Sheet for heat bonding and sheet for heat bonding with dicing tape

Abstract

To provide a sheet for heat bonding having an adhesive layer with a good dispersibility of an organic binder.SOLUTION: There is provided a sheet for heat bonding, comprising: a sintered precursor layer including a sinterable particle; and an adhesion layer overlapping with one surface of the sintered precursor layer. The adhesion layer includes an organic binder and a sinterable particle. A content of the sinterable particle in the adhesion layer is 5 vol % or more and 40 vol % or less. A particle size distribution of the sinterable particle included in the adhesion layer as measured by particle size distribution measurement has at least two peak vertices.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a heat bonding sheet used, for example, when manufacturing a semiconductor device, and a heat bonding sheet with dicing tape. [Background technology]

[0002] Conventionally, thermal bonding sheets used in the manufacture of semiconductor devices have been known. These thermal bonding sheets have at least a sintering precursor layer containing sinterable particles. The sintering precursor layer has pressure-sensitive adhesive properties due to the inclusion of, for example, an organic binder. For example, in the manufacture of a semiconductor device, the sintering precursor layer is disposed between one side of a substrate and a semiconductor element (such as a semiconductor chip) and sintered to bond the substrate and the semiconductor element. In the manufacture of a semiconductor device, for example, the following steps are performed.

[0003] (1) A sintering precursor layer is placed on the adhesive layer of a dicing tape, which is made by laminating a base layer and an adhesive layer, and then a semiconductor wafer is attached to the adhesive layer, and the sintering precursor layer and the semiconductor wafer are cut into small pieces. (2) Using a jig such as a collet, a small piece of the sintering precursor layer attached to one semiconductor element is peeled off from the adhesive layer, and the semiconductor element with the small piece of the sintering precursor layer attached is picked up. (3) One semiconductor element with the small piece of sintering precursor layer attached thereto is attached to one side 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 the small pieces of the sintering precursor layer adhered thereto are temporarily fixed in the semiconductor element mounting area of ​​the substrate, thereby obtaining an intermediate semiconductor device. (5) A sintering process is performed by heating the intermediate semiconductor device product at a temperature at which the sinterable particles in the sintering precursor layer can be sintered together, thereby sintering the sinterable particles together and removing at least a portion of the organic binder from the sintering precursor layer, thereby bonding multiple semiconductor elements to the semiconductor element mounting area of ​​the substrate. After the above-described steps, the semiconductor elements are fixed in the semiconductor element mounting area of ​​the substrate by the sintering of the sinterable particles contained in the sintering precursor layer. That is, the semiconductor elements are fixed in the semiconductor element mounting area of ​​the substrate via the pieces of the sintering precursor layer that have been sintered.

[0004] In addition, in the manufacture of semiconductor devices, instead of performing the above steps (1) and (2), it is also possible to perform the following steps: a step of attaching and fixing only a semiconductor wafer onto the adhesive layer of a dicing tape, and then dicing only the semiconductor wafer to separate it into multiple semiconductor elements; a step of peeling and lifting one semiconductor element from the adhesive layer using a jig such as a collet, and then pressing the one semiconductor element onto the sintering precursor layer of the heat bonding sheet; a step of using this pressing force to separate a portion of the sintering precursor layer into small pieces corresponding to the size of the semiconductor element, while at the same time adhering the small pieces of the sintering precursor layer to the semiconductor element; and a step of lifting up the jig such as a collet to pick up one semiconductor element to which the small pieces of the sintering precursor layer are adhered.

[0005] Known examples of heat-bonding sheets that can be used in the manufacturing method of semiconductor devices described above include sheets that include a sintering precursor layer that becomes a strong sintered layer after sintering processing and an adhesive layer that is bonded to a semiconductor wafer or the like (e.g., Patent Document 1).

[0006] More specifically, in the heat bonding sheet described in Patent Document 1, the sintering precursor layer contains metal fine particles and an organic binder, and the adhesive layer contains, for example, metal fine particles and an organic binder. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-037548 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the adhesion layer described in Patent Document 1, the dispersibility of the organic binder may not always be good. If the dispersibility of the organic binder in the adhesion layer is not good, for example, when the sintering precursor layer and the semiconductor wafer are diced on a dicing tape, delamination may occur between the semiconductor wafer and the sintering precursor layer. More specifically, delamination may occur between the two adherends (the sintering precursor layer and the semiconductor wafer) attached to both sides of the adhesion layer.

[0009] However, it cannot be said that sufficient research has been conducted on a heat bonding sheet having an adhesive layer with good dispersibility of an organic binder.

[0010] Therefore, an object of the present invention is to provide a heat bonding sheet having an adhesive layer in which the organic binder has good dispersibility. [Means for solving the problem]

[0011] In order to solve the above problems, the heat bonding sheet according to the present invention has the following features: a sintering precursor layer containing sinterable particles and an adhesion layer overlying one surface of the sintering precursor layer, the adhesion layer includes an organic binder and sinterable particles, and the content of the sinterable particles in the adhesion layer is 5% by volume or more and 40% by volume or less; When the particle size distribution of the sinterable particles contained in the adhesion layer is measured, the particle size distribution has at least two peaks.

[0012] The heat bonding sheet with dicing tape according to the present invention comprises the heat bonding sheet described above and a dicing tape superimposed on one surface of the heat bonding sheet. [Effects of the Invention]

[0013] In the heat bonding sheet according to the present invention, the organic binder has good dispersibility in the adhesive layer. [Brief explanation of the drawings]

[0014] [Figure 1A] 2 is a schematic cross-sectional view of the heat bonding sheet of the present embodiment cut in the thickness direction. FIG. [Figure 1B] 2 is a schematic cross-sectional view of the heat bonding sheet with dicing tape of the present embodiment cut in the thickness direction. FIG. [Figure 2A] 1 is a schematic cross-sectional view showing a semiconductor wafer superimposed on a heat bonding sheet with dicing tape. [Figure 2B] 3 is a schematic cross-sectional view showing an example of how a semiconductor wafer and a heat bonding sheet are cut into small pieces. FIG. [Figure 2C] 10 is a schematic cross-sectional view showing how the semiconductor chip and the small piece of the thermal bonding sheet are lifted from the dicing tape by the collet. FIG. [Figure 2D] 10 is a schematic cross-sectional view showing a state in which a weakened region is formed inside a semiconductor wafer superimposed on a heat bonding sheet with dicing tape. FIG. [Figure 2E] 10 is a schematic cross-sectional view showing another example of how the semiconductor wafer and the heat bonding sheet are cut into small pieces. FIG. [Figure 3A] 10 is a schematic cross-sectional view showing a semiconductor chip with a small piece of heat-bonding sheet attached thereto being temporarily fixed to a substrate. [Figure 3B] 10 is a schematic cross-sectional view showing a state in which a further semiconductor chip with a small piece of heat-bonding sheet attached thereto is temporarily fixed to a substrate. [Figure 3C] FIG. 10 is a schematic cross-sectional view showing an example of how a small piece of a thermal bonding sheet is heated while being pressed. [Figure 4] 1 is a graph showing a specific example of a particle size distribution chart obtained by measuring the particle size distribution of sinterable particles contained in an adhesive layer. [Figure 5] Photographs showing examples of ultrasonic flaw detection images of thermal bonding sheets. DETAILED DESCRIPTION OF THE INVENTION

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

[0016] The heat bonding sheet 10 according to this embodiment comprises a sintering precursor layer 2 containing sinterable particles, and an adhesion layer 1 containing sinterable particles and overlapping one side of the sintering precursor layer 2, as shown in FIG. 1A, for example. The heat bonding sheet 10 according to this embodiment may further include a component migration preventing layer 3 containing at least a resin, as shown in Fig. 1A. Such component migration preventing layer 3 is used, for example, by being overlaid on a pressure-sensitive adhesive layer 22 of a dicing tape 20 (see Fig. 1B), which will be described in detail later.

[0017] The sheet for heat bonding 10 of this embodiment is, for example, in the form of a long strip. The sheet for heat bonding 10 of this embodiment may be stored in a state where it is rolled up into a cylindrical shape.

[0018] First, the sintering precursor layer 2, which is the main layer of the heat bonding sheet 10 of this embodiment, will be described in detail.

[0019] [Sintering precursor layer of heat bonding sheet] The sintering precursor layer 2 contains at least sinterable particles, and preferably further contains an organic binder. The sintering precursor layer 2 contains an organic binder and thus has pressure-sensitive adhesive properties, so that the sintering precursor layer 2 can be temporarily adhered to an adherend when subjected to a pressing force. Furthermore, when the sintering precursor layer 2 is subjected to a sintering process, the sinterable particles inside are sintered to each other. For example, the sintering precursor layer 2 can be disposed between a substrate and a semiconductor chip X and sintered to bond the two together. When the sintering precursor layer 2 is sintered, at least a portion of the organic binder disappears. It is preferable that almost no organic binder remains in the sintering precursor layer 2 after the sintering process, and more preferably, none of the organic binder remains.

[0020] The sinterable particles contain a conductive metal. The conductive metal 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.

[0021] In this embodiment, the sinterable particles preferably contain at least one selected from the group consisting of silver, copper, silver oxide, and copper oxide, which allows the semiconductor element to be more effectively bonded to the substrate via the small pieces of the thermal bonding sheet 10 (small pieces of the thermal bonding sheet 10').

[0022] 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 sintering precursor layer 2.

[0023] The sinterable particles preferably contain silver as the conductive metal. By including silver in the sinterable particles, the oxidation resistance of the sinterable particles is improved, and sintering can be suitably carried out even in an air atmosphere. Specifically, for example, sintering can be suitably carried out in an air atmosphere when bonding a semiconductor element such as a semiconductor chip X to a substrate. On the other hand, if the sinterable particles contain copper, for example, the sintering can be carried out in an inert environment such as nitrogen gas, as necessary, to prevent oxidation of the copper.

[0024] The sinterable particles may contain a metal oxide. For example, the surface layer of the sinterable particles may be in a state where the metal has been converted into a metal oxide.

[0025] 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 silver particles in which at least a portion of the surface is covered with silver oxide, or copper particles in which at least a portion of the surface is covered with copper oxide. The particles formed from multiple types of metals may be particles having, for example, a core portion formed from nickel, copper, silver, aluminum, or the like, and a shell portion covering at least a portion of the surface of the core portion and formed from gold, silver, copper, or the like.

[0026] Further, examples of sinterable particles include composite particles containing a metal and a material other than a metal. Examples of composite particles include particles having a core formed of resin particles or the like and a surface layer formed of a metal such as nickel or gold, covering at least a portion of the surface of the core. The core may be formed of a carbon material such as carbon black or carbon nanotubes. Examples of composite particles that can be used include metal particles whose surfaces have been treated with a fatty acid.

[0027] When the sinterable particles contain silver, more specifically, when the sinterable particles are silver particles, the silver particles may contain silver element and other elements (such as metal elements) that are unavoidable impurity elements. Alternatively, the silver particles may be surface-treated (e.g., silane coupling treatment). Examples of surface treatment agents for silver particles include fatty acid-based coating agents, amine-based coating agents, and epoxy-based coating agents.

[0028] As the silver particles, silver particles whose surface has been treated with a coating agent (hereinafter, sometimes referred to as "coating-treated silver particles") are preferred from the following viewpoints. 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 sintering precursor layer 2 before the sintering treatment. This allows the sinterable particles to be more sufficiently dispersed in the sintering precursor layer 2 before the sintering treatment. As will be explained later regarding the manufacture of a semiconductor device, by subjecting the sintering precursor layer 2 to a sintering treatment at a predetermined temperature or higher, at least a portion of the organic binder disappears from the sintering precursor layer 2.

[0029] The above sinterable particles may be used alone or in combination of two or more types.

[0030] 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 easily dispersed in the varnish used to obtain the sintering precursor layer 2, which will be described later.

[0031] 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 sintering precursor layer 2 after the sintering process. In particular, a heat transfer path is formed in the thickness direction. This allows the thermal conductivity (heat dissipation) of the sintering precursor layer 2 after the sintering process to be relatively high.

[0032] 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.

[0033] 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

[0034] 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.

[0035] The average particle size of the sinterable particles is preferably 1 nm or more, more preferably 10 nm or more, and even more preferably 50 nm or more. This can improve the dispersibility of the sinterable particles in the varnish used to obtain the sintering precursor layer 2 described below. Therefore, a sintering precursor 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 10,000 nm or less, more preferably 3,000 nm or less, more preferably 1,000 nm or less, and even more preferably 500 nm or less, which allows the sintering precursor layer 2 to have a smoother surface. The average particle size of the sinterable particles is determined by a particle size distribution measurement method, which will be described in detail later. Note that the above average particle size refers to the average particle size of all sinterable particles contained in the sintering precursor layer 2.

[0036] The sintering precursor layer 2 preferably contains sinterable particles in an amount of 60% by mass or more and 99% by mass or less, more preferably 65% ​​by mass or more and 98% by mass or less, even more preferably 70% by mass or more and 97% by mass or less, and most preferably 75% by mass or more and 97% by mass or less. From another perspective, the sintering precursor layer 2 preferably contains sinterable particles in an amount of 30% by volume or more and 70% by volume 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 X to a substrate, the bonding by the sintering precursor layer 2 after the sintering process can be sufficiently reliable.

[0037] The volume content of sinterable particles in the sintering precursor layer 2 is preferably higher than the volume content of sinterable particles in the adhesion layer 1. This can make the layer obtained by sintering the sintering precursor layer 2 denser.

[0038] The content (mass%) of sinterable particles in the sintering precursor layer 2 can be calculated from the measured amount of ash remaining after burning the sintering precursor 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 precursor 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). On the other hand, the content (volume %) of sinterable particles in the sintering precursor layer 2 is calculated by dividing the integrated value of the area of ​​the sinterable particles in an SEM image of the cross section of the sintering precursor layer 2 observed with a scanning microscope by the total area of ​​the image.

[0039] In this embodiment, the sintering precursor layer 2 preferably contains a thermally decomposable binder (particularly, a thermally decomposable polymer binder) and a readily volatile binder as organic binders. The readily volatile binder is an organic binder component that, when measured by thermogravimetric analysis (TGA), undergoes complete weight loss (all elimination to 0% weight) at a lower temperature than the thermally decomposable polymer binder.

[0040] 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 sintering precursor layer 2 in a sheet shape before the sintering process. To more fully exert 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 sintering precursor layer 2 preferably contains at least one of polycarbonate resin and acrylic resin as the thermally decomposable polymer binder. The sintering precursor layer 2 may contain only polycarbonate resin as the thermally decomposable polymer binder.

[0041] Examples of polycarbonate resins include aliphatic polycarbonates that have only aliphatic chains and do not contain aromatic structures such as benzene rings between carbonate esters (-OCOO-) in the main chain, and aromatic polycarbonates that contain aromatic structures between carbonate esters (-OCOO-) 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.

[0042] 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."

[0043] 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.

[0044] 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.

[0045] 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.

[0046] In this embodiment, the volatile binder has a viscosity of 1×10 at 23° C. 5It 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 (instrument name "HAAKE MARS III", manufactured by Thermo Fisher Scientific). Specifically, parallel plates with a diameter of 20 mm 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.

[0047] 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.

[0048] 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.

[0049] The easily volatile binder may be used alone or in combination of two or more.

[0050] As the readily volatile binder, terpene alcohols are preferred in terms of stability at room temperature, and among terpene alcohols, isobornylcyclohexanol is more preferred.

[0051] 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 sintering precursor 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, a sintering precursor layer 2 containing isobornylcyclohexanol can adequately maintain its sheet shape at room temperature and can become tacky at temperatures of 60°C or higher. Therefore, by including isobornylcyclohexanol as a volatile binder, the sintering precursor 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 sintering precursor layer 2 from lifting off the adherend. The temperature when the semiconductor element is temporarily fixed to an adherend such as a substrate via the sintering precursor layer 2 is, for example, 30°C or higher and 200°C or lower. Such a temperature is preferably 50°C or higher, more preferably 70°C or higher. At such a temperature, isobornylcyclohexanol becomes tacky for the above-mentioned reasons. Such a temperature may be 150°C or lower, or 125°C or lower.

[0052] The sintering precursor layer 2 may contain 1 mass % or more of the organic binder, or 2 mass % or more, or 3 mass % or more of the organic binder. The sintering precursor layer 2 preferably contains 3 mass % or more, and more preferably 5 mass % or more of the organic binder. The sintering precursor layer 2 may contain 40% by mass or less of the organic binder, 35% by mass or less, or 30% by mass or less. The sintering precursor layer 2 preferably contains 20% by mass or less, and more preferably 10% by mass or less of the organic binder.

[0053] When the sintering precursor layer 2 contains the above-mentioned thermally decomposable polymer binder and the above-mentioned easily volatile binder as organic binders, the proportion (%) of the thermally decomposable polymer binder in the total amount of the thermally decomposable polymer binder and the easily volatile 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 20% by mass or more and 40% by mass or less. In the sintering precursor layer 2, the content of the easily volatile binder may be greater than the content of the thermally decomposable polymer binder.

[0054] The sintering precursor layer 2 preferably contains 0.01 mass % or more of the thermally decomposable polymer 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 sintering precursor layer 2 preferably contains 20.0 mass % or less of the thermally decomposable polymer 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.

[0055] The sintering precursor layer 2 preferably contains 0.5 mass % or more of the volatile 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 sintering precursor layer 2 preferably contains 20.0 mass % or less of the easily volatile binder, more preferably 15.0 mass % or less, and even more preferably 10.0 mass % or less.

[0056] The sintering precursor layer 2 may have a single layer structure, or may have a multi-layer structure in which a plurality of layers are stacked.

[0057] In this embodiment, the thickness of the sintering precursor layer 2 is preferably 5 μm or more. The thickness of the sintering precursor layer 2 may be 300 μm or less, 200 μm or less, or 100 μm or less. The sintering precursor layer 2 may be thicker than the adhesion layer 1.

[0058] The thickness of the sintering precursor 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.

[0059] Next, the adhesive layer 1 of the heat bonding sheet 10 of this embodiment will be described in detail.

[0060] [Adhesion layer of heat bonding sheet] In this embodiment, the adhesion layer 1 contains sinterable particles and an organic binder, similar to the sintering precursor layer 2. Details of the sinterable particles and the organic binder are as described above. The following description of the adhesion layer will focus only on the differences from the description of the sintering precursor layer 2. Therefore, the same description as for the sintering precursor layer 2 will not be repeated.

[0061] When the particle size distribution of the sinterable particles contained in the adhesion layer 1 is measured, the particle size distribution has at least two peaks. Specifically, in a particle size distribution diagram obtained by measuring the particle size distribution under the following measurement conditions, at least two peaks appear on the large particle diameter side and the small particle diameter side. The peak apexes of each peak are spaced apart from each other. In the particle size distribution diagram, for example, the horizontal axis represents particle diameters in the range of 1 μm to 10,000 μm, and the vertical axis represents frequency (%). If the height of the peak apex (frequency (%)) is less than 0.1%, it is not considered to be a peak on the small particle diameter side.

[0062] For example, in the adhesion layer 1, a powder having a larger average particle size (large particle group) and a powder having a smaller average particle size (small particle group) are mixed, and thus at least two peaks appear in the particle size distribution diagram as described above. In other words, the adhesion layer 1 contains a powder of sinterable particles having a larger average particle size (large particle group) and a powder of sinterable particles having a smaller average particle size (small particle group). Because the adhesion layer 1 contains the large particle group, by mixing at least the sinterable particles and an organic binder when producing the adhesion layer 1, the organic binder is crushed into small pieces by the large particle group having a relatively large particle size, and as a result, the uniformity within the adhesion layer 1 can be relatively high. The material of the particles constituting the large particle group and the material of the particles constituting the small particle group may be the same or different. Preferably, at least a portion of the particles constituting the large particle group and at least a portion of the particles constituting the small particle group contain the same metal element. "Containing the same metal element" means both containing the same type of metal and containing compounds containing the same type of metal element (such as the same or different metal oxides). This makes it easier for particles to be sintered together within the adhesion layer 1 by sintering. Therefore, the sintering precursor layer 2 can become a denser layer after sintering.

[0063] The details of the above particle size distribution measurement method are given below. [Measurement conditions for particle size distribution measurement] Measuring equipment: Laser diffraction-scattering particle size distribution analyzer (For example, Microtrac MT3000II, manufactured by Microtrac Bell) (Pretreatment of measurement sample) Using a cryomicrotome, thin sliced ​​measurement samples are taken at least once from the surface of the adhesive layer 1, which has been frozen with liquid nitrogen. Then, 0.1 g of the sample is placed in a beaker, 1 g of an alcohol-based dispersion solvent (commonly known as "Solmix") is added, and the sample is dispersed for 10 seconds using an ultrasonic disperser. Then, the sample is measured using a laser diffraction / scattering particle size distribution analyzer under the following conditions: (Laser diffraction / scattering particle size distribution analyzer settings) Number of measurements: 2 Measurement time: 30 seconds Setting shape: spherical Measurement mode: Ag (reflect) Particle density: 10.5 Measurement solvent: ethanol Refractive index of solvent: 1.36 Measurement temperature: 25℃ Particle size distribution: volume basis Average particle size: Median diameter (D50)

[0064] The content of sinterable particles in the adhesion layer 1 is, for example, 30% by mass or more and 95% by mass or less. Such a content is preferably 60% by mass or more and 90% by mass or less. When the content is within the above numerical range, the adhesion between the adhesion layer 1 and an adherend such as a wafer can be improved. Furthermore, when the sinterable particles are sintered together by a sintering process to bond a semiconductor element such as a semiconductor chip X to a substrate, the bonding by the adhesion layer 1 after the sintering process can exhibit sufficient reliability.

[0065] The content of sinterable particles in the adhesion layer 1 is, for example, 5% by volume or more and 40% by volume or less. Such a content is preferably 15% by volume or more and 35% by volume or less. When the content is in such a numerical range, the adhesion between the adhesion layer 1 and an adherend such as a wafer can be improved. The content of sinterable particles in the adhesion layer 1 can be determined in the same manner as the volume % of sinterable particles in the sintering precursor layer 2 described above.

[0066] The proportion of the large particle group among the sinterable particles contained in the adhesion layer 1 is preferably 5% or more and 30% or less by volume %. This numerical range can improve the adhesion between the adhesion layer 1 and an adherend such as a wafer. This proportion is the proportion of sinterable particles defined as the large particle group by the above particle size distribution measurement (laser diffraction-scattering measurement) to all sintered particles, and is calculated based on volume %. Specifically, among the peaks with the highest and second highest peak heights in the particle size distribution, the peak on the large particle side is considered to be the peak of the large particle group of sinterable particles. Based on all the peaks that appear in the particle size distribution, the cumulative count number of all sinterable particles converted into a volume percentage and the cumulative count number of the peak of the large particle group are calculated. Therefore, by defining the cumulative count number of all sinterable particles converted into a volume percentage as 100%, the proportion of the large particle group to all sinterable particles is calculated as a numerical value [%]. In addition, when a peak curve extends upward from the zero point height on the vertical axis of the particle size distribution diagram on either side of a peak, the point at the zero point height on the peak curve is generally considered to be the boundary of the peak (i.e., the peak start point or end point). Furthermore, when the lowest point of the valley between two adjacent peaks is located higher than the zero point on the vertical axis of the particle size distribution diagram (when the two peaks partially overlap), in principle, a line drawn parallel to the vertical axis passing through the lowest point is considered to be the boundary between the two peaks. Furthermore, the horizontal axis (the horizontal axis passing through the zero point on the vertical axis) is considered to be the baseline of the peak. By calculating the count in the area surrounded by the boundary set as above, the baseline, and the peak curve, the proportion of the large particle group among the sinterable particles, as described above, can be determined.

[0067] The ratio (P2 / P1) of the average particle diameter P2 of the large particle group to the average particle diameter P1 of the small particle group contained in the adhesion layer 1 may be 10 or more and 1000 or less, or may be 100 or less, or 50 or less. As this ratio increases, as described above, the organic binder is crushed into smaller pieces, which may result in relatively high uniformity within the adhesion layer 1. When three or more peaks appear in the particle size distribution, one of the peaks with the highest peak height and the next highest peak in the particle size distribution that is located on the large particle side can be considered to be the peak of the large particle group of sinterable particles, and the other peak can be considered to be the peak of the small particle group of sinterable particles. The average particle diameter P1 of the small particle group and the average particle diameter P2 of the large particle group refer to the particle diameter values ​​at the respective peaks in the particle size distribution diagram. In other words, it is preferable that the ratio (P2 / P1) of the particle diameter value P2 at the peak of the large particle group to the particle diameter value P1 at the peak of the small particle group in the particle size distribution diagram is within the above range. The average particle diameter P1 of the small particle group (the particle diameter value P1 at the peak apex of the small particle group) may be, for example, 0.005 μm or more and 1 μm or less. The average particle diameter P2 of the large particle group (the particle diameter value P2 at the peak apex of the large particle group) may be, for example, 0.5 μm or more and 10 μm or less. The peaks whose apexes fall within the above ranges can be regarded as the peaks of the large particle group and the small particle group, respectively.

[0068] The adhesion layer 1 may contain the organic binder in an amount of 1% by mass or more, or 2% by mass or more, or 40% by mass or less, or 35% by mass or less.

[0069] When the adhesion layer 1 contains the above-mentioned thermally decomposable polymer binder and the above-mentioned easily volatile binder as organic binders, the proportion (%) of the thermally decomposable polymer binder in the total amount of the thermally decomposable polymer binder and the easily volatile binder is preferably 5% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 50% by mass or less. On the other hand, the content of the easily volatile binder in the adhesion layer 1 may be greater than the content of the thermally decomposable polymer binder.

[0070] The adhesive layer 1 may contain 0.01 mass % or more, or 0.05 mass % or more of the thermally decomposable polymer binder. The adhesive layer 1 may contain 20.0 mass % or less, or 10.0 mass % or less of the thermally decomposable polymer binder.

[0071] The adhesion layer 1 may contain 0.5% by mass or more, or 1.5% by mass or more, of the volatile binder. The adhesion layer 1 may contain 40.0% by mass or less, or 30.0% by mass or less, of the volatile binder.

[0072] The thickness of the adhesion layer 1 may be, for example, 1 μm or more and 100 μm or less. The thickness of the adhesion layer 1 is preferably 2 μm or more. The thickness of the adhesion layer 1 is preferably 50 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. The thickness of the adhesion layer 1 is measured in the same manner as the thickness of the sintering precursor layer 2 described above.

[0073] Next, the component migration preventing layer 3 of the heat bonding sheet 10 of this embodiment will be described in detail. The heat bonding sheet 10 may or may not include the component migration preventing layer 3.

[0074] [Component migration prevention layer of heat bonding sheet] In this embodiment, the component migration preventing layer 3 of the heat bonding sheet 10 functions as a support in the heat bonding sheet 10. The component migration preventing layer 3 contains at least a resin. The component migration preventing layer 3 is made of, for example, a plastic film.

[0075] Examples of materials for the plastic film include polyolefin resin, polyester resin, polyurethane resin, polycarbonate resin, polyether ether ketone resin, polyimide resin, polyetherimide resin, polyamide resin, wholly aromatic polyamide resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyphenyl sulfide resin, aramid resin, fluororesin, cellulose-based resin, and silicone resin. The component migration preventing layer 3 may be formed of one type of material, or may be formed of two or more types of materials.

[0076] 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.

[0077] The component migration-preventing layer 3 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 component migration-preventing layer 3 formed by laminating two or more layers formed from one type of material has a single-layer structure. On the other hand, a component migration-preventing layer 3 formed by laminating two or more layers formed from different materials has a multi-layer structure.

[0078] When the component migration-preventing layer 3 is a plastic film, the component migration-preventing layer 3 may be a non-stretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. The component migration preventing layer 3 may also be a release liner with a release-treated surface in contact with the sintering precursor layer 2. For example, a release agent may be applied to one surface of the component migration preventing layer 3 that is in contact with the sintering precursor layer 2. In this case, when manufacturing a semiconductor device, the fragmented sintering precursor layer 2 (sintering precursor layer fragments 2') can be easily peeled off from one surface of the component migration preventing layer 3 (release liner).

[0079] The thickness of the component migration preventing layer 3 is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the component migration preventing layer 3 is preferably 5000 μm or less, more preferably 4000 μm or less, and even more preferably 3000 μm or less. The thickness of the component migration prevention layer 3 is measured in the same manner as the thickness of the sintering precursor layer 2 described above.

[0080] 1B, the heat bonding sheet 100 with dicing tape of this embodiment includes the heat bonding sheet 10 described above and a dicing tape 20 superimposed on one surface of the heat bonding sheet 10. In the heat bonding sheet 100 with dicing tape, the sintering precursor layer 2 is disposed between the adhesion layer 1 and the dicing tape 20.

[0081] The dicing tape 20 includes a base layer 21 and an adhesive layer 22 overlying one side of the base layer 21. The base layer 21 of the dicing tape 20 is formed of, for example, a resin film, and the adhesive layer 22 is formed of, for example, an adhesive resin composition containing an acrylic resin. This type of dicing tape 20 is commercially available. When the heat bonding sheet 10 has the component migration preventing layer 3, for example, the component migration preventing layer 3 is superimposed on the adhesive layer 22 of the dicing tape 20. On the other hand, when the heat bonding sheet 10 does not have the component migration preventing layer 3, for example, the sintering precursor layer 2 of the heat bonding sheet 10 is superimposed on the adhesive layer 22 of the dicing tape 20.

[0082] Next, a method for producing the above-mentioned heat bonding sheet will be described.

[0083] The method for manufacturing the heat bonding sheet includes, for example, a step of preparing a sintering precursor layer, a step of preparing an adhesive layer, and a step of bonding the sintering precursor layer and the adhesive layer together. If necessary, the method further includes a step of overlaying a component migration prevention layer on one side of the sintering precursor layer.

[0084] The process for producing the sintering precursor layer includes, for example, a process for preparing a varnish containing sinterable particles containing a conductive metal, an organic binder, and an organic solvent, and a process for volatilizing the organic solvent from the varnish to produce the sintering precursor layer. The process for producing the adhesion layer includes, for example, a process for preparing a varnish containing sinterable particles containing a conductive metal, an organic binder, and an organic solvent, and a process for volatilizing the organic solvent from the varnish to produce the adhesion layer.

[0085] The process for producing the sintering precursor layer and the process for producing the adhesion layer are almost the same. Specific examples of each process are as follows. In the process of preparing the varnish, for example, the varnish is prepared 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.

[0086] As the organic solvent, for example, alcohols such as ethanol, or ketones such as methyl ethyl ketone (MEK) can be used.

[0087] 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.

[0088] The solid content concentration in the varnish is, for example, 30% by mass or more and 80% by mass or less. The solid content concentration in the varnish may be 40% by mass or more, or 50% by mass or more. The solid content concentration in the varnish may be 70% by mass or less. The solid content is the components excluding the organic solvent, and is, for example, the total content of the sinterable particles and the organic binder described above.

[0089] The viscosity of the varnish at 23°C is, for example, 1.0 [Pa·s] to 7.0 [Pa·s]. 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.

[0090] In the step of producing the sintering precursor layer, for example, a coating film is formed by applying a varnish to a release liner to a predetermined thickness, and then the coating film is heated to volatilize the organic solvent. In the step of forming the adhesive layer, for example, a varnish is applied to a release liner to a predetermined thickness to form a coating film, and then the coating film is heated to volatilize the organic solvent.

[0091] In the step of bonding the sintering precursor layer and the adhesive layer, the sintering precursor layer on the release liner and the adhesive layer on the release liner are overlapped. If necessary, the release liner attached to the sintering precursor layer is removed and a component migration prevention layer is superimposed on the exposed sintering precursor layer, or the release liner attached to the sintering precursor layer may be left as it is as a component migration prevention layer.

[0092] The heat bonding sheet 10 manufactured as described above can be used as an auxiliary member when manufacturing a semiconductor device, for example.

[0093] [Method of using the heat bonding sheet (semiconductor device manufacturing method)] Next, an example of a method for manufacturing a semiconductor device using the thermal bonding sheet 10 according to this embodiment will be described with reference to the drawings. In the manufacturing method of a semiconductor device, the adherend to which the adhesion layer 1 or sintering precursor layer 2 of the heat bonding sheet 10 is bonded is not limited to the following examples. Examples of such adherends include semiconductor wafers, substrates, heat sinks, and clips (used in so-called clip bonding). Other examples of adherends include metal pads and metal plates. For example, a laminate (first laminate) of the adhesion layer 1 and the sintering precursor layer 2 may be bonded to one side of a semiconductor chip, and the semiconductor chip and the adherend may be bonded via the first laminate. Then, a laminate (second laminate) of the adhesion layer 1 and the sintering precursor layer 2 may be bonded to the other side of the semiconductor chip. The semiconductor chip may then be bonded to a metal pad or metal plate via the second laminate. In such a case, for example, the adhesion layer 1 of the first laminate may be bonded to a semiconductor wafer (semiconductor chip), and the adhesion layer 1 of the second laminate may be bonded to a metal pad or metal plate.

[0094] The manufacturing method of the semiconductor device according to this embodiment is carried out using, for example, a semiconductor wafer W for obtaining a plurality of semiconductor chips X, a substrate having a plurality of mounting areas on which the plurality of semiconductor chips X are mounted, the above-mentioned heat bonding sheet 10, a dicing tape 20 (see FIG. 1B), and a pressing member used to temporarily fix each of the plurality of semiconductor chips X to the plurality of mounting areas.

[0095] The following description will be given taking as an example a case where a semiconductor chip X 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 ceramic insulating layer D, and a copper die pad E and a thin copper layer F respectively disposed on both sides of the ceramic insulating layer D. The copper die pad E is an area where the semiconductor chip X is mounted (hereinafter also simply referred to as the mounting area) (see FIG. 3A).

[0096] First, a semiconductor wafer W is cut on a dicing tape 20 to obtain a plurality of semiconductor chips X from the semiconductor wafer W (see FIGS. 2A and 2B). Specifically, the semiconductor wafer W is attached to the exposed surface of the heat bonding sheet 10, and a dicing ring R is attached to the adhesive layer 22 of the dicing tape 20. The semiconductor wafer W is then divided into a plurality of small pieces to obtain the semiconductor chips X. More specifically, the heat bonding sheet 10 and the semiconductor wafer W are cut (so-called full cut) into small pieces using a dicing saw S or the like, and the small pieces of the heat bonding sheet 10' and the semiconductor chips X are fabricated on the dicing tape 20. A commercially available product can be used as the dicing tape 20. If the heat bonding sheet 10 includes a component migration preventing layer 3 that is a release liner, the adhesion layer 1 and the sintering precursor layer 2 other than the component migration preventing layer 3 may be cut (so-called half cut) from the heat bonding sheet 10. In this case, the fragmented sintering precursor layer 2 (sintering precursor layer fragments 2') can be peeled off from one side of the component migration preventing layer 3 (release liner), and the semiconductor chip X and the heat bonding sheet fragments 10' can be picked up, as will be described in detail later.

[0097] The resulting semiconductor chip X has, for example, a rectangular thin plate shape. The thickness of the semiconductor chip X is, for example, 10 μm or more and 500 μm or less. The thickness of the semiconductor chip X is preferably 20 μm or more and 400 μm or less. The area of ​​the semiconductor chip X 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:

[0098] Next, as shown in Fig. 2C, the semiconductor chip X with the piece 10' of the heat bonding sheet attached thereto is peeled off from the adhesive layer 22 of the dicing tape 20. More specifically, with the dicing tape 20 with the dicing ring R attached fixed by the holder Q, the pin member P is raised to push up the semiconductor chip X to be picked up and the piece 10' of the heat bonding sheet through the dicing tape 20. The pushed-up semiconductor chip X and the piece 10' of the heat bonding sheet are held by the collet A.

[0099] 2A and 2B, the following steps may be performed: Specifically, as shown in FIG. 2D, a semiconductor wafer W on a dicing tape 20 is subjected to stealth dicing to form a plurality of weakened regions T for cleavage inside the semiconductor wafer W. In the stealth dicing process, a laser beam focused at a focused point is irradiated onto the interior of the semiconductor wafer W. This results in ablation due to multiphoton absorption, forming a weakened region T within the semiconductor wafer W. Note that, before or after the stealth dicing process, a grinding process may be performed on the back side of the semiconductor wafer W to thin the semiconductor wafer W.

[0100] The semiconductor wafer W that has undergone the stealth dicing process is cleaved along the weakened region T by expanding the dicing tape 20, as shown in FIG. 2E, for example. Specifically, first, the dicing tape 20 carrying the semiconductor wafer W that has undergone the stealth dicing process is fixed to a holder Q of an expanding device. Next, the dicing tape 20 is stretched (expanded) so as to increase its area, thereby cleaving the semiconductor wafer W. Specifically, multiple push-up members U are raised from below the dicing tape 20 to stretch (expand) the dicing tape 20 in the planar direction. The temperature condition during the expansion is, for example, −20°C or higher and 70°C or lower. This expansion forms cracks in the weakened region T in the semiconductor wafer W, dividing the semiconductor wafer W into small pieces, resulting in semiconductor chips X. Then, the push-up members U are lowered, and the expanded state of the dicing tape 20 is released. After the expansion, the dicing tape 20 may be heated and shrunk in the portion on the outer periphery side of the group of semiconductor chips X. The heating temperature is, for example, 100° C. or more and 300° C. or less. By carrying out such a process, the semiconductor chip X can be formed on the dicing tape 20. Then, as shown in FIG. 2C, the semiconductor chip X with the thermal bonding sheet piece 10′ attached thereto is peeled off from the adhesive layer 22 of the dicing tape 20.

[0101] Subsequently, a substrate (for example, a laminate of a ceramic insulating layer D, a copper die pad E, and a copper thin layer F) is separately placed on a stage H (see FIG. 3A). Then, while holding the semiconductor chip X, collet A, which has been set to a temperature within a range of 25°C to 150°C, is lowered vertically, so that the small piece 10' of the heat bonding sheet attached to the semiconductor chip X abuts against the copper die pad E. Next, collet A presses (presses) the semiconductor chip X against the copper die pad E. After performing each of the above operations to temporarily fix one semiconductor chip X to the copper die pad E, the same operations are repeated. As a result, the plurality of semiconductor chips X are temporarily fixed to the copper die pad E via the small pieces 10' of the heat bonding sheet (see FIGS. 3A and 3B). The pressure when pressing the semiconductor chip X 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.

[0102] The substrate to which the thermal bonding sheet piece 10' is attached may be a lead frame. A typical lead frame can be used. For example, a Cu frame plated with Ag, or a Cu frame plated with Ni, Pd, and Au in that order (Palladium Pre-Plated Lead Frame, Pd-PPF) can be used.

[0103] When temporarily fixing each semiconductor chip X, the collet A may be heated to a temperature at which the sinterable particles contained in the thermal bonding sheet pieces 10' can be sintered. This may perform a primary sintering process of the sinterable particles contained in the thermal bonding sheet pieces 10'.

[0104] If the sinterable particles contained in the thermal bonding sheet piece 10' 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 X can be more firmly bonded to the copper die pad E via the thermal bonding sheet piece 10'. In other words, the bonding reliability of the semiconductor chip X to the substrate is further improved.

[0105] 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.

[0106] The primary sintering process may be performed by heating not only the collet A but also the stage H at the same temperature. This heats the thermal bonding sheet piece 10' from both sides in the thickness direction, allowing the sinterable particles to be sintered more thoroughly. This allows the semiconductor chip X to be more fully bonded to the copper die pad E via the thermal bonding sheet piece 10'. In other words, the bonding reliability of the semiconductor chip X to the substrate is further improved.

[0107] The temperature of the heated stage H is preferably equal to or lower than the temperature that suppresses oxidation of the copper die pad E or the copper thin layer F. The heating temperature of the stage H is preferably 150° C. or lower.

[0108] When the primary sintering process is carried out as described above, for example, the temperature of collet A may be lowered to a temperature (e.g., 50°C) at which the sinterable particles become difficult to sinter by lifting collet A after the primary sintering process to separate the semiconductor chip X from collet A. When the primary sintering process is performed on each of all the small pieces 10' of the heat bonding sheet, bonding wires may be bonded to required locations after all the semiconductor chips X have been bonded.

[0109] In the method for manufacturing a semiconductor device according to this embodiment, after the plurality of semiconductor chips X are temporarily fixed to the substrate, a heating step may be performed in which the thermal bonding sheet pieces 10' are heated to a temperature at which the sinterable particles can be sintered. In the heating step, heating may be performed while applying a compressive force in the thickness direction to at least one of the plurality of thermal bonding sheet pieces 10'. 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).

[0110] More specifically, in the method for manufacturing a semiconductor device according to this embodiment, the sintering process can be carried out as follows. In the heating step of the sintering treatment, for example, at least one of the plurality of thermal bonding sheet pieces 10' is heated while being pressed in the thickness direction. Specifically, after the semiconductor chip X is temporarily fixed, a heating and pressurizing device configured to be capable of heating may be used to heat the thermal bonding sheet pieces 10' while applying a compressive force in the thickness direction. The heating and pressing device is composed of two flat plates Z, Z, as shown in Fig. 3C, for example. The two flat plates Z, Z are respectively arranged to sandwich a stage H, a substrate (ceramic insulating layer D, copper die pad E, and copper thin layer F), and a plurality of semiconductor chips X. Then, by applying a force that reduces the distance between the two heated flat plates, the thermal bonding sheet piece 10' is heated while being pressed. By carrying out the heating process in this manner, the plurality of thermal bonding sheet pieces 10' can be heated while being pressed, and the semiconductor chip X can be firmly bonded to the substrate (copper die pad E) via the thermal bonding sheet pieces 10'. This improves the bonding reliability of the semiconductor chip X to the substrate. After the heating step is performed in this manner, bonding wires may be bonded to required locations.

[0111] On the other hand, in the heating step, after all the semiconductor chips X to be bonded have been temporarily fixed, the thermal bonding sheet pieces 10' may be heated without applying a compressive force in the thickness direction to the thermal bonding sheet pieces 10'. At this time, the heating is performed at a temperature at which the sinterable particles contained in the thermal bonding sheet pieces 10' can be sintered (for example, a temperature in the range of 200°C to 400°C). The heating may be performed, for example, by heating the stage H, or by using an oven or a reflow furnace. Even when such a heating step is performed, the semiconductor chip X can be firmly bonded to the substrate (copper die pad E) via the small pieces 10' of the thermal bonding sheet. Therefore, the bonding reliability of the semiconductor chip X to the substrate can be improved.

[0112] In the method for manufacturing a semiconductor device according to this embodiment, further steps may be performed. For example, a wire bonding step may be carried out to electrically connect a part of the semiconductor chip X to a part of the substrate. Alternatively, a sealing step may be performed in which the semiconductor chip X and the small piece 10' of the heat-bonding sheet are sealed with a thermosetting resin such as epoxy resin. In the sealing step, a heat treatment is performed at a temperature of, for example, 150° C. or higher and 200° C. or lower to promote the curing reaction of the thermosetting resin.

[0113] The heat bonding sheet of this embodiment is as exemplified above, but the present invention is not limited to the heat bonding sheet exemplified above. That is, various forms used in general heat bonding sheets and the like can be adopted within the scope that does not impair the effects of the present invention.

[0114] The matters disclosed by this specification include the following. (1) a sintering precursor layer containing sinterable particles and an adhesion layer overlying one surface of the sintering precursor layer, the adhesion layer includes an organic binder and sinterable particles, and the content of the sinterable particles in the adhesion layer is 5% by volume or more and 40% by volume or less; A heat bonding sheet, wherein the particle size distribution of the sinterable particles contained in the adhesive layer has at least two peaks when the particle size distribution is measured. (2) The heat bonding sheet according to (1) above, wherein the volume content of the sinterable particles in the sintering precursor layer is higher than the volume content of the sinterable particles in the adhesive layer. (3) The heat bonding sheet according to (1) or (2) above, wherein the sintering precursor layer contains 30% by volume or more and 70% by volume or less of the sinterable particles. (4) The heat bonding sheet according to any one of (1) to (3) above, wherein the adhesion layer contains 15% by volume or more and 35% by volume or less of the sinterable particles. (5) When the peak having the highest peak height and the peak having the next highest peak height, which are on the large particle side in the particle size distribution, are defined as the peaks of the large particle group of the sinterable particles, A heat bonding sheet according to any one of (1) to (4) above, wherein the proportion of sinterable particles of the large particle group among the sinterable particles contained in the adhesion layer is 5% or more and 30% or less by volume %. (6) The heat bonding sheet according to any one of (1) to (5) above, wherein the sintering precursor layer and the adhesion layer each contain a thermally decomposable binder as an organic binder. (7) The heat bonding sheet according to any one of (1) to (6) above, wherein the thickness of the sintering precursor layer is 5 μm or more and 100 μm or less, and the thickness of the adhesion layer is 2 μm or more and 20 μm or less. (8) A heat bonding sheet according to any one of (1) to (7) above and a dicing tape superimposed on one surface of the heat bonding sheet, A heat-bonding sheet with dicing tape, wherein the sintering precursor layer of the heat-bonding sheet is disposed between the adhesion layer and the dicing tape. (9) The heat bonding sheet further includes a component migration prevention layer, The heat bonding sheet according to (8) above, wherein the component migration prevention layer is disposed between the sintering precursor layer and the dicing tape. [Example]

[0115] 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.

[0116] (raw material for sintering precursor layer) [Sinterable particles] ·First silver particles (small particle group): Average particle size 60nm, manufactured by DOWA Electronics ·Second silver particles (large particle group): Average particle size 1100nm, manufactured by Mitsui Mining & Smelting Co., Ltd. [Organic binder] Thermally decomposable polymer binder: Polycarbonate resin: Product name: "QPAC40" manufactured by Empower Materials Volatile binder: Isobornylcyclohexanol Product name: Tersolv MTPH, manufactured by Nippon Terpene Chemical Co., Ltd. Organic solvent: methyl ethyl ketone (MEK) [Release liner] One pair of release-treated film (product name "MRA38", manufactured by Mitsui Plastics Co., Ltd.)

[0117] Example 1 [Preparation of sintered precursor layer] The varnish was prepared by dissolving or suspending the first silver particles (90 parts by mass), the second silver particles (10 parts by mass), the thermally decomposable polymer binder (4 parts by mass), and the readily volatile binder (12 parts by mass) in methyl ethyl ketone (MEK). Specifically, the mixture was stirred for 3 minutes in stirring mode using a hybrid mixer (model "HM-500", manufactured by Keyence Corporation). Next, varnish was applied to one surface of one of the release liners, and then heated at 110° C. for 3 minutes to form a sintered precursor layer having a thickness of 25 μm. [Creating the adhesion layer] The first silver particles (80 parts by mass) and second silver particles (20 parts by mass) were weighed out in the amounts shown in Table 1, and these silver particles, a thermally decomposable polymer binder (13 parts by mass), and a volatile binder (37 parts by mass) were dissolved or suspended in methyl ethyl ketone (MEK) to prepare a varnish in the same manner as described above. Next, varnish was applied to one surface of the other release liner, and then heated at 110° C. for 3 minutes to form an adhesive layer having a thickness of 10 μm. The content of all sinterable particles in the adhesion layer was measured by the above-mentioned method, and as a result, in Example 1, the total content of the first silver particles and the second silver particles in the adhesion layer was 30% by volume. [Preparation of heat-bonding sheet] The sintering precursor layer on the release liner and the adhesive layer on the release liner, each prepared as described above, were bonded together to produce a heat bonding sheet.

[0118] (Examples 2 to 7, Comparative Example 1) Heat bonding sheets were produced in the same manner as in Example 1, except that the compositions were changed to those shown in Tables 1 and 2. The component compositions of the adhesive layers in each Example and Comparative Example are shown in Tables 1 and 2, respectively.

[0119] [Table 1]

[0120] [Table 2]

[0121] [Measurement of particle size distribution of sinterable particles contained in the adhesive layer] The particle size distribution of the sinterable particles contained in the adhesive layer of each of the thermal bonding sheets manufactured as described above was measured according to the measurement method and conditions described above. The measurement results are shown in Tables 1 and 2. For example, in Example 1, the proportion of the second silver particles (large particle group) to all sinterable particles in the adhesive layer was 20% based on the volume content. For the adhesive layer of each Example, two peaks were confirmed in the particle size distribution diagram. Specific examples of the particle size distribution diagram after measurement (Example 5, Comparative Example 1) are shown in FIG. On the other hand, for the adhesive layer of Comparative Example 1, only one peak was confirmed in the particle size distribution diagram.

[0122] <SAT (ultrasonic testing) test (evaluation of adhesive layer uniformity)> A Cu substrate (20 mm × 20 mm × 3 mm) plated with Ag (5 μm thick) and a Si chip (5 mm × 5 mm × 0.2 mm) plated with Ti (0.1 μm thick) and Ag (0.75 μm thick) were prepared. Each thermal bonding sheet (comprising only a sintering precursor layer and an adhesive layer) was sandwiched between the Cu substrate and the Si chip to produce a test laminate. The test laminate was then subjected to a sintering bonding process under conditions of 300°C / 10 MPa / 2.5 minutes. The sintered laminate was evaluated for bonding conditions at the interface between the Cu substrate and the sintered adhesion layer and at the interface between the Si chip and the sintered adhesion layer by ultrasonic flaw detection images. Equipment: "FineSAT200" manufactured by Hitachi Power Solutions Probe: PQ2-50-13 (reflection mode) Number of measurement points: 600 x 600 (within a square area of ​​21 mm on each side) Criteria: (Good) The image had a uniform color tone across the entire bonding area. (Failure) Weak ultrasonic reflection was confirmed in 10% or more of the area within the bonding area.

[0123] Regarding the results of the evaluation of the uniformity of the adhesive layer, examples of ultrasonic flaw detection images are shown in Fig. 5. In Fig. 5, the results of Example 1 and Comparative Example 1 are excerpted. As can be seen from the above evaluation results, the adhesive layer of the heat bonding sheet of each example contains sinterable particles that show two peaks, one on the large particle side and one on the small particle side, in particle size distribution measurement, and therefore the dispersibility of the organic binder was good and the uniformity within the layer was good. On the other hand, the adhesion layer of the comparative example contained sinterable particles for which one peak was observed in particle size distribution measurement, and therefore the dispersibility of the organic binder was not necessarily good, and the uniformity inside the layer was low.

[0124] <Peeling test of adhesive layer on wafer (evaluation of adhesive layer adhesion)> Each heat-bonding sheet, including only the sintering precursor layer and adhesive layer, was cut to prepare test samples measuring 10 mm x 100 mm. The test samples were attached to a Si wafer (150 mm diameter, 550 μm thick) plated with Ti (0.1 μm thick) and Ag (0.75 μm thick). While heated on a hot plate at 70°C, the test samples were pressed onto the Si wafer by rolling a 2 kg roller back and forth. Each heat-bonding sheet was pressed onto the Si wafer so that the Si wafer and adhesive layer were in contact. After pressing, the sheets were left at room temperature for 30 minutes. Using a Tensilon tester, the test samples were peeled from the Si wafer in a 180° direction at a tensile speed of 300 mm / min. The adhesive strength during peeling was measured. The results are shown in Tables 1 and 2, respectively.

[0125] As can be seen from the results of the adhesion evaluation above, when the proportion of the first silver particles and the second silver particles in the adhesion layer was within a specific range, and when the proportion of the second silver particles in the total amount of the first silver particles and the second silver particles was within a specific range, the adhesion to the wafer was good. [Industrial Applicability]

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

[0127] 10: Heat bonding sheet, 1: adhesion layer, 2: sintering precursor layer, 3: component migration prevention layer, 100: Heat bonding sheet with dicing tape, 20: dicing tape, 21: base layer, 22: adhesive layer, A: Collet, X: Semiconductor chip, D: Ceramic insulating layer, E: Copper die pad, F: Copper thin layer, H: Stage.

Claims

1. a sintering precursor layer containing sinterable particles and an adhesion layer overlying one surface of the sintering precursor layer, the adhesion layer includes an organic binder and sinterable particles, and the content of the sinterable particles in the adhesion layer is 5% by volume or more and 40% by volume or less; A heat bonding sheet, wherein when the particle size distribution of the sinterable particles contained in the adhesive layer is measured, the particle size distribution has at least two peaks.

2. The heat bonding sheet according to claim 1 , wherein a volume content of the sinterable particles in the sintering precursor layer is higher than a volume content of the sinterable particles in the adhesive layer.

3. The heat bonding sheet according to claim 1 or 2, wherein the sintering precursor layer contains the sinterable particles in an amount of 30% by volume or more and 70% by volume or less.

4. The heat bonding sheet according to claim 1 or 2, wherein the adhesion layer contains the sinterable particles in an amount of 15% by volume or more and 35% by volume or less.

5. When the peak having the highest peak height and the peak having the next highest peak height, which are on the large particle side in the particle size distribution, are defined as the peaks of the large particle group of the sinterable particles, 3. The heat bonding sheet according to claim 1, wherein the proportion of the sinterable particles of the large particle group among the sinterable particles contained in the adhesion layer is 5% or more and 30% or less by volume.

6. The heat bonding sheet according to claim 1 or 2, wherein the sintering precursor layer and the adhesion layer each contain a thermally decomposable binder as an organic binder.

7. 3. The heat bonding sheet according to claim 1, wherein the thickness of the sintering precursor layer is 5 μm or more and 100 μm or less, and the thickness of the adhesive layer is 2 μm or more and 20 μm or less.

8. A heat bonding sheet according to claim 1 or 2, and a dicing tape superimposed on one surface of the heat bonding sheet, A heat-bonding sheet with dicing tape, wherein the sintering precursor layer of the heat-bonding sheet is disposed between the adhesion layer and the dicing tape.

9. The heat bonding sheet further includes a component migration prevention layer, 9. The heat bonding sheet with dicing tape according to claim 8, wherein the component migration prevention layer is disposed between the sintering precursor layer and the dicing tape.

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