive metal and an organic binder, and a base layer overlapping at least one surface of the sinter bonding layer, forming a plurality of intermediate bodies of the sintered bonding layer into a sheet shape by volatilizing the solvent from a varnish containing the sinterable particles, the organic binder, and a solvent; and applying a press treatment to the sintered bonding layer produced by bonding the plurality of intermediate bodies together, In the pressing process, a pressure of 0.1 MPa to 10.0 MPa is applied at a temperature of 30° C. to 150° C. with the base layer in contact with at least one surface of the sintered bonding layer. [Effects of the Invention]

[0013] The sintering bonding sheet and the manufacturing method of the sintering bonding sheet of the present invention can provide a sintering bonding sheet that has good transferability of the sintering bonding layer to the semiconductor chip and can prevent the base layer from peeling off and floating away from the sintering bonding layer. [Brief explanation of the drawings]

[0014] [Figure 1A] 1 is a schematic cross-sectional view of a sinter-bonding sheet according to an embodiment of the present invention cut in the thickness direction. [Figure 1B] 2 is a schematic cross-sectional view of a portion of the rolled sinter-bonding sheet of the present embodiment, cut in the thickness direction. FIG. [Figure 2A] 1 is a schematic cross-sectional view showing a part of a specific example of manufacturing equipment for carrying out the manufacturing method of a sheet for sinter bonding of the present embodiment. [Figure 2B] 1 is a schematic cross-sectional view showing a part of a specific example of manufacturing equipment for carrying out the manufacturing method of a sheet for sinter bonding of the present embodiment. [Figure 2C] 1 is a schematic cross-sectional view showing a part of a specific example of manufacturing equipment for carrying out the manufacturing method of a sheet for sinter bonding of the present embodiment. [Figure 3A]FIG. 10 is a schematic cross-sectional view showing how one semiconductor chip is lifted from the dicing tape by a collet. [Figure 3B] 10 is a schematic cross-sectional view showing a state in which a part of the sinter bonding layer of the sinter bonding sheet is divided into individual pieces. FIG. [Figure 3C] 10 is a schematic cross-sectional view showing a state in which a part of the sinter bonding layer of the sinter bonding sheet is divided into individual pieces. FIG. [Figure 3D] 10 is a schematic cross-sectional view showing a state in which one semiconductor chip to which an individual piece of the sintered bonding layer is attached is temporarily fixed to a substrate. [Figure 4A] FIG. 10 is a schematic cross-sectional view showing how another semiconductor chip is lifted from the dicing tape by the collet. [Figure 4B] 10 is a schematic cross-sectional view showing how another semiconductor chip having an individual piece of the sintered bonding layer attached thereto is temporarily fixed to a substrate. [Figure 5A] 10 is a schematic cross-sectional view showing an example of heating the individual pieces of the sintered bonding layer while pressing them. FIG. [Figure 5B] FIG. 10 is a schematic cross-sectional view showing another example of heating the individual pieces of the sintered bonding layer without pressing them. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, one embodiment of the sintering bonding sheet according to the present invention will be described with reference to the drawings.

[0016] As shown in FIGS. 1A and 1B, the sinter bonding sheet 10 according to this embodiment includes a sinter bonding layer 2 containing sinterable particles containing a conductive metal and an organic binder. A base material layer 1 is superimposed on at least one surface (one or both surfaces) of the sinter bonding layer 2. The sinter bonding sheet 10 according to this embodiment is, for example, in the form of a long strip. The sinter bonding sheet 10 according to this embodiment may be stored in a cylindrically rolled state.

[0017] [Sintered bonding layer of sintered bonding sheet] The sintered bonding layer 2 has pressure-sensitive adhesive properties because it contains an organic binder, and therefore can be temporarily bonded to an adherend when pressure is applied. Furthermore, when the sintered bonding layer 2 is subjected to a sintering process, the sinterable particles inside are sintered together. The sintered bonding layer 2 after the sintering process is disposed, for example, between a substrate and a semiconductor chip B to bond them together. In the sintered bonding layer 2 after the sintering process, at least a portion of the organic binder has disappeared. It is preferable that almost no organic binder remains in the sintered bonding layer 2 after the sintering process, and more preferably that no organic binder remains at all.

[0018] The surface roughness Ra of at least one surface of the sintered bonding layer 2 (the surface overlapping the base layer 1) is 10.5 nm or more and 90.0 nm or less. As will be explained in detail later, the sintered bonding layer 2 having such a configuration has good transferability to semiconductor chips. Furthermore, the sintered bonding sheet 10 including the sintered bonding layer 2 having such a configuration can prevent the base layer 1 from peeling off and floating from the sintered bonding layer 2. If the surface roughness Ra is less than 10.5 nm, when a semiconductor element is pressed against the sintered bonding layer 2 overlying the base layer 1 and then the semiconductor chip with the singulated sintered bonding layer 2 adhered thereto is picked up, good separation does not occur between the singulated sintered bonding layer 2 and the base layer 1, and wrinkles may occur in the sintered bonding layer 2. Therefore, good transferability to the semiconductor chip is not achieved. On the other hand, if the surface roughness Ra exceeds 90.0 nm, the adhesion between the base material layer 1 and the sintered bonding layer 2 will be poor, resulting in poor individualization of the sintered bonding layer 2 when a single semiconductor element is pressed against it, and poor transferability to the semiconductor chip will not be achieved. Furthermore, because the adhesion between the base material layer 1 and the sintered bonding layer 2 is poor, peeling is likely to occur between the base material layer 1 and the sintered bonding layer 2 when the sintered bonding sheet 10 is bent, for example. In other words, the base material layer 1 will likely lift off the sintered bonding layer 2. 1A and 1B, when two base layers 1 overlap each other on both surfaces of the sintered bonding layer 2, the surface roughness Ra of one surface may be 10.5 nm or more and 90.0 nm or less, or both surfaces may have surface roughness Ra of 10.5 nm or more and 90.0 nm or less. On the other hand, when one base layer 1 overlaps one surface of the sintered bonding layer 2, the surface overlapping the base layer 1 has a surface roughness Ra of 10.5 nm or more and 90.0 nm or less.

[0019] The surface roughness Ra is preferably 12.0 nm or more, and more preferably 14.0 nm or more. A larger surface roughness Ra can improve the transferability of the sintered bonding layer 2 to the semiconductor chip. Meanwhile, the surface roughness Ra is preferably 40.0 nm or less, more preferably 25.0 nm or less, and even more preferably 20.0 nm or less. A smaller surface roughness Ra can improve the transferability of the sintered bonding layer 2 to the semiconductor chip. Furthermore, lifting of the base layer 1 from the sintered bonding layer 2 can be further suppressed.

[0020] The surface roughness Ra can be adjusted, for example, by changing the average particle size of the sinterable particles blended into the varnish when producing the sintered bonding layer 2. Specifically, by setting the average particle size (D50) of the sinterable particles to preferably 0.01 μm or more and 10.0 μm or less, more preferably 0.05 μm or more and 3.0 μm or less, the surface roughness Ra can be more easily set to 10.5 nm or more and 90.0 nm or less. Furthermore, the surface roughness Ra can be adjusted by, for example, changing the bonding conditions (pressing conditions) for the sinter bonding layer 2 and the base layer 1 when producing the sinter bonding sheet 10. Specifically, the pressure in the pressing process can be set to preferably 0.1 MPa to 10.0 MPa, more preferably 0.5 MPa to 3.0 MPa, to more easily achieve the surface roughness Ra of 10.5 nm to 90.0 nm. Alternatively, the temperature in the pressing process can be set to preferably 30°C to 150°C, more preferably 70°C to 100°C, to more easily achieve the surface roughness Ra of 10.5 nm to 90.0 nm. Alternatively, the surface roughness Ra can be set to 10.5 nm to 90.0 nm by employing a continuous roll pressing process in the pressing process and setting the continuous feed rate to preferably 0.1 m / min to 3.0 m / min, more preferably 0.5 m / min to 2.5 m / min, to more easily achieve the surface roughness Ra of 10.5 nm to 90.0 nm. The method for producing the sinter-bonding sheet 10 will be described in detail later.

[0021] [Method for measuring surface roughness Ra of sintered bonding layer] The surface roughness Ra of the sintered bonding layer 2 is measured as follows. An electron microscope image (SEM image, 50,000x magnification) of a cross section of the sintered bonding layer cut in the thickness direction is obtained. Using image analysis software (e.g., product name "ImageJ"), a drawing is performed along the surface irregularities, and the average line is determined from the resulting drawing curve (roughness curve). A reference length (L) is set along the direction of the average line. The absolute values ​​of the deviations from the average line extending along the set reference length (L) to the drawing curve are summed. The average of the summed values ​​is calculated as the surface roughness Ra (arithmetic mean roughness). A predetermined value between 2.0 μm and 5.0 μm is used as the reference length (L). The surface roughness Ra can be determined in accordance with JIS B0601 (1994) and JIS B0031 (1994).

[0022] The conductive metal contained in the sintered particles has an electrical conductivity of 100 [μS / cm] or more (10 6 It is a metal with a dielectric constant of 0.1 [S / m] or more. Examples of conductive metals 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. The sinterable particles may include metal oxides such as silver oxide, copper oxide, palladium oxide, and tin oxide.

[0023] In this embodiment, the sinterable particles preferably contain at least one selected from the group consisting of silver, copper, silver oxide, and copper oxide. This can improve the bonding strength when bonding a semiconductor element to a substrate via the individualized sintered bonding layer 2 (individual sintered bonding layer piece 2"), as described below.

[0024] The sinterable particles preferably contain at least one of silver and copper as the conductive metal, which can improve the thermal conductivity and electrical conductivity of the sintered bonding layer 2.

[0025] 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 carried out even in an air atmosphere. More specifically, for example, the sintering process when bonding a semiconductor element such as a semiconductor chip B to a substrate can be suitably carried out in an air atmosphere. On the other hand, when the sinterable particles contain, for example, copper, the sintering process is desirably carried out in an inert environment such as a nitrogen atmosphere to prevent oxidation of the copper.

[0026] The sinterable particles may contain a metal oxide, for example, the sinterable particles may be metal particles whose surface layers have been converted into a metal oxide.

[0027] 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 primary component. The shell portion may contain gold, silver, silver oxide, or copper oxide as a primary component. For example, the sinterable particles may be in a state where at least a portion of the surface of a silver particle is covered with silver oxide, or in a state where at least a portion of the surface of a copper particle is covered with copper oxide. More specifically, the particles formed of multiple types of metals may be particles having a core portion formed of, for example, 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.

[0028] In addition, examples of sinterable particles include composite particles containing a metal and a non-metallic material. Examples of composite particles include particles having a core formed of resin particles or the like 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. The core may be formed of a carbon material such as carbon black or carbon nanotubes.

[0029] The metal particles as sinterable particles may be surface-treated (e.g., silane coupling treatment). Examples of surface treatment agents for metal particles include fatty acid-based coating agents, amine-based coating agents, and epoxy-based coating agents. For example, metal particles surface-treated with fatty acids (which are also the above-mentioned composite particles) can be used.

[0030] When the sinterable particles contain silver, more specifically, when the sinterable particles are silver particles, the silver particles may contain elemental silver and other elements (such as metal elements) that are unavoidable impurity elements. Silver particles whose surfaces have been treated with a coating agent (hereinafter, sometimes referred to as "coating-treated silver particles") are preferred for the following reasons. By using coating-treated silver particles as the sinterable particles, the affinity between the organic binder and the sinterable particles can be further increased in the sintered bonding layer 2 before the sintering process. This allows the sinterable particles to be more thoroughly dispersed in the sintered bonding layer 2 before the sintering process. As will be explained later regarding the manufacture of a semiconductor device, by subjecting the sintered bonding layer 2 to a sintering treatment at a predetermined temperature or higher, at least a portion of the organic binder disappears from the sintered bonding layer 2.

[0031] The above sinterable particles may be used alone or in combination of two or more types.

[0032] The shape of the sinterable particles is, for example, needle-like, thread-like, spherical, or plate-like (including scale-like), etc. Of these shapes, the spherical shape is preferred. When the sinterable particles are spherical, the sinterable particles can be more favorably dispersed in the varnish used to obtain the sintered bonding layer 2, which will be described later.

[0033] The sinterable particles are sintered together by a sintering process in which they are heated to a predetermined temperature. The sinterable particles are particles in which at least a portion of each particle is made of the conductive metal and which adhere to each other when heated at a predetermined temperature. Therefore, a heat transfer path is formed inside the sintered bonding layer 2 by the sintering process. In particular, a heat transfer path is formed in the thickness direction. This allows the thermal conductivity (heat dissipation) of the sintered bonding layer 2 to be relatively high.

[0034] The sinterable particles may be sinterable at a heating temperature of 400° C. or less. In other words, sinterable particles that exhibit necking on their outer surfaces when heated at a temperature of 400° C. or less may be used. Preferably, the sinterable particles are sinterable at a heating temperature of 300° C. or less.

[0035] The temperature at which the sinterable particles sinter can be measured using a thermogravimetric differential thermal analyzer. Specifically, measurements are performed using a thermogravimetric differential thermal analyzer (e.g., a Rigaku TG8120 differential thermobalance) under the following conditions. A Tg curve and a DTA curve are obtained from the measurements. The temperature of the largest peak in the DTA curve observed near the bottom of the Tg curve is taken as the sintering temperature of the sinterable particles. <Measurement conditions> Heating rate: 10℃ / min Measurement atmosphere: Air Measurement temperature range: from room temperature (23±2°C) to 500°C

[0036] Sinterable particles containing conductive metals such as gold, silver, copper, palladium, tin, nickel, and alloys thereof can be sintered at a heating temperature of 400° C. or less.

[0037] The average particle size of the sinterable particles is preferably 0.01 μm or more, and more preferably 0.05 μm or more. This can improve the dispersibility of the sinterable particles in the varnish used to obtain the sintered bonding layer 2 described below. Therefore, the sintered bonding layer 2 in which the sinterable particles are sufficiently dispersed can be produced from the varnish. On the other hand, the average particle size of the sinterable particles is preferably 10 μm or less, and more preferably 5 μm or less, which allows the sintered bonding layer 2 to have a smoother surface.

[0038] The average particle size of the sinterable particles is determined by observing the cross section of the sintered bonding layer 2 using a scanning electron microscope (SEM). Specifically, it is determined according to the following procedure. The following procedure is performed on the sintered bonding layer 2 before it is subjected to a sintering treatment (described later). (1) A sintered bonding layer 2 having a size of 10 mm×10 mm when viewed in a direction perpendicular to the thickness direction and a thickness of 50 μm (0.05 mm) is prepared as a measurement sample. (2) The measurement sample is cut and the cross section is subjected to a surface preparation process, and then a conductive treatment is performed to prepare a sample for SEM observation. (3) Obtain an SEM observation image (at a magnification of 10,000 or 100,000 times depending on the size of each particle) at an accelerating voltage of 3 kV. (4) Image analysis is performed on the SEM observation image to identify each particle. Particles present on the edge of the observation image are excluded. The circle-equivalent diameter of each identified particle is calculated. The circle-equivalent diameter is the diameter of a perfect circle calculated from the area of ​​each particle, assuming that each particle is a perfect circle.

[0039] The sintered bonding layer 2 preferably contains 70% by mass or more of sinterable particles, more preferably 75% by mass or more, and even more preferably 80% by mass or more, and preferably 99% by mass or less of sinterable particles, more preferably 98% by mass or less, and even more preferably 97% by mass or less. By ensuring that the content of sinterable particles is within the above range, when the sinterable particles are sintered together by a sintering process to bond a semiconductor element such as a semiconductor chip B to a substrate, the bonding by the sintered bonding layer 2 after the sintering process can exhibit sufficient reliability.

[0040] The content of sinterable particles in the sintered bonding layer 2 can be calculated from the measured amount of ash remaining after burning the sintered bonding layer 2. For example, the measurement can be carried out using a thermogravimetric analyzer (e.g., TG209F1) according to the following procedure. Note that the measurement using the thermogravimetric analyzer is preferably carried out under a nitrogen gas flow. (1) A measurement sample of the sintered bonding layer 2 weighed to about 50 mg is heated from room temperature (23±2°C) to 650°C. (2) The organic binder in the measurement sample is thermally decomposed by holding it at a temperature of 650°C for 30 minutes. (3) Calculate the mass ratio of the remaining components (ash) to the weighed value of the measurement sample (approximately 50 mg).

[0041] In this embodiment, the sintered bonding layer 2 preferably contains, as organic binders, a first organic binder and a second organic binder having a smaller molecular weight than the first organic binder.

[0042] The first organic binder is preferably a thermally decomposable polymer binder. The thermally decomposable polymer binder is a binder that is thermally decomposed by the sintering process. The thermally decomposable polymer binder also has the function of maintaining the sintered bonding layer 2 in a sheet shape before the sintering process. From the viewpoint of more fully exerting this function, the thermally decomposable polymer binder is preferably solid at room temperature (23±2°C). Examples of the thermally decomposable polymer binder include polycarbonate resin and acrylic resin. The sintered bonding layer 2 preferably contains at least one of polycarbonate resin and acrylic resin as the first organic binder. The sintered bonding layer 2 may contain only polycarbonate resin as the first organic binder.

[0043] Examples of polycarbonate resins include aliphatic polycarbonates that have only aliphatic chains and do not contain aromatic structures such as benzene rings between the carbonate esters (-O-CO-O-) in the main chain, and aromatic polycarbonates that contain aromatic structures between the carbonate esters (-O-CO-O-) in the main chain. Examples of the aliphatic polycarbonate include polyethylene carbonate and polypropylene carbonate. Examples of aromatic polycarbonates include polycarbonates containing a bisphenol A structure in the main chain.

[0044] Examples of the acrylic resin include polymers of (meth)acrylic acid alkyl esters in which the carbon number of the linear or branched alkyl moiety is 4 to 18. The term "(meth)acrylic" encompasses both "acrylic" and "methacrylic."

[0045] Examples of the alkyl group (alkyl moiety) of the (meth)acrylic acid ester include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an isobutyl group, an amyl group, an isoamyl group, a hexyl group, a heptyl group, a cyclohexyl group, a 2-ethylhexyl group, an octyl group, an isooctyl group, a nonyl group, an isononyl group, a decyl group, an isodecyl group, an undecyl group, a lauryl group, a tridecyl group, a tetradecyl group, a stearyl group, and an octadecyl group.

[0046] The acrylic resin may have in its molecule a polymerization unit derived from a monomer other than the (meth)acrylic acid ester, such as a carboxyl group-containing monomer, an acid anhydride monomer, a hydroxyl group-containing monomer, a sulfonic acid group-containing monomer, or a phosphoric acid group-containing monomer.

[0047] Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride. Examples of hydroxy group-containing monomers 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. Examples of sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

[0048] The second organic binder that can be contained in the sintered bonding layer 2 is preferably a volatile binder. The volatile binder is a binder component that, when measured by thermogravimetric analysis (TGA), undergoes complete weight loss (is completely eliminated to 0% by weight) at a temperature lower than that of the first organic binder (for example, the above-mentioned thermally decomposable polymer binder).

[0049] In this embodiment, the volatile binder has a viscosity of 1×10 at 23° C. 5 It is preferable that the viscosity is a liquid having a viscosity of Pa·s or less. Such viscosity is measured using a dynamic viscoelasticity measuring device (device name "HAAKE MARS III", manufactured by Thermo Fisher Scientific). Specifically, parallel plates of 20 mm diameter are used as a jig, the gap between the plates is set to 100 μm, and the shear rate in rotational shear is set to 1 s -1 The viscosity is measured as follows.

[0050] Examples of the easily volatile binder include terpene alcohols, alcohols other than terpene alcohols, alkylene glycol alkyl ethers, and ethers other than alkylene glycol alkyl ethers.

[0051] Examples of terpene alcohols include isobornylcyclohexanol, citronellol, geraniol, nerol, carveol, and α-terpineol. Examples of alcohols other than terpene alcohols include pentanol, hexanol, heptanol, octanol, 1-decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and 2,4-diethyl-1,5-pentanediol. Examples of 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. 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.

[0052] The easily volatile binder may be used alone or in combination of two or more.

[0053] As the readily volatile binder, terpene alcohols are preferred in terms of stability at room temperature, and among terpene alcohols, isobornylcyclohexanol is more preferred.

[0054] Isobornylcyclohexanol is also known as 4-[1,7,7-trimethylbicyclo[2.2.1]heptan-2-yl]cyclohexanol. Its boiling point is between 308°C and 318°C. Its vapor pressure is 0.00003 mmHg at 25°C. Isobornylcyclohexanol has the following characteristic physical properties. Specifically, when isobornylcyclohexanol is heated from room temperature (23±2°C) to 600°C at a rate of 10°C / min under a nitrogen gas flow of 200 mL / min, it undergoes a significant mass loss above 100°C and evaporates at 245°C (no further mass loss is observed). Furthermore, while it exhibits an extremely high viscosity of 1,000,000 mPa·s at 25°C, it exhibits a relatively low viscosity of 1,000 mPa·s or less at 60°C. The mass loss is calculated assuming that the mass loss rate at the measurement starting temperature (room temperature) is 0%. As described above, isobornylcyclohexanol exhibits extremely high viscosity at 25°C, making it easy for the sintered bonding layer 2 to maintain its sheet shape at room temperature. On the other hand, isobornylcyclohexanol exhibits relatively low viscosity at 60°C, making it tacky. That is, the sintered bonding layer 2 containing isobornylcyclohexanol can adequately maintain its sheet shape at room temperature and can become tacky at temperatures of 60°C or higher. The temperature when the semiconductor element is temporarily fixed to an adherend such as a substrate via the sintered bonding layer 2 is usually 60 to 80° C. At such a temperature, isobornylcyclohexanol becomes tacky for the above-mentioned reasons. Therefore, by including isobornylcyclohexanol as the second organic binder, the sintered bonding layer 2 has better temporary fixation properties to an adherend such as a substrate. In other words, after the semiconductor element is temporarily fixed to the adherend, it is possible to further prevent the semiconductor element from shifting from its mounting position or the sintered bonding layer 2 from lifting off the adherend.

[0055] The sintered bonding layer 2 may contain 1 mass % or more, 2 mass % or more, or 3 mass % or more of the organic binder. The sintered bonding layer 2 preferably contains 3 mass % or more, and more preferably 5 mass % or more of the organic binder. The sintered bonding layer 2 may contain 40 mass % or less, 35 mass % or less, or 30 mass % or less of the organic binder. The sintered bonding layer 2 preferably contains 20 mass % or less, more preferably 10 mass % or less of the organic binder.

[0056] When the sintered bonding layer 2 contains 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 and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 40% by mass or less. On the other hand, in the sintered bonding layer 2, the content of the second organic binder may be greater than the content of the first organic binder.

[0057] The sintered bonding layer 2 preferably contains 0.01 mass % or more of the first organic binder, more preferably 0.05 mass % or more, even more preferably 0.10 mass % or more, and even more preferably 0.20 mass % or more. The sintered bonding layer 2 preferably contains 20.0 mass % or less of the first organic binder, more preferably 10.0 mass % or less, even more preferably 7.5 mass % or less, and even more preferably 5.0 mass % or less.

[0058] The sintered bonding layer 2 preferably contains 0.5 mass % or more of the second organic binder, more preferably 1.0 mass % or more, even more preferably 1.5 mass % or more, and even more preferably 2.0 mass % or more. 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 even more preferably 10.0 mass % or less.

[0059] The sintered bonding layer 2 has, for example, a structure in which a plurality of layers are stacked. The sintered bonding layer 2 may have a single-layer structure in which a plurality of layers are integrated together, resulting in no interfaces between the plurality of layers.

[0060] In this embodiment, the thickness of the sintered bonding layer 2 is preferably 5 μm or more, and more preferably 10 μm or more. The thickness of the sintered bonding layer 2 may be 300 μm or less, 200 μm or less, or 100 μm or less. When the thickness of the sintered bonding layer 2 is within the above range, the volatilization or decomposition of the organic binder contained in the sintered bonding layer 2 is facilitated when the sinterable particles are sintered together by a sintering process to bond a semiconductor element such as the semiconductor chip B to a substrate (during the sintering process). As a result, voids are less likely to remain in the sintered bonding layer, and the performance reliability of the sintered bonding layer 2 is fully demonstrated.

[0061] The thickness of the sintered bonding layer 2 is calculated by measuring the thickness at five randomly selected locations using, for example, a dial gauge (manufactured by PEACOCK, model R-205) and arithmetically averaging these measured values.

[0062] [Base layer of sinter bonding sheet] In this embodiment, the substrate layer 1 of the sinter bonding sheet 10 functions as a support in the sinter bonding sheet 10. The substrate layer 1 is made of, for example, a plastic film. The substrate layer 1 may also function as a coating substrate onto which a varnish (described in detail later) for forming the sinter bonding layer 2 is applied. The substrate layer 1 may also be a general release liner.

[0063] Examples of materials for the plastic film include polyolefin resins, polyester resins such as polyethylene terephthalate resins, polyurethane resins, polycarbonate resins, polyether ether ketone resins, polyimide resins, polyetherimide resins, polyamide resins, wholly aromatic polyamide resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyphenyl sulfide resins, aramid resins, fluororesins, cellulose-based resins, and silicone resins. The base layer 1 may be made of one type of material, or two or more types of materials.

[0064] Examples of polyolefin resins include low-density polyethylene resins, linear low-density polyethylene resins, medium-density polyethylene resins, high-density polyethylene resins, very low-density polyethylene resins, random copolymer polypropylene resins, block copolymer polypropylene resins, homopolypropylene resins, polybutene resins, polymethylpentene resins, ethylene-vinyl acetate copolymer resins, ionomer resins, ethylene-butene copolymer resins, and ethylene-hexene copolymer resins. Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene terephthalate resin.

[0065] The base layer 1 may have a single-layer structure or a multi-layer structure. A single-layer structure is a structure formed from one type of material. For example, a base layer 1 formed by laminating two or more layers formed from one type of material has a single-layer structure. On the other hand, a base layer 1 formed by laminating two or more layers formed from different materials has a multi-layer structure.

[0066] When the base layer 1 is a plastic film, the base 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. Furthermore, the substrate layer 1 may be a release liner with a release-treated surface in contact with the sintered bonding layer 2. For example, a release agent may be applied to one surface of the substrate layer 1 in contact with the sintered bonding layer 2. In this case, when manufacturing a semiconductor device, the individualized sintered bonding layer 2 (individual sintered bonding layer piece 2") can be easily peeled from one surface of the substrate layer 1 (release liner).

[0067] The thickness of the base layer 1 is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. By making the thickness of the base layer 1 10 μm or more, for example, external forces (such as compressive forces or shear forces transmitted from conveying rolls) applied during the production of the sinter-bonding sheet 10 can be prevented from being transmitted to the sinter-bonding layer 2. This prevents such forces from causing parts of the sinter-bonding layer 2 to break or dents to form in parts of the sinter-bonding layer 2. This prevents a decrease in the yield of the sinter-bonding sheet 10 during production. The thickness of the base layer 1 is preferably 500 μm or less, and more preferably 200 μm or less. When the thickness of the base layer 1 is 500 μm or less, the base layer 1 can easily follow the sintered bonding layer 2 when the sinter bonding sheet 10 is rolled up, and therefore, the base layer 1 can be more effectively prevented from floating away from the sintered bonding layer 2. The thickness of the base layer 1 is measured in the same manner as the thickness of the sintered bonding layer 2 described above.

[0068] The surface of the base layer 1 that comes into contact with the sintered bonding layer 2 may have a surface roughness of, for example, 20 μm or less. The surface roughness of the base layer 1 is measured in the same manner as the surface roughness Ra of the sintered bonding layer 2 described above.

[0069] The sinter bonding sheet 10 may be in a rolled state. The sinter bonding sheet 10 includes a cylindrical roll core around which the sinter bonding sheet is rolled. Preferably, the diameter of the roll core is 30 mm or more and 260 mm or less. When the roll core diameter (roll diameter) is 30 mm or more, the curvature of the rolled sinter bonding sheet 10 does not become too large, which further prevents cracks in the sinter bonding layer 2. The roll core may be a solid columnar or a hollow columnar (cylindrical). In the latter case, the diameter of the cylindrical roll core refers to the outer diameter. When the sinter bonding sheet 10 is wound around a winding core having the above-mentioned diameter and in a wound state, a bending force is applied to the entire sinter bonding sheet 10 (particularly the portion close to the winding core). This makes it easy for delamination to occur between the base layer 1 and the sinter bonding layer 2, and the base layer 1 is likely to lift off from the sinter bonding layer 2. Even in this state, the surface roughness Ra of the surface of the sinter bonding layer 2 that contacts the base layer 1 is within the above-mentioned numerical range, so that the rolled sinter bonding sheet 10 of this embodiment prevents the base layer 1 from lifting off from the sinter bonding layer 2.

[0070] Next, a method for producing the above-mentioned sinter-bonding sheet will be described.

[0071] The method for producing the sinter-bonding sheet includes: a step of forming a plurality of intermediates of the sintered bonding layer into a sheet shape by volatilizing a solvent (e.g., an organic solvent) from a varnish containing the sinterable particles, the organic binder, and the solvent (hereinafter referred to as a sheet-shaped intermediate forming step); and a step of applying a press treatment to the sintered bonded layer produced by bonding the plurality of intermediate bodies together (hereinafter referred to as a press treatment step).

[0072] In the above-mentioned method for producing a sinter-bonding sheet, the sinter-bonding sheet may be produced continuously (hereinafter also referred to as a continuous production method). In the continuous production method, for example, a long sheet-like base material layer 1 (such as a release liner) is used. The base material layer is unwound from the wound base material layer 1 (a wound base material layer), and while the base material layer 1 is moved in one longitudinal direction, a sheet-like intermediate 2' is continuously formed on at least one side of the base material layer 1. When the sinter-bonding layer 2 is continuously formed, the solvent is evaporated from the varnish applied to the base material layer, and a sheet-like intermediate 2' is formed on the base material layer, thereby producing a laminate of the base material layer 1 and the sheet-like intermediate 2'. While this laminate is further moved in one direction, multiple intermediates 2' are bonded together, and then further subjected to a pressing process or the like. On the other hand, in the above-mentioned method for manufacturing a sheet for sinter bonding, flat sheets for sinter bonding may be manufactured one by one (hereinafter also referred to as a sheet-based manufacturing method). In the sheet-based manufacturing method, for example, a rectangular sheet-shaped substrate layer 1 (such as a release liner) is used. A sheet-shaped intermediate 2' is formed on at least one side of the substrate layer 1, and a laminate of the substrate layer 1 and the sheet-shaped intermediate 2' is produced. For example, two laminates are prepared and arranged so that the intermediates 2' overlap each other, and the overlapped intermediates 2' are subjected to a press treatment or the like.

[0073] In the above-mentioned method for producing a sheet for sinter bonding, a plurality of (two or more) sheet-like intermediates may be laminated together. Hereinafter, an example of a method for producing a sheet for sinter bonding by a continuous process by laminating a plurality of (two) sheet-like intermediates together will be described in detail. The production equipment for carrying out the continuous production method and each step in the continuous production method will be described below.

[0074] 2A, the manufacturing equipment 100 for carrying out the continuous manufacturing method includes a first device for producing a sheet-like intermediate 2' of a sintered bonding layer. The first device includes a roll P on which a long substrate layer 1 (such as a release liner) is rolled, a coating unit T that coats one side of the long substrate layer 1 supplied from the roll P with the varnish supplied from a tank, a drying unit U that volatilizes the solvent from the coated varnish, another roll Q on which a long protective sheet J (such as a release liner) is rolled, a covering unit V that covers the sheet-like intermediate 2' on the substrate layer 1 unwound from the drying unit U with the long protective sheet J supplied from the roll Q, and a roll R that rolls a laminate in which the sheet-like intermediate 2' is disposed between the substrate layer 1 and the protective sheet J. In the continuous manufacturing method, a long substrate layer 1 (such as a release liner) is wound around a roll P, and the substrate layer 1 is continuously unwound in one longitudinal direction. A varnish supplied from a tank is coated in a coating section T onto one side of the substrate layer 1 supplied from the roll P. The solvent is evaporated from the layered varnish in a drying section U. The evaporation is carried out by heating, reducing pressure, or the like. Furthermore, a sheet-like intermediate 2' formed on the substrate layer 1 after the solvent has evaporated is covered in a covering section V with a protective sheet J supplied from another roll Q. A roll R of a laminate is then obtained, in which the substrate layer 1 and the protective sheet J are respectively arranged on both sides of the sheet-like intermediate 2'. At this stage, the sheet-like intermediate 2' has not been subjected to a press treatment, and therefore the surface of the sheet-like intermediate 2' does not have the predetermined surface roughness described above.

[0075] Furthermore, the manufacturing equipment 100 for carrying out the continuous manufacturing method includes a second device for bonding two sheet-like sintered bonding layer intermediates 2', as shown in FIG. 2B. The second device includes two of the above-mentioned wound bodies R. The above-mentioned protective sheet J is used to prevent foreign matter from adhering to the surface of the sheet-like intermediate body 2' when the wound body R is transferred from the first device to the second device. The second device also includes a press processing section S that bonds together two sheet-like intermediate bodies 2′ supplied from two rolls R, respectively, and performs a press process. The second device also includes a winding section W that winds up the sinter bonding sheet 10 having the sinter bonding layer formed by the press process. In the continuous manufacturing method, the protective sheet J of each laminate is removed as the laminate is unwound from each of the two rolls R. The exposed surfaces of the sheet-like intermediate bodies 2' exposed after the protective sheet J has been removed are bonded together, and the laminate in which the two bonded intermediate bodies 2' are sandwiched between the two base layers 1,1 is sent to a press processing section S. The press processing section S presses the two bonded intermediate bodies 2' to form a sinter bonding layer 2, and the press-treated sinter bonding sheet 10 is wound up in a winding section W.

[0076] In the above example, the manufacturing equipment for carrying out the continuous manufacturing method includes a first device and a second device, and is configured to once wind up a laminate having a sheet-like intermediate 2'. On the other hand, the manufacturing equipment for carrying out the continuous manufacturing method may also include a device that bonds the long sheet-like intermediates 2' of the sintered bonding layer produced on one side of the base layer 1 to each other without covering them with a protective sheet, and further presses them, and is configured to carry out all steps continuously.

[0077] The varnish used in the continuous manufacturing method is prepared, for example, by mixing the above-mentioned sinterable particles, the above-mentioned organic binder, and an organic solvent, dispersing the sinterable particles in the organic solvent, and dissolving the organic binder in the organic solvent.

[0078] As the organic solvent, for example, alcohols such as ethanol, or ketones such as methyl ethyl ketone (MEK) can be used.

[0079] The mixing temperature when preparing the varnish is not particularly limited, and is, for example, from 5° C. to 70° C. The mixing method is not particularly limited, and a mixing method using a general stirring device can be used.

[0080] The solid content of the varnish is preferably 60% by mass or less, more preferably 58% by mass or less, and even more preferably 55% by mass or less. The solid content is the component excluding the organic solvent, for example, the total content of the sinterable particles and the organic binder. 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.

[0081] 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. Such viscosity is measured using an E-type viscometer (for example, the RE-85 model, manufactured by Toki Sangyo Co., Ltd.). Specifically, the viscosity is measured using a 1°34' x R24 cone rotor as a jig, with a measurement sample volume of 1.1 mL and a rotation speed of 1.0 rpm.

[0082] In the continuous production method, in the sheet-like intermediate formation step, for example, the varnish is applied to a predetermined thickness on the substrate layer 1 to form a coating film, followed by volatilizing the organic solvent from the coating film.

[0083] The varnish can be applied using a common coating device, such as die coating, gravure coating, reverse coater coating, or blade coating.

[0084] The organic solvent may be evaporated by heating or by reducing pressure. When the organic solvent is evaporated by heating, for example, the heat treatment can be carried out at a temperature of 100°C or higher and 150°C or lower for 1 minute or longer and 10 minutes or shorter.

[0085] In the continuous manufacturing method, the pressing step involves, for example, applying a pressure of 0.1 MPa to 10.0 MPa at a temperature of 30°C to 150°C with the base layer in contact with one or both surfaces of the sintered bonding layer made from the plurality of intermediate bodies 2'. This pressure refers to the pressure applied to the sintered bonding layer. The press processing section S is configured to include, for example, two pressure rollers, and by sandwiching the two base material layers 1 and the two intermediate bodies 2' between the two pressure rollers and rotating the two pressure rollers in opposite directions, the base material layers 1, 1 and the intermediate bodies 2', 2' are fed in one direction while being pressurized. The press processing section S is also configured to perform the above pressurization in a predetermined temperature environment. In this way, the press processing section S is configured to perform the press processing within a predetermined temperature range and a predetermined pressure range.

[0086] In the above pressing treatment, the temperature is preferably 70° C. or higher and 100° C. or lower, and the pressure is preferably 0.5 MPa or higher and 3.0 MPa or lower. In the above pressing process, the speed at which the base layer and the sintered bonding layer are fed in one direction is, for example, 0.1 m / min or more and 3.0 m / min or less, and preferably 0.5 m / min or more and 2.5 m / min or less.

[0087] The sinter-bonding sheet 10 wound by the winding unit W after the above pressing process can be stored in a wound state. Alternatively, the wound sinter-bonding sheet 10 may be unwound, formed into a flat sheet, and then cut to a desired size. A plurality of cut flat sheets of sinter-bonding sheet 10 may be stored in a stacked state.

[0088] On the other hand, in contrast to the continuous manufacturing method, the single-wafer manufacturing method can use manufacturing equipment equipped with a flat plate press for pressing. The flat plate press has, for example, two compression flat plate members K, K. In the single-wafer manufacturing method, for example, as shown in Figure 2C, (I) A varnish prepared in the same manner as above is applied to one side of the base layer 1 (e.g., a release liner), and the solvent is evaporated to form a sheet-like intermediate 2' (intermediate for the sintered bonding layer) on one side of the base layer 1. This produces a laminate sheet of the base layer 1 and the sheet-like intermediate 2'. The two laminate sheets thus produced are then superimposed on each other so that the sheet-like intermediates 2' are in contact with each other. (II) The two stacked laminated sheets are pressed using a flat press. Specifically, the two laminated sheets are placed between the two compression flat plate members K, K, and the distance between the two compression flat plate members K, K is reduced. The temperature and pressure used in the press treatment in the single-wafer manufacturing method can be the same as those used in the press treatment in the continuous manufacturing method described above. (III) A sheet for sinter bonding can be obtained in which the base layers 1, 1 are disposed on both sides of the sinter bonding layer 2, respectively.

[0089] In the above description, a specific example in which two sheet-like intermediate bodies 2' are bonded together to produce the sintered bonding layer 2 has been described in detail, but three or more sheet-like intermediate bodies 2' may be bonded together to produce the sintered bonding layer 2. In this case, after bonding two sheet-like intermediate bodies 2' together as described above, another sheet-like intermediate body 2' is bonded to produce the sintered bonding layer 2.

[0090] [Method of using sinter bonding sheet (semiconductor device manufacturing method)] The sinter bonding sheet 10 manufactured as described above can be used as a component for manufacturing a semiconductor device, for example. Next, an example of a method for manufacturing a semiconductor device using the sinter bonding sheet 10 according to this embodiment will be described with reference to the drawings.

[0091] The above-mentioned method for manufacturing a semiconductor device is carried out, for example, using a plurality of semiconductor chips B, a substrate having a plurality of mounting areas on which the plurality of semiconductor chips B are mounted, the above-mentioned sintering bonding sheet 10, and a pressing member used to temporarily fix each of the plurality of semiconductor chips B to the plurality of mounting areas.

[0092] The following description will be given taking as an example a case where a semiconductor chip B is mounted on a substrate such as a DBC (Direct Bonded Copper) substrate or an AMB (Active Metal Brazing) substrate using a collet A as a pressing member. These substrates have, for example, a copper die pad E and a copper thin layer F on each side of a ceramic insulating layer D. The copper die pad E is the mounting area for the semiconductor chip B.

[0093] First, a semiconductor wafer is cut on a dicing tape C to obtain a plurality of semiconductor chips B from the semiconductor wafer (see FIG. 3A). In other words, the semiconductor wafer is divided into a plurality of pieces to obtain the semiconductor chips B. A commercially available product can be used as the dicing tape C.

[0094] The resulting semiconductor chip B has, for example, a rectangular thin plate shape. 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. The area of ​​the semiconductor chip B when viewed from one side in the thickness direction is, for example, 0.01 mm 2 More than 1000mm 2 Such an area is 0.04 mm 2 Over 500mm 2 It is preferable that:

[0095] Next, as shown in FIG. 3B, the sinter bonding sheet 10 is placed on the first stage G so that the sinter bonding layer 2 is above the base layer 1. Then, one semiconductor chip B is pressed against the sintered bonding layer 2 with the collet A, thereby adhering the semiconductor chip B to a part of the sintered bonding layer 2. The pressure during pressing is preferably 0.01 MPa or more and 10 MPa or less, and more preferably 0.1 MPa or more and 5 MPa or less. Furthermore, the temperature of the collet A or the first stage G during pressing is preferably 40°C or more and 150°C or less, and more preferably 50°C or more and 130°C or less. When the pressure when pressing the semiconductor chip B against the sintered bonding layer 2 is within the above range, or when the temperature of the collet A or the first stage G is within the above range, when the collet A is lifted, a semiconductor chip B having an individual piece 2" of the sintered bonding layer attached thereto can be suitably obtained, as will be described below. The shape and size of the surface of the collet A that comes into contact with the semiconductor chip B are substantially the same as the shape and size of one semiconductor chip B.

[0096] Next, the collet A is lifted as shown in FIG. 3C. At this time, a portion of the sintered bonding layer 2 attached to the semiconductor chip B is lifted together with the semiconductor chip B. In other words, the semiconductor chip B is lifted by the collet A while the individual pieces 2" of the sintered bonding layer remain attached. This results in a semiconductor chip B attached with the individualized sintered bonding layer 2 (hereinafter also referred to as the individual pieces 2" of the sintered bonding layer). At this time, since the surface roughness Ra of the surface where the sintered bonding layer piece 2" is in contact with the base layer 1 is 10.5 nm or more and 90.0 nm or less as described above, the sintered bonding layer piece 2" peels off from one side of the base layer 1 and is easily lifted up together with the semiconductor chip B. In other words, good transferability is exhibited.

[0097] Next, the substrate (ceramic insulating layer D, copper die pad E, and copper thin layer F) is placed on a second stage H (see FIG. 3D). Then, as shown in FIG. 3D, while holding collet A at any temperature within the range of 25°C or higher and 150°C or lower, collet A is lowered vertically to bring the piece 2″ of the sintered bonding layer attached to semiconductor chip B into contact with copper die pad E. Next, collet A presses (presses) semiconductor chip B downward toward copper die pad E. As a result, the semiconductor chip B is temporarily fixed to the copper die pad E via the sintered bonding layer piece 2'' (see FIG. 3D). The pressure when pressing the semiconductor chip B against the copper die pad E is preferably 0.01 MPa or more and 50 MPa or less, and more preferably 0.1 MPa or more and 30 MPa or less.

[0098] The substrate serving as the adherend for the individual pieces 2" of the sintered bonding layer may be a lead frame. A general lead frame can be used as the lead frame. For example, a lead frame in which a Cu frame has been Ag-plated, or a lead frame in which a Cu frame has been plated with Ni, Pd, and Au in that order (Palladium Pre-Plated Lead Frame, Pd-PPF) can be used.

[0099] After carrying out the above-mentioned operations to temporarily fix one semiconductor chip B to the copper die pad E, the same operations are repeated. More specifically, as shown in FIG. 4A, a collet A separates another semiconductor chip B from the dicing tape C and lifts it up. Next, similarly to FIG. 3B, another semiconductor chip B is pressed against the sinter bonding layer 2 of the sinter bonding sheet 10 with a collet A. Furthermore, similarly to FIG. 3C, the collet A is pulled up, and the semiconductor chip B with the sintered bonding layer piece 2'' attached thereto is separated from the base material layer 1 and lifted up. Next, while the collet A is maintained at the same temperature as above, the semiconductor chip B with the sintered bonding layer piece 2'' attached thereto is brought into contact with another mounting area of ​​the copper die pad E. Then, as shown in FIG. 4B, the collet A presses (presses) the semiconductor chip B downward toward the copper die pad E. As a result, the semiconductor chip B is temporarily fixed to another mounting area of ​​the copper die pad E via the piece 2'' of the sintered bonding layer (see FIG. 4B). The above operations are repeated in order until all the semiconductor chips B to be temporarily fixed to the copper die pad E are placed on the copper die pad E.

[0100] When temporarily fixing each semiconductor chip B, the collet A may be heated to a temperature at which the sinterable particles contained in the pieces 2" of the sintered bonding layer can be sintered. This may allow a primary sintering process to be carried out on the sinterable particles contained in the pieces 2" of the sintered bonding layer. In other words, immediately after temporary fixing as described above, part of the sintering process may be carried out on the pieces 2" of the sintered bonding layer.

[0101] If the sinterable particles contained in the sintered bonding layer piece 2" can be sintered at a heating temperature of 400°C or less, it is preferable to heat the collet A to a temperature of 200°C or more. By heating the collet A to 200°C or more, the sinterable particles can be more thoroughly sintered together. Therefore, the semiconductor chip B can be more firmly bonded to the copper die pad E via the sintered bonding layer piece 2". In other words, the bonding reliability of the semiconductor chip B to the substrate is further improved.

[0102] When carrying out the primary sintering process, it is preferable to rapidly (in about 5 seconds) heat up the collet A. The temperature of the collet A is preferably raised at 30°C / sec or more, and more preferably at 45°C / sec or more.

[0103] The primary sintering process may be performed not only by heating the collet A, but also by heating the second stage H at the same temperature as above. This heats the pieces 2" of the sintered bonding layer from both sides in the thickness direction, allowing the sinterable particles to be sintered together more thoroughly. This allows the semiconductor chip B to be more fully bonded to the copper die pad E via the pieces 2" of the sintered bonding layer. In other words, the bonding reliability of the semiconductor chip B to the substrate is further improved.

[0104] The temperature of the heated second stage H is preferably equal to or lower than the temperature that suppresses oxidation of the copper die pad E or the thin copper layer F. The heating temperature of the second stage H is preferably 150° C. or lower.

[0105] When performing the primary sintering process as described above, for example, after the primary sintering process, collet A may be lifted to separate semiconductor chip B from collet A, thereby lowering the temperature of collet A to a temperature (e.g., 50°C) at which the sinterable particles become less likely to sinter. When the primary sintering process is performed on each of the individual pieces 2" of all the sintered bonding layers, bonding wires may be bonded to required locations after all the semiconductor chips B have been bonded.

[0106] In the method for manufacturing a semiconductor device, after temporarily fixing multiple semiconductor chips B to a substrate, a heating process may be performed in which the individual pieces 2" of the sintered bonding layer are heated to a temperature at which the sinterable particles can be sintered.In the heating process, heating may be performed while applying a compressive force in the thickness direction to at least one of the multiple individual pieces 2" of the sintered bonding layer. When the above-mentioned primary sintering process is performed, the above-mentioned heating step corresponds to the secondary sintering process. In other words, the sintering process can be performed by both the above-mentioned primary sintering process and the secondary sintering process (the above-mentioned heating step).

[0107] More specifically, in the method for manufacturing a semiconductor device, the sintering process can be carried out as follows. In the heating step of the sintering process, for example, at least one of the multiple sintered bonding layer pieces 2" is heated while being pressed in the thickness direction. Specifically, after the semiconductor chip B is temporarily fixed, a heating and pressurizing device such as that shown in Figure 5A, which is configured to be capable of heating, may be used to heat the sintered bonding layer piece 2" while applying a compressive force in the thickness direction. For example, the heating and pressing device includes two flat plates Z, Z. The two flat plates Z, Z are arranged to sandwich the second stage H, the substrate (ceramic insulating layer D, copper die pad E, and thin copper layer F), and the plurality of semiconductor chips B temporarily fixed to the copper die pad E via the sintered bonding layer pieces 2" therebetween. The distance between the two heated flat plates is then reduced and pressure (compression) is applied to the above-mentioned plurality of components, thereby heating the sintered bonding layer pieces 2" while pressing them. Note that a buffer material (e.g., made of PTFE with a thickness of 10 μm to 2 mm) may be placed between the plurality of semiconductor chips B and one of the flat plates Z to absorb the pressing force and prevent the semiconductor chips B and the sintered bonding layer pieces 2" from tilting due to the pressing force. By carrying out the heating process in this manner, the pieces 2" of the sintered bonding layer can be heated while being pressed together, so that the semiconductor chip B can be firmly bonded to the substrate (copper die pad E) via the pieces 2" of the sintered bonding layer. This improves the bonding reliability of the semiconductor chip B to the substrate. After the heating step is performed in this manner, bonding wires may be bonded to required locations. A jig or the like for arranging a plurality of substrates may be placed between the lower flat plate Z and the copper die pad E shown in FIG. 5A.

[0108] On the other hand, in the heating process, as shown in Figure 5B, after all of the semiconductor chips B to be bonded have been temporarily fixed, the second stage H may be heated without applying a compressive force in the thickness direction to the pieces 2" of the sintered bonding layer.At this time, the second stage H is heated to a temperature at which the sinterable particles contained in the pieces 2" of the sintered bonding layer can be sintered (for example, any temperature in the range of 200°C or higher and 400°C or lower). Even when such a heating process is performed, the semiconductor chip B can be firmly bonded to the substrate (copper die pad E) via the individual pieces 2'' of the sintered bonding layer.Therefore, the bonding reliability of the semiconductor chip B to the substrate can be improved. By carrying out the heating step as described above, a heating and pressurizing device for applying a compressive force to the individual pieces 2 ″ of the sintered bonding layer is not required, and therefore the manufacturing device can be made simpler.

[0109] In the above-described method for manufacturing a semiconductor device, further steps may be carried out. For example, a wire bonding step may be carried out to electrically connect a part of the semiconductor chip B to a part of the substrate. In addition, a sealing process may be carried out in which the semiconductor chip B and the individual pieces 2" of the sintered bonding layer are sealed with a thermosetting resin such as an epoxy resin. In the sealing process, a heat treatment is carried out at a temperature of, for example, 150°C or higher and 200°C or lower in order to promote the curing reaction of the thermosetting resin.

[0110] In the method for manufacturing a semiconductor device, as described above, for example, a sintering process is performed in which a compressive force is applied to the piece 2" of the sintered bonding layer in the thickness direction while heating the piece 2" to bond the piece 2" of the sintered bonding layer to the substrate.

[0111] The sinter-bonding sheet and the manufacturing method thereof according to this embodiment are as exemplified above, but the present invention is not limited to the sinter-bonding sheet and the manufacturing method thereof exemplified above. That is, various forms used in general sinter-bonding sheets and the like can be adopted within the scope that does not impair the effects of the present invention.

[0112] The matters disclosed by this specification include the following. (1) a sintered bonding layer including sinterable particles containing a conductive metal and an organic binder; a base layer overlapping at least one surface of the sintered bonding layer, A sinter bonding sheet, wherein the surface of the sinter bonding layer overlapping the base layer has a surface roughness Ra of 10.5 nm or more and 90.0 nm or less. (2) The sheet for sinter bonding according to (1) above, wherein the average particle size of the sinterable particles is 0.01 μm or more and 10 μm or less. (3) The sinter bonding sheet according to (1) or (2) above, wherein the sinter bonding layer contains the sinterable particles in an amount of 80% by mass or more and 99% by mass or less. (4) The sinter-bonding sheet according to any one of (1) to (3), wherein the sinter-bonding layer has a thickness of 10 μm or more and 300 μm or less. (5) The sinter bonding sheet according to any one of (1) to (4), wherein the thickness of the substrate layer is 10 μm or more and 200 μm or less. (6) The sinter-bonding sheet according to any one of (1) to (5), which is in a rolled state. (7) The sheet for sinter bonding according to (6) above, which comprises a cylindrical core around which the sheet for sinter bonding is wound, the core having a diameter of 30 mm or more and 260 mm or less. (8) A method for producing a sheet for sinter bonding, comprising: a sinter bonding layer including sinterable particles containing a conductive metal and an organic binder; and a base material layer overlapping at least one surface of the sinter bonding layer, forming a plurality of intermediate bodies of the sintered bonding layer into a sheet shape by volatilizing the solvent from a varnish containing the sinterable particles, the organic binder, and a solvent; and applying a press treatment to the sintered bonding layer produced by bonding the plurality of intermediate bodies together, A method for manufacturing a sheet for sinter bonding, wherein the press treatment involves contacting the base material layer with at least one of the surfaces of the sinter bonding layer and applying a pressure of 0.1 MPa or more and 10.0 MPa or less at a temperature of 30°C or more and 150°C or less. [Example]

[0113] Next, the present invention will be explained in more detail by way of experimental examples. However, the following examples are intended to explain the present invention in more detail and are not intended to limit the scope of the present invention.

[0114] (raw material for sintered bonding layer) [Sinterable particles] Silver particles (a mixture of the first and second silver particles shown below, mass ratio = 9 / 1) First silver particles (average particle diameter 60 nm, manufactured by DOWA Electronics Co., Ltd.) Secondary silver particles (average particle diameter 1100 nm, manufactured by Mitsui Mining & Smelting Co., Ltd.) [Organic binder] First organic binder (thermolybdenum polymer binder): Polycarbonate resin: Product name: "QPAC40" manufactured by Empower Materials Second organic binder (easily volatile binder): Isobornylcyclohexanol Product name: Tersolv MTPH, manufactured by Nippon Terpene Chemical Industry Co., Ltd. (base material layer) Release-treated film (product name "Diafoil MRA38", manufactured by Mitsubishi Chemical Corporation) 38 μm thick

[0115] Example 1 A varnish was prepared by dissolving or suspending the first silver particles, the second silver particles, the first organic binder (polycarbonate resin), and the second organic binder (isobornylcyclohexanol) in an organic solvent according to the formulation shown in Tables 1 and 2. Specifically, a hybrid mixer (model "HM-500", manufactured by Keyence Corporation) was used to stir the mixture for 3 minutes in stirring mode. Next, varnish was applied to the release-treated surface of the base layer, and then heated at 110°C for 3 minutes to form a sheet-like intermediate for the sintered bonding layer on the base layer. In this way, a laminate sheet (a laminate sheet with an intermediate) was produced. Next, two laminate sheets (two laminate sheets with intermediates) were supplied from two rolls, and the two laminate sheets were stacked so that the sheet-like intermediates were bonded together, and a press treatment was carried out under the conditions shown in Table 3. The sheet was then wound up with a winding force of 70 N or less to produce a wound sheet for sinter bonding having a sinter bonding layer with a thickness of 50 μm. The diameter of the winding core was 203 mm. In Table 1, the blending amount of sinterable particles is shown as the amount at the time of charging, and in Table 2, the blending amount of sinterable particles is shown as the ash content value.

[0116] [Table 1]

[0117] [Table 2]

[0118] [Table 3]

[0119] (Examples 2 and 3) Each sinter-bonding sheet was produced in the same manner as above, except that the composition and physical properties were changed as shown in Table 3. In Example 3, two of the above-mentioned flat laminated sheets were stacked on top of each other, and the two laminated sheets in this state were pressed using a flat press. The sinter-bonding sheet thus produced was not rolled, but remained in the flat sheet form.

[0120] (Comparative Examples 1 to 3) Each sinter-bonding sheet was produced in the same manner as above, except that the composition and physical properties were changed as shown in Table 3. In Comparative Example 3, two laminated sheets were not stacked together (bonding of sheet-like intermediate bodies), and no pressing treatment was performed.

[0121] Table 3 shows the configuration and physical properties of the sinter bonding layer of the sinter bonding sheet in each example and comparative example.

[0122] <Surface roughness Ra of sinter bonding sheet (sinter bonding layer)> The surface roughness Ra of the sinter bonding layer of each of the sinter bonding sheets manufactured as described above was measured by the method described above. The reference length (L) during measurement was 2.5 μm. The surface roughness Ra was measured on the surface overlapping the base layer. In each of the above examples and comparative examples, both surfaces of the sintered bonding layer overlapped the base layer, so the surface roughness of both surfaces of the sintered bonding layer was measured. As a result, both surfaces had the same surface roughness Ra.

[0123] <Evaluation of transferability of sintered bonding layer> The sheets for sinter bonding according to each example were evaluated for transferability of the sinter bonding layer to the Si chip. The evaluation test was carried out as follows. (1) A cushioning material (Yamauchi Corporation's "FF10N") was placed on the stage of a flip chip bonder "FC3000W" manufactured by Toray Engineering Co., Ltd. For each sinter bonding sheet of each example, one of the substrate layers (release liner / release-treated film) was peeled off, and the sheet was placed on the cushioning material with the exposed sinter bonding layer facing up. (2) A Si chip (5 mm square, 200 μm thick) with one entire side plated with silver was prepared. A collet heated to 100°C was used to press the Si chip's surface against the sintered bonding layer on the substrate layer, and a load of 1 MPa (25 N) was applied for 1 second. The Si chip was then lifted by the collet at a speed of 0.3 mm / s, separating the individual pieces of the sintered bonding layer from the substrate layer. (3) The size of the individual pieces of the sintered bonding layer that were separated (transferred) was observed under a microscope. (4) The above steps (1) to (3) were repeated three times, and the transferability was evaluated according to the following criteria. Excellent (〇): In all three cases, the sintered bonding layer was the same size as the Si chip and was lifted (transferred) without any wrinkles on the sintered bonding layer. Good (△): In one of the three cases, the sintered bonding layer was transferred to the same size as the Si chip, but wrinkles were observed in part of the sintered bonding layer. Poor (×): In any of the three cases, wrinkles occurred in multiple places on the sintered bonded layer, making it unsuitable for practical use. In order to achieve good transferability, the surface of the sintered bonding layer that is in contact with the base layer when lifting the Si chip as described above only needs to have a specific surface roughness. In other words, it is not necessary for both surfaces of the sintered bonding layer to have a specific surface roughness.

[0124] <Lifting of the base layer when wound (peeling between the base layer and the sintered bonding layer)> A sinter-bonding sheet having a thickness of 126 μm and a width of 120 mm was prepared with the same composition as each of the above examples or comparative examples. The sinter-bonding sheet had a 50 μm thick sinter-bonding layer, and the substrate layers (PET films) arranged on both sides of the sinter-bonding layer each had a thickness of 38 μm. Each sinter-bonding sheet was wound around a cylindrical core (made of ABS resin, outer diameter 8 inches) for two turns (1300 mm) at room temperature (23°C) to prepare a wound body. 24 hours after the wound body was prepared, the lifting of the substrate layer was evaluated according to the following evaluation criteria. The wound state of the sinter-bonding sheet makes it easy for the substrate layer to lift from the sinter-bonding layer. No (◯): When the sinter bonding sheet was unwound by 300 mm from the roll, the base layer on the core side did not peel off (float) from the sinter bonding layer. Yes (×): When the sinter bonding sheet was unwound by 300 mm from the roll, the base layer on the core side peeled off (floated) from the sinter bonding layer. In order to prevent the above-mentioned lifting, it is sufficient that the surface of the sintered bonding layer in contact with the base layer has a specific surface roughness. In other words, it is not necessary that both surfaces of the sintered bonding layer have a specific surface roughness.

[0125] As can be seen from the above evaluation results, the sintering bonding layer of the sintering bonding sheet of the example had good transferability to the semiconductor chip and was able to suppress lifting of the base layer. In addition, the sintering bonding layer of the sintering bonding sheet of the example also had good thermal conductivity and electrical conductivity. On the other hand, the sinter bonding layer of the sinter bonding sheet of the comparative example did not have good transferability to the semiconductor chip. In the comparative example, where the surface roughness was too large, lifting of the base layer could not be suppressed. [Industrial Applicability]

[0126] The sinter-bonding sheet of the present invention is suitably used, for example, as an auxiliary tool when manufacturing semiconductor devices. [Explanation of symbols]

[0127] 10: Sintering bonding sheet, 1: substrate layer, 2: sintered bonding layer, A: Collet, B: Semiconductor chip, C: Dicing tape, D: Ceramic insulating layer, E: Copper die pad, F: Copper thin layer, G: First stage, H: Second stage.

Claims

1. a sintered bonding layer including sinterable particles containing a conductive metal and an organic binder; a base layer overlapping at least one surface of the sintered bonding layer, A sinter bonding sheet, wherein the surface of the sinter bonding layer overlapping the base layer has a surface roughness Ra of 10.5 nm or more and 90.0 nm or less.

2. 2. The sinter-bonding sheet according to claim 1, wherein the average particle size of the sinterable particles is 0.01 μm or more and 10 μm or less.

3. The sinter-bonding sheet according to claim 1 or 2, wherein the sinter-bonding layer contains 80% by mass or more and 99% by mass or less of the sinterable particles.

4. 3. The sinter-bonding sheet according to claim 1, wherein the sinter-bonding layer has a thickness of 10 μm or more and 300 μm or less.

5. 3. The sinter-bonding sheet according to claim 1, wherein the thickness of the substrate layer is 10 μm or more and 200 μm or less.

6. The sinter-bonding sheet according to claim 1 or 2, which is in a rolled state.

7. The sinter-bonding sheet according to claim 6, further comprising a cylindrical core around which the sinter-bonding sheet is wound, the core having a diameter of 30 mm or more and 260 mm or less.

8. A method for producing a sheet for sinter bonding, comprising: a sinter bonding layer including sinterable particles containing a conductive metal and an organic binder; and a base material layer overlapping at least one surface of the sinter bonding layer, forming a plurality of intermediate bodies of the sintered bonding layer into a sheet shape by volatilizing the solvent from a varnish containing the sinterable particles, the organic binder, and a solvent; and applying a press treatment to the sintered bonding layer produced by bonding the plurality of intermediate bodies together, In the press treatment, the base material layer is abutted against at least one surface of the sinter bonding layer, and a pressure of 0.1 MPa or more and 10.0 MPa or less is applied at a temperature of 30°C or more and 150°C or less.

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