Method for manufacturing laminate

Abstract

To provide a method for manufacturing a laminate, capable of being obtained without using mechanical pressure means or by applying pressure to the entire substrate.SOLUTION: A method for manufacturing a laminate includes: a first step of obtaining a laminate precursor by sandwiching a film-like sintered material that contains metal particles and binder components between a first substrate and a second substrate; and a second step of heating the laminate precursor and pressurizing the atmosphere in which the laminated precursor is present to decompose and vaporize the binder components.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a laminate.

Background Art

[0002] In recent years, with the increase in voltage and current in automobiles, air conditioners, personal computers, etc., the demand for semiconductor devices (for example, power devices) mounted on these has been increasing. Semiconductor devices may be used under high voltage and high current, and in this case, a large amount of heat is likely to be generated from the semiconductor device. Therefore, it is necessary to efficiently release the heat generated from the semiconductor device. Conventionally, in order to release the heat generated from a semiconductor device to the outside, a heat sink (for example, a heat sink) may be attached around the semiconductor device. Therefore, a method for obtaining a laminate having good thermal conductivity between the heat sink and the semiconductor device is required. In addition, there is a desire to form a bonding material between a power semiconductor device and a substrate from a metal having high thermal conductivity and high heat resistance.

[0003] For example, Patent Document 1 proposes "a method for manufacturing a laminate including a step of providing a film-shaped firing material containing sinterable metal particles and a binder component, having the same shape or substantially the same shape as and the same size as a semiconductor chip to be attached, on a support sheet; a step of attaching the film-shaped firing material on the support sheet to a substrate; a step of peeling the support sheet from the substrate and the film-shaped firing material; a step of attaching the back side of the semiconductor chip to face the film-shaped firing material on the substrate; and a step of sintering and bonding the semiconductor chip and the substrate by heating the film-shaped firing material to 200°C or higher." Further, it is proposed to "heat the film-shaped firing material to 200°C or higher and apply pressure at 5 MPa or higher." For example, Patent Document 2 proposes "a thermosetting sheet containing a thermosetting resin, a volatile component, and conductive particles, wherein the weight loss rate W1 when heated from room temperature to 100°C at a heating rate of 10°C / min under a nitrogen gas flow of 200 mL / min and held at 100°C for 30 min is 0.5 mass% or less, and the weight loss rate W2 when heated from 100°C to 200°C at a heating rate of 10°C / min under a nitrogen gas flow of 200 mL / min and held at 200°C for 30 min is 2 mass% or more."

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, when pressurizing the laminate, relatively high pressure conditions of 5 MPa or more are employed. In such cases, it is common to pressurize using mechanical pressurizing means such as a flip chip bonder or a flat plate press. However, the devices used for mechanically pressurizing methods are not common in the field of semiconductor processing, and new devices had to be introduced for semiconductor processing using such thermally conductive bonding materials. In addition, these mechanical pressurizing means have a limitation in that they can apply pressure only in the direction parallel to the thickness direction of the semiconductor element.

[0006] One problem to be solved by an embodiment of the present disclosure is to provide a method for manufacturing a laminate in which a laminate can be obtained without using mechanical pressurizing means (for example, a flat plate press) or by applying pressure to the entire adherend (that is, applying pressure in the thickness direction of the adherend and in directions other than the thickness direction of the adherend).

Means for Solving the Problems

[0007] The present disclosure includes the following embodiments. <1> A first step of obtaining a laminate precursor by sandwiching a film-shaped firing material containing metal particles and a binder component between a first adherend and a second adherend; A second step of heating the laminate precursor and pressurizing the atmosphere in which the laminate precursor is present to decompose and vaporize the binder component; A method for manufacturing a laminate including: <2> The method for manufacturing a laminate according to <1>, wherein the pressure of the atmosphere is 0.15 MPa or more and 3.00 MPa or less. <3> In the second step, while heating the laminate precursor at a temperature equal to or higher than the decomposition start temperature of the resin contained in the binder component and lower than the melting point of the metal particles, the atmosphere is pressurized to obtain a second laminate precursor in a first treatment; A second treatment of heating the second laminate precursor at a temperature equal to or higher than the melting point of the metal particles, the method for manufacturing a laminate according to <1> or <2>. <4> The method for manufacturing a laminate according to any one of <1> to <3>, wherein the second step is a step performed in an autoclave. <5> The method for manufacturing a laminate according to any one of <1> to <4>, wherein the binder component contains a resin having a decomposition start temperature of 200° C. or lower. <6> The method for manufacturing a laminate according to any one of <1> to <5>, wherein the binder component contains a thermoplastic resin, and the proportion of the content of the thermoplastic resin in the total amount of the binder component is 50% by mass or more. <7> The method for manufacturing a laminate according to any one of <1> to <6>, wherein the first adherend is a semiconductor element.

Advantages of the Invention

[0008] According to an embodiment of the present disclosure, there is provided a method for manufacturing a laminate in which a laminate can be obtained without using mechanical pressing means (for example, a flat press machine) or by applying pressure to the entire adherend (that is, applying pressure in the thickness direction of the adherend and in directions other than the thickness direction of the adherend).

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments which are examples of the present invention will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the invention. In the numerical ranges described step by step in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerically described range. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0011] Each component may contain a plurality of corresponding substances. When referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition.

[0012] <Method for Manufacturing a Laminate> The method for manufacturing a laminate according to the present disclosure includes a first step of obtaining a laminate precursor by sandwiching a film-shaped firing material containing metal particles and a binder component between a first adherend and a second adherend, and a second step of heating the laminate precursor and pressurizing the atmosphere in which the laminate precursor exists to decompose and vaporize the binder component.

[0013] According to the method for manufacturing a laminate according to the present disclosure, a laminate can be obtained without using mechanical pressing means or by applying pressure to the entire adherend (i.e., applying pressure in the thickness direction of the adherend and in directions other than the thickness direction of the adherend). Here, the laminate means a laminate in which a first adherend, a sintered body, and a second adherend are laminated in this order. Further, the sintered body included in the laminate is obtained by decomposing and vaporizing the binder component contained in the film-shaped firing material through the first step and the second step, and melting and bonding the metal particles contained in the film-shaped firing material to each other.

[0014] In the first step, a laminate precursor is obtained by sandwiching a film-shaped firing material containing metal particles and a binder component between a first adherend and a second adherend. Then, in the second step, while heating the laminate precursor, the atmosphere in which the laminate precursor exists is pressurized, so that the binder component contained in the film-shaped firing material is decomposed and vaporized, discharged from the film-shaped firing material, and the metal particles contained in the film-shaped firing material are melted and bonded to each other to form a sintered body. And by joining the sintered body to the first adherend and the second adherend, a laminate in which the first adherend, the sintered body, and the second adherend are laminated in this order can be obtained.

[0015] Details of the method for manufacturing a laminate according to the present disclosure will be described below, but the present disclosure is not limited thereto.

[0016] (First Step) The first step is a step of obtaining a laminate precursor by sandwiching a film-shaped firing material containing metal particles and a binder component between a first adherend and a second adherend.

[0017] -Object to be coated- The first object to be coated and the second object to be coated are not particularly limited, and examples thereof include semiconductor wafers, semiconductor elements, substrates, lead frames, heat sinks (such as heat sinks), and the like. The film-shaped firing material according to the present disclosure is preferably applied to the use of joining a semiconductor element and other components. Therefore, it is preferable that at least the first object to be coated is a semiconductor element. When the first object to be coated is a semiconductor element, examples of the second object to be coated include substrates, other semiconductor elements, lead frames, heat sinks, and the like. Examples of the heat sink include a heat sink made of a metal plate such as a copper plate, and a heat pipe or the like can also be used.

[0018] As a combination of the first object to be coated and the second object to be coated, it is preferable that the first object to be coated is a semiconductor element and the second object to be coated is a substrate or another semiconductor element. In particular, the semiconductor element to be joined is preferably a power semiconductor element (a semiconductor element with a rated current of 1 A or more), and the semiconductor wafer is preferably a semiconductor wafer for power semiconductor elements. According to the method for manufacturing a laminate according to the present disclosure, a laminate having a sintered body with high thermal conductivity can be obtained. From this, according to the method for manufacturing a laminate according to the present disclosure, a laminate capable of more efficiently releasing heat generated from a semiconductor element can be obtained.

[0019] -Film-shaped firing material- The film-shaped firing material contains metal particles and a binder component. ·Metal particles The film-shaped firing material contains metal particles. By including metal particles, the metal particles are melted and bonded to each other through the second step, and a sintered body is obtained. By forming the sintered body, the first object to be coated and the second object to be coated in contact with the film-shaped firing material are joined.

[0020] Examples of the material of the metal particles include metals such as silver, gold, copper, iron, nickel, aluminum, silicon, palladium, platinum, and titanium; oxides of these metals; alloys containing at least two of these metals; barium titanate; and the like. From the viewpoint of making a sintered body whose melting point can be easily adjusted so that it can be melted at a relatively low temperature, it is preferable that the metal particles contain silver. The silver content in the metal particles is preferably 20% by mass or more, more preferably 30% by mass or more of the metal particles. The metal particles may be silver particles composed of at least one of silver and its oxide.

[0021] From the viewpoint of improving the compatibility with the binder component, the surface of the metal particles may be coated with an organic substance. Examples of the organic substance include alcohol molecule derivatives and amine molecule derivatives derived from alcohol molecules having 1 to 12 carbon atoms.

[0022] The shape of the metal particles may be any of spherical, plate-like, etc., and is preferably spherical. The spherical metal particles may be true spheres or ellipsoids.

[0023] The particle size of the metal particles varies depending on the ratio of the content of the sinterable metal particles and the non-sinterable metal particles described later, but may be 0.1 nm or more and 10,000 nm or less, may be 0.3 nm or more and 3,000 nm or less, or may be 0.5 nm or more and 1,000 nm or less.

[0024] The particle size of the metal particles is measured with an electron microscope. The method for measuring the particle size of the metal particles is as follows. The film-like firing material is observed with an electron microscope, and 100 or more metal particles are randomly selected. The projected area of the selected metal particles is calculated, and the equivalent circle diameter corresponding to the projected area is calculated for each. The number average value of the calculated equivalent circle diameters is taken as the particle size of the metal particles.

[0025] The metal particles may contain two or more types of metal particles having different particle sizes. Specifically, it may contain metal particles with a particle size of 100 nm or less and metal particles with a particle size exceeding 100 nm. Here, the metal particles with a particle size of 100 nm or less are referred to as "sinterable metal particles". Also, the metal particles with a particle size exceeding 100 nm are referred to as "non-sinterable metal particles". When the size of metal particles becomes smaller down to the nano level, they have the characteristic that the melting point gradually decreases (melting point depression). Therefore, by selecting metal particles with a small size, metal particles with a low melting point can be obtained. From the viewpoint of performing sintering of the film-shaped firing material at a low temperature, at least some of the metal particles are preferably sinterable metal particles with a large melting point depression. Further, from the viewpoint that after sintering of the film-shaped firing material for heating and pressing, the non-sinterable metal particles bond to the molten sinterable metal particles to efficiently obtain a sintered body, the metal particles preferably contain both sinterable metal particles and non-sinterable metal particles.

[0026] The particle size of the sinterable metal particles may be selected so as to cause an appropriate melting point depression according to the temperature at which the film-shaped firing material is sintered, and may be 0.1 nm or more and 100 nm or less, may be 0.3 nm or more and 50 nm or less, or may be 0.5 nm or more and 30 nm or less. The particle size of the non-sinterable metal particles may be more than 150 nm and 50000 nm or less, may be 150 nm or more and 10000 nm, or may be 180 nm or more and 5000 nm or less.

[0027] The particle size of the sinterable metal particles is measured in the same manner as the measurement procedure for the particle size of the above-described metal particles. In addition, in the measurement of the particle size of the sinterable metal particles, the metal particles to be selected are limited to metal particles having a circle equivalent diameter corresponding to the projected area of 100 nm or less.

[0028] The particle size of the non-sinterable metal particles is measured in the same manner as the measurement procedure for the particle size of the above-described metal particles. In addition, in the measurement of the particle size of the non-sinterable metal particles, the metal particles to be selected are limited to metal particles having a circle equivalent diameter corresponding to the projected area exceeding 100 nm.

[0029] While forming a sintered body with few voids, when a film-shaped sintering material is used for bonding semiconductor elements as described later, from the viewpoint of improving the adhesiveness before sintering to semiconductor elements or other components, the content of metal particles (the total content of sinterable metal particles and non-sinterable metal particles; the same shall apply hereinafter) is preferably 50% by mass or more and 98% by mass or less, more preferably 70% by mass or more and 97% by mass or less, still more preferably 80% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less with respect to the entire film-shaped sintering material.

[0030] From the viewpoint of making it easy to form a sintered body even at low-temperature sintering because the film-shaped sintering material for heating and pressing contains a certain amount of metal particles with a large melting point depression, when the metal particles contain sinterable metal particles, the content of the sinterable metal particles is preferably 20% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 95% by mass or less with respect to the content of the metal particles.

[0031] ·Binder component The binder component contains a resin. From the viewpoint of being easily decomposable by heating compared with a thermosetting resin and the viewpoint of hardly generating voids in the sintered body by plasticizing during heating, the resin contained in the binder component is preferably a thermoplastic resin. Examples of the thermoplastic resin include polycarbonate resins (for example, specific resins described later), acrylic resins, polylactic acid, cellulose derivatives such as ethyl cellulose, and polyvinyl alcohol. The proportion of the content of the thermoplastic resin in the total amount of the binder component is preferably 50% by mass or more. The proportion of the content of the thermoplastic resin in the total amount of the binder component is preferably 60% by mass or more, more preferably 70% by mass or more. Further, from the viewpoint of facilitating the adoption of means for pressurizing the atmosphere in which the laminate precursor exists, the binder component preferably contains a resin (hereinafter also referred to as "specific resin") having a decomposition start temperature of 200°C or lower.

[0032] Since the specific resin has a decomposition start temperature of 200°C or lower, it easily decomposes and vaporizes even under relatively mild heating conditions. Therefore, even when using an autoclave or the like, which is a pressurizing device, to pressurize the atmosphere in which the laminate precursor exists, it is easy to decompose and vaporize. The decomposition start temperature of the specific resin is preferably 80°C or higher and 200°C or lower, and more preferably 100°C or higher and 185°C or lower. From the viewpoint of easily obtaining a sintered body that easily decomposes and vaporizes under relatively mild heating conditions and has few voids, it is preferable that the above-described thermoplastic resin corresponds to the specific resin.

[0033] Further, when the decomposition temperature of the resin contained in the binder component in the film-shaped firing material exceeds 200°C, the difference between the melting point of the metal particles and the decomposition temperature of the resin may become small. In that case, the decomposition of the binder component and the melting of the metal particles may proceed simultaneously. As a result, it is easy to form a state in which the metal particles are melted and bonded to surround the binder component before the sintered body in which most of the binder component has decomposed is obtained. Further, when such a molten state of the metal particles is formed, since the metal particles are melted and bonded together, the shape of the particles is not maintained and the melting point has increased. Therefore, the sintered body obtained by decomposing the binder component from such a molten state may be an incomplete one that forms voids derived from the region where the binder component existed. Moreover, it was difficult to remelt such an incomplete sintered body to eliminate voids and aggregate the metals due to the increase in the melting point of the metal. On the other hand, when the decomposition start temperature of the specific resin is 200°C or lower, the difference between the melting point of the metal particles and the decomposition temperature of the specific resin becomes large. Therefore, by heating and pressurizing, the decomposition and vaporization of the binder component proceed first. Then, the metal particles densely accumulate, and an aggregate of the metal particles is obtained. By further heating the aggregate, the metal particles are melted and bonded together, and a more complete sintered body is obtained. As described above, if the film-shaped firing material has a decomposition start temperature of 200°C or lower, an aggregate in which metal particles are densely accumulated can be obtained. Therefore, it becomes difficult for the metal particles to melt and form a bond so as to surround the binder component. Further, since the metal particles contained in the aggregate maintain the shape of the particles, the melting point of the metal particles is less likely to rise above the initial value. Therefore, the metal particles contained in the aggregate are easily melted by heating, and a sintered body with few voids is easily obtained.

[0034] The decomposition start temperature of the resin is a value measured using a differential thermal thermogravimeter. Using a differential thermal-thermogravimetric simultaneous measurement device (for example, DTG-60 manufactured by Shimadzu Corporation), the temperature is raised from room temperature (25°C) to 400°C at a heating rate of 20°C / min under a nitrogen atmosphere to measure the thermal decomposition behavior. The decomposition start temperature is defined as the temperature at the intersection of a line parallel to the horizontal axis passing through the mass before the start of the test heating and a tangent line drawn so that the gradient between the inflection points in the decomposition curve is maximized.

[0035] From the viewpoint that a resin with a low decomposition start temperature is easily obtained, the specific resin is preferably an aliphatic polycarbonate. An aliphatic polycarbonate is a polycarbonate in which the polymer main chain consists of an aliphatic hydrocarbon group and a carbonate group (in this specification, a group represented by -O-CO-O-). The aliphatic polycarbonate may have a side chain.

[0036] The number of carbon atoms of the aliphatic hydrocarbon group contained in the polymer main chain is preferably 1 or more and 6 or less, more preferably 2 or more and 4 or less, and still more preferably 2 or 3.

[0037] From the viewpoint of making the decomposition start temperature of the specific resin a lower value, the specific resin is preferably an aliphatic polycarbonate containing an organic acid group. Examples of the organic acid group include a carboxy group and a sulfo group. From the viewpoint of simplifying the synthesis procedure of the aliphatic polycarbonate and improving the handleability, the organic acid group is preferably a carboxy group.

[0038] Since the specific resin contains an organic acid group, the acidity derived from the organic acid group promotes the decomposition of the specific resin. Therefore, the decomposition start temperature becomes lower.

[0039] From the viewpoint of simplifying the synthesis procedure of the aliphatic polycarbonate, the aliphatic polycarbonate containing an organic acid group is preferably an aliphatic polycarbonate containing a group represented by the following formula (0). Formula (0) *-(CH2) m -COOH In formula (0), m represents an integer of 1 or more. Note that * represents a bond.

[0040] From the viewpoint of reducing the influence of the side chain on the physical properties of the aliphatic polycarbonate, m is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and still more preferably 1 or 2.

[0041] More specifically, the aliphatic polycarbonate containing an organic acid group preferably contains a structural unit represented by the following formula (1).

[0042]

Chemical formula

[0043] In formula (1), R 1 , R 2 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and n is 1 or 2.

[0044] In formula (1), the number of carbon atoms of the alkyl group is 1 to 10, and preferably 1 to 4. Examples of the alkyl group include linear or branched substituted or unsubstituted alkyl groups. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, and the like. The alkyl group may be substituted with a substituent selected from an alkoxy group, an ester group, a silyl group, a sulfanyl group, a cyano group, a nitro group, a sulfo group, a formyl group, an aryl group, a halogen atom, and the like.

[0045] In formula (1), the number of carbon atoms of the aryl group is 6 to 20, preferably 6 to 14. Examples of the aryl group include a phenyl group, an indenyl group, a naphthyl group, a tetrahydronaphthyl group, and the like. The aryl group may be substituted with, for example, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group; another aryl group such as a phenyl group, a naphthyl group, an alkoxy group, an ester group, a silyl group, a sulfanyl group, a cyano group, a nitro group, a sulfo group, a formyl group, a halogen atom, and other substituents.

[0046] From the viewpoint of adjusting the number of organic acid groups present in the molecule, the aliphatic polycarbonate containing an organic acid group preferably contains a structural unit represented by the following formula (2) together with the structural unit represented by the above formula (1).

[0047]

Chemical formula

[0048] In formula (2), R 4 , R 5 and R 6 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and X is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, a group containing an ether bond, a group containing an ester bond, or an allyl group.

[0049] In formula (2), the alkyl group has 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms. Examples of the alkyl group include linear or branched substituted or unsubstituted alkyl groups. Examples of the alkyl group include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, and the like. The alkyl group may be substituted, for example, with an alkoxy group, an ester group, a silyl group, a sulfanyl group, a cyano group, a nitro group, a sulfo group, a formyl group, an aryl group, a halogen atom, or the like.

[0050] In formula (2), the aryl group has 6 to 20 carbon atoms, preferably 6 to 14 carbon atoms. Examples of the aryl group include, for example, phenyl group, indenyl group, naphthyl group, tetrahydronaphthyl group, and the like. The aryl group may be substituted, for example, with an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group; another aryl group such as a phenyl group, a naphthyl group; a substituent such as an alkoxy group, an ester group, a silyl group, a sulfanyl group, a cyano group, a nitro group, a sulfo group, a formyl group, a halogen atom, or the like.

[0051] In formula (2), X is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, an ether bond-containing group, an ester bond-containing group, or an allyl group. X is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or a methyl group.

[0052] The alkyl group having 1 to 10 carbon atoms represented by X is preferably an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, and the like.

[0053] The number of carbon atoms in the haloalkyl group is from 1 to 10, preferably from 1 to 4. Examples of the haloalkyl group include a fluoromethyl group, a chloromethyl group, a bromomethyl group, an iodomethyl group and the like.

[0054] As the ether bond-containing group, an alkyl group having 1 to 4 carbon atoms substituted with an alkoxy group having 1 to 4 carbon atoms, an allyloxy group or the like is preferable, and examples thereof include a methoxymethyl group, an ethoxymethyl group, an allyloxymethyl group and the like.

[0055] As the ester bond-containing group, an alkyl group having 1 to 4 carbon atoms substituted with an acyloxy group having 1 to 4 carbon atoms, a benzyloxycarbonyl group or the like is preferable, and examples thereof include an acetoxymethyl group, a butyryloxymethyl group and the like.

[0056] From the viewpoint of facilitating the lowering of the decomposition start temperature of the aliphatic polycarbonate, the content of the structural unit represented by the formula (1) in the aliphatic polycarbonate is preferably 0.001 mol% or more and 30 mol% or less, more preferably 0.1 mol% or more and 20 mol% or less, still more preferably 0.5 mol% or more and 20 mol% or less, and particularly preferably 1.0 mol% or more and 20 mol% or less, based on all the structural units constituting the aliphatic polycarbonate. From the viewpoint of reducing the influence of acid on articles to which the film-shaped firing material according to the present disclosure, such as semiconductor elements, is applied, the content of the structural unit represented by the formula (1) in the aliphatic polycarbonate may be 0.1 mol% or more and 5.0 mol% or less, or 0.5 mol% or more and 3.0 mol% or less, based on all the structural units constituting the aliphatic polycarbonate.

[0057] The content of the structural unit represented by the formula (2) in the aliphatic polycarbonate is preferably 70 mol% or more and 99.999 mol% or less, more preferably 80 mol% or more and 99.9 mol% or less, still more preferably 80 mol% or more and 99.5 mol% or less, and particularly preferably 90 mol% or more and 99.0 mol% or less, based on all the structural units constituting the aliphatic polycarbonate.

[0058] The weight average molecular weight of the aliphatic polycarbonate is preferably 3,000 or more and 1,000,000 or less, more preferably 10,000 or more and 500,000 or less, and even more preferably 10,000 or more and 300,000 or less, from the viewpoints of easily maintaining the film shape of the heat and pressure resistant film-like firing material according to the present disclosure and adjusting the viscosity of the composition for film formation.

[0059] The weight average molecular weight of the aliphatic polycarbonate is a value measured by gel permeation chromatography (GPC). The weight average molecular weight of the aliphatic polycarbonate is measured as follows. A chloroform solution with an aliphatic polycarbonate concentration of 0.5 mass% is prepared and measured using GPC. After the measurement, the weight average molecular weight is calculated by comparing with polystyrene with a known weight average molecular weight measured under the same conditions. The measurement conditions are as follows. Column: GPC column (trade name of Showa Denko K.K., Shodex K-804L) Column temperature: 40 °C Eluent: Chloroform Flow rate: 1.0 mL / min

[0060] Specific examples of the aliphatic polycarbonate include those in which, for R 1 , R 2 , R 3 , and n in formula (1), respectively, R 1 , R 2 and R 3 are all hydrogen atoms, n is 1, and for R 4 , R 5 , R 6 , and X in formula (2), respectively, R 4 , R 5 , and R 6 are all hydrogen atoms, X is a methyl group, and the aliphatic polycarbonate containing only the structural units represented by formula (1) and formula (2) can be mentioned.

[0061] When such an aliphatic polycarbonate is synthesized by adjusting the content of the structural unit represented by the formula (1) in the aliphatic polycarbonate within the range of 1.0 mol% to 20 mol% in all the structural units constituting the aliphatic polycarbonate, the mass reduction rate described below can be set within a predetermined range, and the decomposition start temperature can be set to 200 °C or lower. For example, even when the content of the structural unit represented by the formula (1) in the aliphatic polycarbonate is as low as 3.0 mass mol% or less in all the structural units constituting the aliphatic polycarbonate, an aliphatic polycarbonate having a mass reduction rate of about 95 mass% and a decomposition start temperature of about 150 °C can be obtained.

[0062] From the viewpoint of facilitating the reduction of the decomposition start temperature of the aliphatic polycarbonate, specifically, the aliphatic polycarbonate is preferably a compound represented by the following formula (3).

[0063]

Chemical formula

[0064] In the formula (3), m and l represent the content (unit: mol%) of the structural unit with respect to all the structural units constituting the aliphatic polycarbonate.

[0065] When the decomposition start temperature of the aliphatic polycarbonate is 200 °C or lower, it is preferable that almost all of the mass of the aliphatic polycarbonate disappears due to decomposition when heating is maintained for a certain period of time even at a low temperature. Therefore, the mass reduction rate after holding at 160 °C for 1 hour in thermogravimetric analysis measurement is preferably 90% or more, and more preferably 95% or more. From the viewpoint of preventing the decomposition of the binder component before heating, the mass reduction rate after holding at 100 °C for 1 hour is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less. Note that the decomposition start temperature can be adjusted by the content of the structural unit represented by the formula (1).

[0066] The mass reduction rate is measured by a thermogravimetric analysis measuring device. As the thermogravimetric analysis measuring device, for example, DTG-60 manufactured by Shimadzu Corporation, which is a differential thermal-thermogravimetric simultaneous measuring device, can be used. A measurement sample is added to the thermogravimetric analysis measurement, and the temperature is raised from room temperature to a predetermined temperature (160 °C or 100 °C) at a heating rate of 50 °C / min under a nitrogen atmosphere, and then held at that temperature for 1 hour to measure the thermal decomposition behavior. The mass reduction rate is calculated from the ratio [(W0 - W1) / W0 × 100] by reading the mass (W1) after 1 hour of heating from the decomposition curve and the initial mass (W0).

[0067] The glass transition temperature of the aliphatic polycarbonate is preferably 0 °C or higher and 50 °C or lower, more preferably 10 °C or higher and 40 °C or lower, and still more preferably 15 °C or higher and 30 °C or lower, from the viewpoints of the strength of the film-shaped fired material and the flexibility of the film-shaped fired material.

[0068] The glass transition temperature of the aliphatic polycarbonate is the temperature at the peak of the differential thermal curve measured by a differential scanning calorimeter for the aliphatic polycarbonate.

[0069] The content of the specific resin with respect to the entire binder component is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and still more preferably 80% by mass or more and 100% by mass or less.

[0070] · Other resins The binder component may contain other resins other than the specific resin. Examples of other resins other than the specific resin include acrylic resins, polylactic acid, and cellulose derivatives. The content of other resins other than the specific resin is preferably 0% by mass or more and 50% by mass or less, more preferably 0% by mass or more and 30% by mass, still more preferably 0% by mass or more and 20% by mass or less, and particularly preferably 0% by mass, with respect to the entire binder component.

[0071] · Content of the binder component From the viewpoint of facilitating the decomposition of the binder component without leaving it by sintering, the content of the binder component is preferably 2% by mass or more and 50% by mass or less, more preferably 3% by mass or more and 30% by mass or less, and still more preferably 5% by mass or more and 20% by mass or less with respect to the entire film-shaped sintering material.

[0072] - Other components - The film-shaped sintering material may contain other components other than metal particles and the binder component. Examples of other components include solvents, dispersants, plasticizers, tackifiers, storage stabilizers, defoamers, thermal decomposition accelerators, and antioxidants.

[0073] - Thickness of the film-shaped sintering material - The thickness of the film-shaped sintering material is not particularly limited, but is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, and still more preferably 30 μm or more and 90 μm or less.

[0074] The thickness of the film-shaped sintering material is measured in accordance with JIS K7130 (1999). In accordance with JIS K7130 (1999), the thicknesses at any five locations of the measurement object are measured, and the arithmetic mean value of the obtained values is taken as the thickness of the film-shaped sintering material. Note that a constant-pressure thickness measuring instrument can be used as the thickness measuring instrument.

[0075] The first step will be specifically described with reference to FIG. 4. In the first step, a film-shaped sintering material 22 containing metal particles 30 and a binder component 31 is sandwiched between a first adherend 20 and a second adherend 21. Thereby, a laminate precursor 200 in which the first adherend 20, the second adherend 21, and the film-shaped sintering material 22 are laminated is obtained.

[0076] - An example of the specific procedure of the first step - When sandwiching a film-shaped firing material between a first adherend and a second adherend, for example, the following method may be used. Attach one surface of the film-shaped firing material to the surface of the first adherend. Then, a method of attaching the second adherend to one surface of the film-shaped firing material so as to face the first adherend through the film-shaped firing material can be mentioned.

[0077] -Another example of the specific procedure of the first step- When sandwiching a film-shaped firing material between a first adherend and a second adherend, for example, a method using a film-shaped firing material with a support sheet may be used.

[0078] ·Film-shaped firing material with a support sheet The film-shaped firing material with a support sheet has a support sheet and a film-shaped firing material provided on the support sheet.

[0079] Also, for the film-shaped firing material with a support sheet, it is preferable that the support sheet has a base film and an adhesive layer provided on the base film.

[0080] The film-shaped firing material with a support sheet is preferably also used as a dicing sheet used when obtaining semiconductor elements by cutting a semiconductor wafer into a large number of chips (hereinafter also referred to as "dicing").

[0081] The film-shaped firing material with a support sheet will be described with reference to FIGS. 1 and 2. Note that the film-shaped firing material with a support sheet is not limited to this.

[0082] FIGS. 1 and 2 show schematic cross-sectional views of the film-shaped firing material with a support sheet. The film-shaped firing materials with support sheets 100a and 100b include a film-shaped firing material 1 and a support sheet 2.

[0083] The support sheet 2 preferably has a base film 3 and an adhesive layer 4 as shown in FIGS. 1 and 2. The adhesive layer 4 can facilitate laminating a film-shaped firing material for heating and pressing on the support sheet and facilitate dicing described later, and can also be given a function of fixing the ring frame 5. Note that the ring frame 5 is disposed on the film-shaped firing materials 100a and 100b with the support sheet to fix the film-shaped firing materials 100a and 100b with the support sheet during dicing of the semiconductor wafer, and is not a member constituting the film-shaped firing materials 100a and 100b with the support sheet. The adhesive layer 4 may be provided on the entire surface of the base film 3 as shown in FIG. 1, or may be provided along the outer periphery of the base film 3 as shown in FIG. 2.

[0084] FIG. 3 shows a schematic perspective view of the film-shaped firing material 100b with the support sheet. As shown in FIG. 3, the film-shaped firing material 100b with the support sheet may be circular along the shape of the semiconductor wafer. Although a schematic perspective view of the film-shaped firing material 100a with the support sheet is not shown, it may be circular along the shape of the semiconductor wafer.

[0085] Hereinafter, each configuration of the film-shaped firing material with the support sheet will be described in detail.

[0086] (Support Sheet) The support sheet is not particularly limited as long as a film-shaped firing material can be provided on the support sheet. The support sheet may have only the base film, or may have the base film and an adhesive layer provided on the base film. From the viewpoint of adjusting the adhesiveness between the support sheet and the film-shaped firing material for heating and pressing and facilitating dicing, the support sheet preferably has the base film and an adhesive layer provided on the base film.

[0087] -Base Film- The material of the base film is not particularly limited, and examples thereof include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-propylene copolymer, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid methyl copolymer, ethylene-(meth)acrylic acid ethyl copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyurethane film, ionomer, and the like. When higher heat resistance is required for the support sheet, examples of the material of the base film include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polypropylene and polymethylpentene; and the like.

[0088] When the base film does not have an adhesive layer, the surface may be treated with a release agent. As the release agent, for example, alkyd-based release agents, silicone-based release agents, fluorine-based release agents, unsaturated polyester-based release agents, polyolefin-based release agents, wax-based release agents, and the like are used. From the viewpoint of heat resistance, at least one selected from the group consisting of alkyd-based release agents, silicone-based release agents, and fluorine-based release agents is preferable as the release agent.

[0089] The thickness of the base film is not particularly limited, and for example, it is preferably 30 μm or more and 300 μm or less, and more preferably 50 μm or more and 200 μm or less. By setting the thickness of the base film within the above numerical range, even if dicing is performed, the base film is less likely to break. In addition, sufficient flexibility is imparted to the film-shaped sintered material with a support sheet, so that good adhesiveness is exhibited to an adherend (for example, a semiconductor wafer or the like).

[0090] The shape of the base film is preferably adjusted as appropriate according to the shape of the adherend. For example, when the adherend is a semiconductor wafer, the shape of the film-shaped sintered material is preferably circular. When the shape of the base film is circular, the diameter is preferably 10 mm or more and 500 mm or less.

[0091] As the base film, one type of base film may be used, or two or more types of base films may be laminated and used.

[0092] -Adhesive layer- The adhesive layer is a layer having adhesiveness capable of fixing the film-shaped sintered material on the support sheet. Further, in the present disclosure, for example, when the film-shaped sintered material with a support sheet is used as a dicing sheet, an instrument (for example, a ring frame) for fixing the film-shaped sintered material with a support sheet during dicing can be fixed. It is preferable that the ring frame can be peeled off after dicing.

[0093] Examples of the material of the adhesive layer include general-purpose adhesives such as rubber-based, acrylic-based, silicone-based, urethane-based, and vinyl ether-based adhesives. Focusing on the functions that can be imparted to the adhesive layer, it can be formed by an adhesive with surface irregularities, an energy ray-curable adhesive, an adhesive containing a thermal expansion component, etc.

[0094] From the viewpoint of the peelability of the film-shaped sintered material, the adhesive force of the adhesive layer to the SUS plate at 23°C is preferably 30 mN / 25 mm to 120 mN / 25 mm, more preferably 50 mN / 25 mm to 100 mN / 25 mm, and even more preferably 60 mN / 25 mm to 90 mN / 25 mm.

[0095] The thickness of the adhesive layer is not particularly limited. For example, it is preferably 1 μm or more and 100 μm or less, more preferably 2 μm or more and 80 μm or less, and even more preferably 3 μm or more and 50 μm or less.

[0096] The adhesive layer may be disposed on the entire surface of the base film or on a part of the base film. When disposed on a part of the base film, the adhesive layer is preferably disposed along the contour of the shape of the base film in a plan view of the base film.

[0097] When disposed on the entire surface of the base film, the shape of the adhesive layer is the same as the shape of the base film. When disposed on a part of the base film, the shape of the adhesive layer is preferably ring-shaped.

[0098] (Film-shaped sintered material) The composition of the film-shaped sintered material included in the film-shaped sintered material with a support sheet is the same as the above-described sintered material, and the preferred embodiments are as described above.

[0099] The shape of the film-shaped sintered material is not particularly limited, and it may be a single-sheet shape, a long film shape, etc. The long film-shaped sintered material is preferably a wound roll. Also, from the viewpoint of reducing the amount of relatively expensive metal particles to be discarded, it is preferable to appropriately adjust the shape of the film-shaped sintered material according to the shape of the adherend. For example, when the adherend is a semiconductor wafer, the shape of the film-shaped sintered material is preferably circular. When the shape of the film-shaped sintered material is circular, the diameter is preferably 10 mm or more and 500 mm or less.

[0100] (Other members) The film-shaped sintered material with a support sheet may have other members other than the support sheet and the film-shaped sintered material. Examples of other members include a protective sheet. The protective sheet is a sheet for avoiding contact between the outside and the surfaces of the film-shaped sintered material and the adhesive layer until the film-shaped sintered material with a support sheet is used. The protective sheet is not particularly limited, and examples thereof include sheets made of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, etc.

[0101] · An example of the specific procedure of the first step using a film-shaped sintered material with a support sheet The film-shaped sintered material with a support sheet is preferably used as a bonding material for bonding a semiconductor element and other components (adherends) as described above, and further preferably also serves as a dicing sheet. Hereinafter, as an example of the specific procedure of the first step using the film-shaped sintered material with a support sheet, a dicing method of a semiconductor wafer and a bonding method of a semiconductor element using the film-shaped sintered material with a support sheet will be described as examples. In the description of the first step using the film-shaped sintered material with a support sheet below, the semiconductor element refers to a chip obtained by dicing a semiconductor wafer.

[0102] The first step using the film-shaped sintered material with a support sheet is A step (1-1) of attaching a film-shaped sintered material with a support sheet (for example, reference numeral 100a in FIG. 1 or reference numeral 100b in FIG. 2) to the back surface of a semiconductor wafer (hereinafter simply referred to as "semiconductor wafer") having a circuit formed on its front surface, A step (1-2) of dicing the semiconductor wafer to obtain semiconductor elements, A step (1-3) of peeling the semiconductor element and the film-shaped sintered material (for example, reference numeral 1 in FIG. 1 or FIG. 2) and the support sheet (for example, reference numeral 2 in FIG. 1 or FIG. 2) to obtain an element with a film-shaped sintered material, A method may also include a step (1-4) of attaching the element with a film-shaped sintered material to the surface of the adherend.

[0103] - Step (1-1)- Step (1-1) is a step of attaching a film-shaped sintered material with a support sheet to the back surface of the semiconductor wafer. Attach the film-shaped sintered material in the film-shaped sintered material with a support sheet to the back surface of the semiconductor wafer so that the film-shaped sintered material adheres. By doing so, a laminate A in which the support sheet, the film-shaped sintered material, and the semiconductor wafer are laminated in this order is obtained.

[0104] The diameter of the semiconductor wafer is not particularly limited, but it is preferably smaller than the inner diameter of the ring frame (for example, reference numeral 5 in FIG. 1 or FIG. 2). Examples of the semiconductor wafer include a silicon wafer; a compound semiconductor wafer such as a silicon carbide wafer, gallium arsenide, or gallium nitride; and the like. When the semiconductor element is used as a power semiconductor, if it operates at a relatively low temperature, the semiconductor wafer may be a silicon wafer. However, when assuming operation at a higher temperature, the semiconductor wafer is preferably a compound semiconductor wafer, and as the compound semiconductor, silicon carbide or gallium nitride is preferred. It is preferable that a circuit is previously formed on the surface of the semiconductor wafer. The formation of the circuit on the semiconductor wafer can be performed by a conventionally widely used method such as an etching method or a lift-off method. It is preferable that the opposite surface (back surface) of the circuit surface of the semiconductor wafer is previously ground. The grinding method is not particularly limited, and known means using a grinder or the like can be mentioned.

[0105] - Step (1-2) - Step (1-2) is a step of dicing the semiconductor wafer to obtain semiconductor elements. More specifically, it is a step of dicing the above laminate A for each circuit formed on the surface of the semiconductor wafer to obtain a laminate B in which a support sheet, a film-shaped firing material, and semiconductor elements are laminated in this order. Dicing is preferably performed so as to cut both the semiconductor wafer and the film-shaped firing material. The dicing cut depth may completely cut the film-shaped firing material, but it is preferably up to the middle of the layer of the film-shaped firing material. The dicing method is not particularly limited. For example, after fixing the peripheral portion of the support sheet (the outer peripheral portion of the support) with a ring frame, a method of fragmenting the wafer with a rotating circular blade such as a dicing blade can be mentioned. The means for cutting the semiconductor wafer is not limited to that using a cutting blade, and dicing using a laser, dicing using plasma treatment, etc. can also be performed. Dicing using a laser may be a dicing method in which a modified region serving as a fracture starting point is formed in the semiconductor wafer by the laser, and the semiconductor wafer is fractured at the modified region by a mechanical action such as expansion of the support sheet.

[0106] - Step (1-3)- Step (1-3) is a step of separating the semiconductor chip and the film-shaped sintered material from the support sheet to obtain an element with a film-shaped sintered material. The method of separating the semiconductor element and the film-shaped sintered material from the support sheet is not particularly limited, and a method using a collet or the like can be mentioned. By separating the semiconductor element and the film-shaped sintered material from the support sheet, a laminate C (element with a film-shaped sintered material) in which the film-shaped sintered material and the semiconductor element are laminated in this order is obtained. Here, the semiconductor element in the element with a film-shaped sintered material corresponds to the first adherend.

[0107] - Step (1-4)- Step (1-4) is a step of attaching the element with a film-shaped sintered material to the surface of the second adherend. Specifically, it is a step of attaching the element with a film-shaped sintered material to the surface of the second adherend by bringing the surface having the film-shaped sintered material of the chip with a film-shaped sintered material into contact with the surface of the second adherend. By this step, a laminate precursor in which the first adherend (semiconductor element in the first step using the film-shaped sintered material with a support sheet) and the second adherend sandwich the film-shaped sintered material is obtained.

[0108] (Second Step) The second step is a step of heating the laminate precursor and pressurizing the atmosphere in which the laminate precursor exists, thereby decomposing and vaporizing the binder component. In the second step, since the pressurizing means pressurizes the atmosphere in which the laminate precursor exists, this step can be carried out without introducing a special device such as a flat press. Also, by pressurizing the atmosphere in which the laminate precursor exists, pressure can be applied to the laminate precursor not only in its thickness direction (vertical direction) but also from the horizontal direction (direction orthogonal to the vertical direction), etc. Therefore, it is expected that the metal particles in the film-shaped sintering material will aggregate more, and by compressing the film-shaped sintering material only in the thickness direction, the possibility that the ends of the film-shaped sintering material will protrude from the adherend can be reduced. By passing through the second step, the binder component contained in the film-shaped sintering material decomposes and vaporizes, the decomposed and vaporized gas is discharged, and the metal particles contained in the film-shaped sintering material melt and bond to form a sintered body. Then, by joining the sintered body to the first adherend and the second adherend, a laminate in which the first adherend, the sintered body, and the second adherend are laminated in this order can be obtained.

[0109] The heating temperature is preferably 150°C or higher and 600°C or lower, more preferably 165°C or higher and 450°C or lower, and still more preferably 180°C or higher and 300°C or lower. The pressure of the atmosphere in which the laminate precursor exists is pressurized to a pressure exceeding atmospheric pressure (0.101 MPa).

[0110] The pressure of the atmosphere in which the laminate precursor exists is preferably 0.15 MPa or more and 3.00 MPa or less, more preferably 0.50 MPa or more and 3.00 MPa or less, still more preferably 1.00 MPa or more and 3.00 MPa or less, and particularly preferably 1.50 MPa or more and 3.00 MPa or less. When the binder component contains a specific resin with a decomposition start temperature of 200° C. or lower, as described above, a sintered body with small voids is likely to be obtained. Therefore, even if the pressure in the second step is relatively low as described above, there is a high possibility of obtaining a sintered body with few voids.

[0111] When the second step is carried out in a single treatment at a temperature equal to or higher than the melting point of the metal particles without performing the first treatment and the second treatment described later, for example, the time of the second step is preferably 5 seconds to 180 minutes, more preferably 5 seconds to 150 minutes, and still more preferably 10 seconds to 120 minutes.

[0112] The apparatus applicable to the second step is not particularly limited, and any apparatus capable of heating and pressurizing the atmosphere in which the laminate precursor exists can be used. Usually, such an apparatus includes a pressure vessel. In the second step, although the atmosphere is pressurized, mechanical pressurizing means (such as a flat plate press) may be used in addition. Specific examples of the apparatus capable of heating and pressurizing include an apparatus for pressurizing the atmosphere in a pressure vessel with a compressor, an apparatus for heating a liquid in a pressure vessel and pressurizing the inside of the pressure vessel with the saturated vapor pressure of the liquid at the heating temperature, etc. Examples of such an apparatus include an autoclave. Generally, such a pressurizing apparatus equipped with a pressure vessel has an upper limit of about 300° C. as the heating temperature. When the binder component in the film-shaped sintered material contains a specific resin with a low decomposition start temperature, it is possible to easily decompose the specific resin even under such relatively mild sintering conditions.

[0113] From the viewpoint of being commonly used as a means for pressurizing the atmosphere in the pressure vessel, the second step is preferably carried out in an autoclave. The autoclave is not particularly limited as long as it can perform heating and pressurization.

[0114] The following describes a specific procedure for performing the second step in an autoclave, but it is not limited thereto.

[0115] First, place the laminate precursor in the autoclave. At this time, the placement method of the laminate precursor is not particularly limited. For example, a horizontal table can be installed in the autoclave, and the laminate precursor can be placed on it.

[0116] Subsequently, seal the autoclave and heat and pressurize the inside of the autoclave. The heating method is not particularly limited. For example, heating may be performed using a heating device provided in the autoclave, or it may be performed by flowing steam through a jacket (steam flow path) of an autoclave equipped with a jacket.

[0117] The pressurization method is not particularly limited. For example, the water supplied into the autoclave is heated to a temperature exceeding 100°C to increase the saturated vapor pressure to atmospheric pressure or higher for pressurization, or a method of supplying a gas (such as nitrogen or air) pressurized by a compressor into the autoclave for pressurization, etc. can be mentioned.

[0118] The second step may be performed by changing the heating and pressurization conditions in two steps. For example, in the second step, a first treatment of obtaining a second laminate precursor by heating the laminate precursor at a temperature equal to or higher than the resin decomposition start temperature contained in the binder component and lower than the melting point of the metal particles while pressurizing the atmosphere in which the laminate precursor exists, and a second treatment of heating the second laminate precursor at a temperature equal to or higher than the melting point of the metal particles are preferably included. In the second step including the two-step treatment, in either or both of the first treatment and the second treatment, the atmosphere in which the laminate precursor exists is pressurized, and it is preferable that the atmosphere in which the laminate precursor exists is pressurized at least in the first treatment. Here, the laminate precursor mentioned here includes the second laminate precursor described later.

[0119] - First process - In the first process, while heating the laminate precursor at a temperature equal to or higher than the decomposition start temperature of the resin contained in the binder component and lower than the melting point of the metal particles, the atmosphere in which the laminate precursor exists is pressurized to obtain a second laminate precursor.

[0120] The first process involves heating and pressurizing at a temperature lower than the melting point of the metal particles. Therefore, melting of the metal particles contained in the film-like firing material is suppressed. As a result, it is possible to more efficiently suppress the melting of the metal particles while allowing the decomposition and vaporization of the binder component to proceed.

[0121] In the first process, the heating temperature is preferably at least 15°C higher than the decomposition start temperature of the resin (e.g., a specific resin) contained in the binder component, and more preferably at least 30°C higher than the decomposition start temperature of the resin contained in the binder component. For example, the heating temperature can be 150°C or higher, more preferably 165°C or higher, and even more preferably 180°C or higher. If the heating temperature is within such a range, for example, when a specific resin is contained in the binder component and the decomposition start temperature of the specific resin is 150°C, the heating temperature can be made significantly higher than the decomposition temperature of the specific resin. The upper limit of the heating temperature is preferably at most 20°C lower than the melting point of the metal particles, and more preferably at most 40°C lower than the melting point of the metal particles. For example, in the first process, the heating temperature can be less than 250°C, preferably 230°C or lower, and more preferably 210°C or lower. If the heating temperature is within such a range, for example, when the melting point of the metal particles is 250°C, the heating temperature can be made significantly lower than the melting point of the metal particles.

[0122] In the first treatment, the heating temperature is preferably not lower than a temperature 15°C higher than the decomposition start temperature of the resin contained in the binder component and not higher than a temperature 20°C lower than the melting point of the metal particles, and more preferably not lower than a temperature 30°C higher than the decomposition start temperature of the resin contained in the binder component and not higher than a temperature 40°C lower than the melting point of the metal particles.

[0123] Thus, the first treatment is carried out under relatively mild conditions among the sintering treatments of the film-shaped sintering material, and generally has an upper limit of about 300°C as the heating temperature. It is also easy to perform heating and pressurization by a device equipped with a pressure vessel. In the first treatment, when pressurizing the atmosphere in which the laminate precursor exists, the pressure of the atmosphere is preferably 0.50 MPa or more and 3.00 MPa or less, more preferably 1.00 MPa or more and 3.00 MPa or less, and still more preferably 1.50 MPa or more and 3.00 MPa or less.

[0124] The first treatment is preferably carried out until the binder component decomposes and vaporizes. The time required for the decomposition and vaporization of the binder component can be calculated, for example, by measuring the mass change of the film-shaped sintering material with respect to temperature using a differential thermal thermogravimeter.

[0125] The time of the first treatment is preferably appropriately changed according to the composition of the binder component and the metal particles, preferably 5 seconds to 180 minutes, more preferably 5 seconds to 150 minutes, and still more preferably 10 seconds to 120 minutes.

[0126] -Second treatment- In the second treatment, the second laminate precursor is heated at a temperature equal to or higher than the melting point of the metal particles. In the second treatment, the second laminate precursor may be pressurized or heated without pressurization.

[0127] By performing the second treatment, the metal particles melt and bond to each other, thereby obtaining a sintered body. Since the binder component is decomposed and vaporized through the first process, after the first process, the metal particles are densely aggregated. Therefore, even without mechanical pressure treatment, the metal particles are in a state where they are likely to melt and bond. As a result, in the second process, when the second laminate precursor is heated without being pressurized or when the atmosphere in which the second laminate precursor exists is pressurized at a relatively low pressure, a sintered body with good thermal conductivity is easily obtained.

[0128] In the second process, the heating temperature is preferably 600°C or lower, more preferably 450°C or lower, and even more preferably 300°C or lower. As the lower limit of the heating temperature, it is preferably a temperature 20°C or higher than the melting point of the metal particles, and more preferably a temperature 40°C or higher than the melting point of the metal particles. For example, in the second process, the heating temperature can be 250°C or higher, preferably 270°C or higher, and more preferably 290°C or higher. If the heating temperature is in such a range, for example, when the melting point of the metal particles is 250°C, the heating temperature is considerably higher than the melting point of the metal particles, and the melting of the metal particles occurs surely and promptly, and a sintered body without voids can be obtained efficiently. When using a device equipped with a pressure vessel to pressurize the atmosphere in which the second laminate precursor exists, the heating temperature is preferably 300°C or lower. In the second process, when pressurizing the atmosphere in which the second laminate precursor exists, the pressure is preferably 0.101 MPa or more and 5.0 MPa or less, more preferably 0.15 MPa or more and 3.0 MPa or less, and even more preferably 0.5 MPa or more and 2.0 MPa or less. In the second process, when pressurizing the second laminate precursor by mechanical pressure means such as a flat press, the pressure is preferably 5 to 40 MPa. The time of the second process is preferably appropriately changed according to the composition and particle size of the metal particles, but is preferably 1 minute or more and 30 minutes or less, more preferably 1 minute or more and 15 minutes or less, and even more preferably 1 minute or more and 10 minutes or less.

[0129] The second step will be described with reference to FIG. 5. Note that the description of the same reference numerals may be omitted.

[0130] The second step is a step of pressurizing or depressurizing the atmosphere in which the laminate precursor 200 in which the first adherend 20, the second adherend 21, and the film-shaped sintering material 22 are laminated while heating the laminate precursor 200. As a result, the binder component 31 contained in the film-shaped sintering material 22 is decomposed and vaporized, and the metal particles 30 contained in the film-shaped sintering material 22 are melted and bonded to each other to form a sintered body 23. Then, the sintered body 23 joins the first adherend 20 and the second adherend 21, whereby a laminate 300 in which the first adherend 20, the sintered body 23, and the second adherend 21 are laminated in this order can be obtained.

[0131] Next, the second step when the second step includes a first process and a second process will be described with reference to FIG. 6. The first process is to pressurize the atmosphere in which the laminate precursor 200 is present while heating the laminate precursor 200 at a temperature equal to or higher than the resin decomposition start temperature included in the binder component and lower than the melting point of the metal particles. The first process performs heating and pressurization under relatively mild conditions. Therefore, melting of the metal particles 30 included in the film-shaped firing material 22 is suppressed. As a result, it is possible to progress the decomposition and vaporization of the binder component 31 while suppressing the melting of the metal particles 30 more efficiently. By performing the first process, the metal particles 30 are densely accumulated to form an aggregate 24 between the first adherend 20 and the second adherend 21. Thereby, a second laminate precursor 400 in which the first adherend 20, the aggregate 24, and the second adherend 21 are laminated in this order can be obtained. When the pressurizing means of the first process is by pressurizing the atmosphere in which the laminate precursor 400 is present, pressure can be applied to the laminate precursor 400 not only in the vertical direction but also in the horizontal direction and the like. Therefore, by compressing the film-shaped firing material 22 only in the direction parallel to the thickness direction, the possibility that the end portion of the film-shaped firing material 22 protrudes with respect to the first adherend 20 or the second adherend 21 can be reduced. Further, it is expected that the metal particles 30 in the film-shaped firing material 22 are more densely accumulated, and the possibility of obtaining a sintered body 23 with few voids by the subsequent second process is increased.

[0132] The second process is to heat the second laminate precursor 400 at a temperature equal to or higher than the melting point of the metal particles. As described above, the second laminate precursor 400 has an aggregate 24 formed by densely accumulating the metal particles 30. Therefore, even without performing a mechanical pressurization process, the metal particles 30 are in a state where they are easily melted and bonded to each other. As a result, even when heating the second laminate precursor 400 without pressurization or pressurizing the atmosphere in which the second laminate precursor 400 is present at a relatively low pressure, a sintered body 23 having good thermal conductivity is easily obtained. By joining the sintered body 23 to the first adherend 20 and the second adherend 21, a laminate 300 in which the first adherend 20, the sintered body 23, and the second adherend 21 are laminated in this order can be obtained.

[0133] (Optional process) In the method for manufacturing a laminate according to the present disclosure, mechanical pressure may be applied to the laminate before or after the second step, if necessary. Examples of the method for applying mechanical pressure to the laminate include a method using a flat press machine.

[0134] -Modification Example- In this example, in step (1-1), the film-shaped sintering material with a support sheet was attached to the back surface of the semiconductor wafer. However, in the method for manufacturing a semiconductor device according to the present disclosure, the film-shaped sintering material may be attached to the diced semiconductor element, and then steps (1-4) and (2-1) may be performed. In this case, it is preferable to manufacture the film-shaped sintering material in substantially the same shape as the semiconductor element in advance.

[0135] Through the above steps, a laminate is manufactured.

Description of Reference Numerals

[0136] 100a, 100b Film-shaped sintering material with a support sheet, 1 Film-shaped sintering material, 2 Support sheet, 3 Base film, 4 Adhesive layer, 5 Ring frame, 20 First adherend, 21 Second adherend, 22 Film-shaped sintering material, 23 Sintered body, 24 Aggregate, 30 Metal particles, 31 Binder component, 200 Laminate precursor, 300 Laminate, 400 Second laminate precursor

Claims

1. A first step of obtaining a laminate precursor by sandwiching a film-shaped firing material containing metal particles and a binder component between a first adherend and a second adherend; A second step of heating the laminate precursor and pressurizing the atmosphere in which the laminate precursor exists to decompose and vaporize the binder component; A method for manufacturing a laminate including the above.

2. The method for manufacturing a laminate according to Claim 1, wherein the pressure of the atmosphere is 0.15 MPa or more and 3.00 MPa or less.

3. The second step includes: a first treatment of obtaining a second laminate precursor by pressurizing the atmosphere while heating the laminate precursor at a temperature equal to or higher than the decomposition start temperature of the resin contained in the binder component and lower than the melting point of the metal particles; A second treatment of heating the second laminate precursor at a temperature equal to or higher than the melting point of the metal particles. The method for manufacturing a laminate according to Claim 1 or Claim 2.

4. The method for manufacturing a laminate according to any one of Claims 1 to 3, wherein the second step is a step performed in an autoclave.

5. The method for manufacturing a laminate according to any one of Claims 1 to 4, wherein the binder component contains a resin having a decomposition start temperature of 200°C or lower.

6. The method for manufacturing a laminate according to any one of Claims 1 to 5, wherein the binder component contains a thermoplastic resin, and the proportion of the content of the thermoplastic resin in the total amount of the binder component is 50% by mass or more.

7. The method for manufacturing a laminate according to any one of Claims 1 to 6, wherein the first adherend is a semiconductor element.

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