Film-shaped sintering material for heating and pressurization, and method for producing semiconductor device

Abstract

This film-shaped sintering material for heating and pressurization contains metal particles and a binder component that contains a resin having a decomposition initiation temperature of 200 °C or lower.

Description

Film-shaped sintered material for heating and pressurizing, and method for manufacturing semiconductor devices

[0001] The present disclosure relates to a film-shaped sintered material for heating and pressing, and a method for manufacturing a semiconductor device.

[0002] In recent years, the demand for semiconductor elements (e.g., power devices) mounted in automobiles, air conditioners, personal computers, etc. has increased with the trend toward higher voltages and currents. In applications such as power devices, semiconductor elements are prone to generate large amounts of heat due to their use under high voltages and currents. Therefore, it is necessary to efficiently dissipate the heat generated by the semiconductor elements.

[0003] Conventionally, a heat dissipation member (e.g., a heat sink) has been attached around a semiconductor element to dissipate heat generated by the semiconductor element to the outside. A film-shaped sintered material is sometimes used to bond the heat dissipation member to the semiconductor element. There is also a demand for the bonding material between the power semiconductor element and the substrate to be made of a metal with high thermal conductivity and heat resistance.

[0004] For example, Patent Document 1 proposes "a film-like sintered material containing sinterable metal particles and a binder component, wherein the temperature (A) at which the negative slope is greatest in a thermogravimetric curve (TG curve) measured at a heating rate of 10°C / min in a nitrogen atmosphere, and the maximum peak temperature (B) in a temperature range from 25°C to 400°C in a differential thermal analysis curve (DTA curve) measured at a heating rate of 10°C / min in a nitrogen atmosphere using alumina particles as a reference sample, satisfy the relationship A<B<A+60°C." Patent Document 2 proposes a method for manufacturing a bonded body, comprising: "Step A of preparing a laminate in which two objects to be bonded are temporarily bonded via a heat bonding sheet having a pre-sintering layer containing a heat-decomposable binder that is solid at 23°C; Step B of heating the laminate from a first temperature or lower to a second temperature defined below; and Step C of maintaining the temperature of the laminate within a predetermined range after Step B, wherein the laminate is pressurized during at least a portion of Step B and at least a portion of Step C. First temperature: a temperature at which an organic component contained in the pre-sintering layer is reduced by 10% by weight when thermogravimetric measurement of the pre-sintering layer is performed. When Steps B and C are performed in the atmosphere, the thermogravimetric measurement is performed in the atmosphere. When Steps B and C are performed in a nitrogen atmosphere, a reducing gas atmosphere, or a vacuum atmosphere, the thermogravimetric measurement is performed in a nitrogen atmosphere."

[0005] Patent Document 1: JP 2018-188723 A Patent Document 2: Japanese Patent No. 6796937 A

[0006] It is desirable to sinter such sintered materials for bonding under as mild a temperature as possible. In the examples of Patent Document 2, the sintered material is heated and pressurized at 200°C or 300°C for sintering. However, when the sintered material is sintered by heating and pressurizing, voids tend to form inside the sintered body. Furthermore, the presence of voids inside the sintered body can cause a decrease in thermal conductivity, a decrease in thickness uniformity, etc.

[0007] The problem to be solved by one embodiment of the present disclosure is to provide a film-shaped sintering material for heating and pressing that can produce a sintered body with few voids, and a method for manufacturing a semiconductor device that uses the film-shaped sintering material for heating and pressing according to the present disclosure.

[0008] The present disclosure includes the following embodiments. <1> A film-shaped sintered material for heating and pressing, comprising metal particles and a binder component containing a resin having a decomposition onset temperature of 200°C or less. <2> The film-shaped sintered material for heating and pressing according to <1>, wherein the resin having a decomposition onset temperature of 200°C or less is an aliphatic polycarbonate. <3> The film-shaped sintered material for heating and pressing according to <1> or <2>, wherein the resin having a decomposition onset temperature of 200°C or less is an aliphatic polycarbonate containing an organic acid group. <4> The film-shaped sintered material for heating and pressing according to any one of <1> to <3>, wherein the metal particles contain silver. <5> The film-shaped sintered material for heating and pressing according to any one of <1> to <4>, wherein the metal particles contain metal particles having a particle size of 100 nm or less. <6> The film-shaped sintered material for heating and pressing according to any one of <1> to <5>, wherein the film-shaped sintered material for heating and pressing is used to bond a semiconductor element to another component. <7> The film-shaped sintering material for heating and pressing according to <6>, wherein the semiconductor element is a power semiconductor element. <8> A method for manufacturing a semiconductor device using the film-shaped sintering material for heating and pressing according to <6> or <7>, comprising: a step of obtaining a laminate precursor by sandwiching the film-shaped sintering material for heating and pressing between the semiconductor element and the other component; and a step of heating and pressurizing the laminate precursor. <9> The method for manufacturing a semiconductor device according to <8>, wherein the step of heating and pressurizing the laminate precursor includes a first process of heating and pressurizing the laminate precursor at a temperature that is equal to or higher than the decomposition onset temperature of a resin having a decomposition onset temperature of 200°C or lower and lower than the melting point of the metal particles, thereby obtaining a second laminate precursor, and a second process of heating the second laminate precursor at a temperature that is equal to or higher than the melting point of the metal particles. <10> The method for manufacturing a semiconductor device according to <8>, wherein the step of heating and pressurizing the laminate precursor includes a first process of heating and pressurizing the laminate precursor at a temperature equal to or higher than the decomposition onset temperature of a resin having a decomposition onset temperature of 200°C or lower and lower than 250°C to obtain a second laminate precursor, and a second process of heating the second laminate precursor at a temperature of 250°C or higher.

[0009] According to one embodiment of the present disclosure, there is provided a film-shaped sintering material for heating and pressing, which can produce a sintered body with few voids. According to another embodiment of the present disclosure, there is provided a method for manufacturing a semiconductor device using the film-shaped sintering material for heating and pressing according to the present disclosure.

[0010] Fig. 1 is a schematic cross-sectional view showing an example of a flow for obtaining a sintered body from a film-shaped sintering material for heating and pressing according to the present disclosure; Fig. 2 is a schematic cross-sectional view of a film-shaped sintering material with a support sheet according to one embodiment of the present disclosure; Fig. 3 is a schematic cross-sectional view of a film-shaped sintering material with a support sheet according to another embodiment of the present disclosure; Fig. 4 is a schematic perspective view of a film-shaped sintering material with a support sheet according to another embodiment of the present disclosure; Fig. 5 is a schematic cross-sectional view showing an example of a flow for obtaining a sintered body from a conventional film-shaped sintering material;

[0011] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples are intended to illustrate the embodiments and do not limit the scope of the invention. In the numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value of that numerical range may be replaced with a value shown in an example. In this disclosure, the term "to" representing a numerical range indicates a range that includes the numerical values ​​described as the upper and lower limits, respectively. Furthermore, when only the upper limit value in a numerical range represented by "to" is specified in units, this means that the lower limit value is also specified in the same units. In this specification, "(meth)acrylic" includes both acrylic and methacrylic.

[0012] Each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition, if multiple substances corresponding to each component are present in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0013] <Film-shaped sintering material for heating and pressing> The film-shaped sintering material for heating and pressing according to the present disclosure contains metal particles and a binder component including a resin having a decomposition onset temperature of 200°C or less (hereinafter also referred to as "specific resin"). Here, the film-shaped sintering material for heating and pressing refers to a film-shaped material for obtaining a sintered body by heating and pressing (for example, at 100°C or more and 0.15 MPa or more).

[0014] The film-shaped sintering material for heating and pressing according to the present disclosure has the above-described configuration, which allows a sintered body with few voids to be obtained. The reason for this will be explained with reference to Fig. 5. Fig. 5 shows an example of the process for obtaining a sintered body from a conventional film-shaped sintering material.

[0015] As shown in FIG. 5 , a conventional film-shaped sintered material 10 includes metal particles 11 and a binder component 12 containing a resin whose decomposition onset temperature exceeds 200°C. Furthermore, when the conventional film-shaped sintered material 10 is heated, the binder component 12 decomposes and vaporizes, the metal particles 11 melt, and the metal particles bond together, ultimately forming a sintered body 14. Here, a high melting point of the metal particles 11 necessitates a high sintering temperature for the film-shaped sintered material 10, so a low melting point of the metal particles 11 is desirable. For example, metal particles 11 have a characteristic that their melting point gradually decreases as their size decreases to the nano-level (melting point depression). Therefore, selecting metal particles 11 with small sizes can result in metal particles 11 with a low melting point. In this case, the decomposition temperature of the resin contained in the binder component of the conventional film-shaped sintered material 10 exceeds 200°C, which can reduce the difference between the melting point of the metal particles 11 and the decomposition temperature of the resin. In this case, the decomposition of the binder component 12 and the melting of the metal particles 11 may proceed simultaneously. As a result, it is easy to form a sintered body precursor 13 in which the metal particles 11 melt and bond together around the binder component 12 before the sintered body 14 is formed in which most of the binder component 12 is decomposed. Furthermore, when the sintered body precursor 13 is formed, the metal particles 11 melt together and bond together, so the particle shape is not maintained and the melting point is elevated. Therefore, the sintered body 14 obtained by decomposing the binder component 12 in the sintered body precursor 13 may be incomplete, with voids 15 formed in the area where the binder component was previously present. Furthermore, it is difficult to remelt such an incomplete sintered body 14 to eliminate the voids 15 and aggregate the metals together due to the elevated melting point of the metals.

[0016] On the other hand, as shown in FIG. 1 , the film-shaped sintered material 20 for heating and pressing according to the present disclosure contains metal particles 21 and a binder component 22 containing a specific resin. The binder component 22 contains a specific resin. The decomposition onset temperature of the specific resin is 200°C or lower. Therefore, the difference between the melting point of the metal particles 21 and the decomposition temperature of the specific resin is large. Therefore, by applying heat and pressure, the decomposition and vaporization of the binder component 22 proceeds first. As a result, the metal particles 21 are densely aggregated, resulting in an aggregate 23 of metal particles. Further heating of the aggregate 23 causes the metal particles to melt and bond together, resulting in a sintered body 24. As described above, the film-shaped sintered material for heating and pressing according to the present disclosure produces an aggregate 23 in which the metal particles are densely aggregated, making it difficult for the metal particles to melt and bond together around the binder component. Furthermore, because the metal particles 21 contained in the aggregate 23 maintain their particle shape, the melting point of the metal particles 21 is less likely to rise above its initial value. Therefore, the metal particles 21 contained in the aggregate 23 are easily melted by heating, resulting in a sintered body 24 with few voids. Here, the film-shaped sintering material 20 for heating and pressing according to the present disclosure is heated and pressed to obtain the sintered body 24, thereby further promoting the decomposition and vaporization of the binder component 22. Furthermore, by heating and pressing, the voids contained in the aggregate 23 are more likely to disappear due to the pressure. In other words, if heating alone is not performed when sintering a film-shaped sintering material, voids will remain in the sintered body. For example, since the metal particles 21 are bonded together by heating, even if it is possible to increase the electrical conductivity of the sintered body, the voids will hinder the transfer of heat, making it difficult to obtain high thermal conductivity.

[0017] For these reasons, the film-shaped sintering material for heating and pressing according to the present disclosure is a film-shaped sintering material for heating and pressing that can produce a sintered body with few voids. Furthermore, the film-shaped sintering material for heating and pressing according to the present disclosure is suitable for producing a sintered body by heating and pressing (preferably at 100° C. or higher and 0.15 MPa or higher).

[0018] Hereinafter, each component contained in the film-shaped sintering material for heating and pressing according to the present disclosure will be described.

[0019] (Metal Particles) The film-shaped sintering material for heating and pressing according to the present disclosure contains metal particles. By including the metal particles, the metal particles melt and bond together when the film-shaped sintering material for heating and pressing is heated and pressed, resulting in a sintered body. By forming the sintered body, the adherend that was in contact with the film-shaped sintering material for heating and pressing is bonded.

[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; and barium titanate. From the viewpoint of easily adjusting the melting point of the metal particles so that they can be melted at a relatively low temperature, it is preferable that the metal particles contain silver. The silver content of 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 made of at least one type selected from the group consisting of silver and silver oxides.

[0021] To improve dispersibility in the binder component, the surfaces of the metal particles may be coated with an organic substance, such as an alcohol molecule derivative derived from an alcohol molecule having 1 to 12 carbon atoms, or an amine molecule derivative.

[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 either cubic or ellipsoidal.

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

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

[0025] The metal particles may include two or more types of metal particles with different particle sizes. Specifically, the metal particles may include metal particles with a particle size of 100 nm or less and metal particles with a particle size exceeding 100 nm. Here, metal particles with a particle size of 100 nm or less are referred to as "sinterable metal particles." Furthermore, metal particles with a particle size exceeding 100 nm are referred to as "non-sinterable metal particles." From the viewpoint of sintering the film-shaped sintered material for heating and pressing at a low temperature, it is preferable that at least some of the metal particles are sinterable metal particles with a large melting point depression. Furthermore, from the viewpoint of efficiently obtaining a sintered body by bonding the non-sinterable metal particles with the molten sinterable metal particles after sintering the film-shaped sintered material for heating and pressing, it is preferable that the metal particles include both sinterable 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 depending on the temperature at which the film-shaped sintered material for heating and pressing is sintered, and may be 0.1 nm to 100 nm, 0.3 nm to 50 nm, or 0.5 nm to 30 nm. The particle size of the non-sinterable metal particles may be greater than 150 nm and less than 50,000 nm, 150 nm to 10,000 nm, or 180 nm to 5,000 nm.

[0027] The particle size of the sinterable metal particles is measured in the same manner as the procedure for measuring the particle size of metal particles described above. Note that, in measuring the particle size of the sinterable metal particles, the selected metal particles are limited to those 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 above-described procedure for measuring the particle size of metal particles. Note that, in measuring the particle size of the non-sinterable metal particles, the selected metal particles are limited to those having a circle-equivalent diameter, which corresponds to the projected area, of more than 100 nm.

[0029] When the film-shaped sintered material for heating and pressing is used for joining semiconductor elements as described below, from the viewpoint of improving adhesion before sintering to the semiconductor element or other components while forming a sintered body with few voids, the content of metal particles (the total content of sinterable metal particles and non-sinterable metal particles; the same applies 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, even 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, based on the entire film-shaped sintered material for heating and pressing.

[0030] From the viewpoint that the film-shaped sintered material for heating and pressing contains a certain amount of metal particles with a large melting point depression so that a sintered body can be easily formed even at low sintering temperatures, 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, and more preferably 30% by mass or more and 95% by mass or less, of the total content of the metal particles.

[0031] (Binder Component) - Specific Resin - The binder component contains a resin (specific resin) whose decomposition onset temperature is 200°C or lower. Since the specific resin has a decomposition onset temperature of 200°C or lower, the difference between the melting point of the metal particles and the decomposition temperature of the specific resin is large. Therefore, by applying heat and pressure, the decomposition and vaporization of the binder component tends to proceed first.

[0032] The decomposition onset temperature of the resin is a value measured using a differential thermal thermogravimeter. Using a differential thermal-thermogravimetric simultaneous measurement device (e.g., Shimadzu Corporation, DTG-60), the temperature is raised from room temperature to 400°C at a heating rate of 20°C / min in a nitrogen atmosphere to measure the decomposition behavior. The decomposition onset temperature is the temperature at the intersection of a line parallel to the horizontal axis passing through the mass before the start of test heating and a tangent drawn so that the gradient between the bending points on the decomposition curve is maximized.

[0033] From the viewpoint of facilitating the production of a resin with a low decomposition onset temperature, the specific resin is preferably an aliphatic polycarbonate. An aliphatic polycarbonate is a polycarbonate whose main chain is composed of an aliphatic hydrocarbon group and a carbonate group (referring to a group represented by -O-CO-O- in this specification). The aliphatic polycarbonate may have a side chain. The main chain refers to the relatively longest bonding chain in the molecule of the compound. The side chain refers to a bonding chain branching from the main chain.

[0034] The aliphatic hydrocarbon group contained in the main chain preferably has 1 or more and 6 or less, more preferably 2 or more and 4 or less, and even more preferably 2 or 3 carbon atoms.

[0035] From the viewpoint of facilitating the production of a resin having a low decomposition onset temperature, 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 handleability, the organic acid group is preferably a carboxy group.

[0036] When the specific resin contains an organic acid group, the acidity derived from the organic acid group accelerates the decomposition of the specific resin, thereby lowering the decomposition initiation temperature.

[0037] 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) *-(CH ２ ) ｍ In formula (0), m represents an integer of 1 or more, and * represents a bond.

[0038] From the viewpoint of reducing the influence of the side chains 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 even more preferably 1 or 2.

[0039] More specifically, the aliphatic polycarbonate containing an organic acid group preferably contains a structural unit represented by the following formula (1).

[0040]

[0041] 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.

[0042] In formula (1), 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 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, and an n-decyl group. 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, and a halogen atom.

[0043] In formula (1), the number of carbon atoms in the aryl group is 6 to 20, and preferably 6 to 14. Examples of the aryl group include a phenyl group, an indenyl group, a naphthyl group, and a tetrahydronaphthyl group. The aryl group may be substituted with a substituent such as 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, or a tert-butyl group; another aryl group such as a phenyl group or 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, or a halogen atom.

[0044] From the viewpoint of adjusting the number of organic acid groups present in the molecule, the aliphatic polycarbonate containing organic acid groups preferably contains a structural unit represented by the following formula (2) in addition to the structural unit represented by the above formula (1).

[0045]

[0046] In formula (2), R ４ , R ５ and R ６are 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, an ether bond-containing group, an ester bond-containing group, or an allyl group.

[0047] In formula (2), the alkyl group has 1 to 10 carbon atoms, 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, and an n-decyl group. The alkyl group may be substituted with, for example, 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.

[0048] In formula (2), the number of carbon atoms in the aryl group is 6 to 20, and preferably 6 to 14. Examples of the aryl group include a phenyl group, an indenyl group, a naphthyl group, and a tetrahydronaphthyl group. The aryl group may be substituted with a substituent such as 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, or a tert-butyl group; another aryl group such as a phenyl group or 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, or a halogen atom.

[0049] In formula (2), X represents 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, and more preferably a hydrogen atom or a methyl group.

[0050] 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 a methyl group, an ethyl group, and an n-propyl group.

[0051] The number of carbon atoms in the haloalkyl group is 1 to 10, and preferably 1 to 4. Examples of the haloalkyl group include a fluoromethyl group, a chloromethyl group, a bromomethyl group, and an iodomethyl group.

[0052] The ether bond-containing group is preferably 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, and examples thereof include a methoxymethyl group, an ethoxymethyl group, and an allyloxymethyl group.

[0053] The ester bond-containing group is preferably an acyloxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms substituted with a benzyloxycarboxy group, or the like, and examples thereof include an acetoxymethyl group and a butylyloxymethyl group.

[0054] The content of the structural unit represented by 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, even 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, from the viewpoint of easily lowering the decomposition onset temperature of the aliphatic polycarbonate. From the viewpoint of reducing the influence of acid on articles to which the film-shaped sintered material for heating and pressing according to the present disclosure is applied, such as semiconductor elements, the content of the structural unit represented by 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, from the viewpoint of reducing the influence of acid on articles to which the film-shaped sintered material for heating and pressing according to the present disclosure is applied.

[0055] The content of the structural unit represented by 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, of all the structural units constituting the aliphatic polycarbonate.

[0056] 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 viewpoint of easily maintaining the film shape of the film-shaped fired material for heating and pressing according to the present disclosure and adjusting the viscosity of the film-forming composition.

[0057] The weight-average molecular weight of an aliphatic polycarbonate is a value measured by gel permeation chromatography (GPC). The weight-average molecular weight of an aliphatic polycarbonate is measured as follows. A chloroform solution with a concentration of 0.5% by mass of the aliphatic polycarbonate is prepared and measured using GPC. After the measurement, the weight-average molecular weight is calculated by comparing with that of polystyrene whose weight-average molecular weight is known and measured under the same conditions. The measurement conditions are as follows: Column: GPC column (Shodex K-804L, trade name of Showa Denko K.K.) Column temperature: 40°C Eluent: chloroform Flow rate: 1.0 mL / min

[0058] Specific examples of the aliphatic polycarbonate include those represented by the formula (1) １ , R ２ , R ３ , and n, respectively, R １ , R ２ , and R ３ are all hydrogen atoms, n is 1, and R ４ , R ５ , R ６ , and X, respectively, R ４ , R ５ , and R ６ are all hydrogen atoms, X is a methyl group, and the structural units include only those represented by formula (1) and those represented by formula (2).

[0059] When such an aliphatic polycarbonate is synthesized by adjusting the content of the structural unit represented by formula (1) in the aliphatic polycarbonate within the range of 1.0 mol % to 20 mol % of all the structural units constituting the aliphatic polycarbonate, it is possible to achieve a mass loss rate (described below) within a predetermined range and a decomposition onset temperature of 200° C. or lower. For example, even when the content of the structural unit represented by formula (1) in the aliphatic polycarbonate is as low as 3.0 mol % by mass or lower of all the structural units constituting the aliphatic polycarbonate, an aliphatic polycarbonate having a mass loss rate of about 95% by mass and a decomposition onset temperature of about 150° C. can be obtained.

[0060] From the viewpoint of facilitating a decrease in the decomposition initiation temperature of the aliphatic polycarbonate, specifically, the aliphatic polycarbonate is preferably a compound represented by the following formula (3).

[0061]

[0062] In formula (3), m and l represent the content (unit: mol %) of the structural unit relative to the total number of structural units constituting the aliphatic polycarbonate.

[0063] The decomposition starting temperature of the aliphatic polycarbonate is preferably 80°C or higher and 185°C or lower, more preferably 100°C or higher and 170°C or lower, and even more preferably 120°C or higher and 160°C or lower, from the viewpoint of preventing decomposition of the binder component before heating and from the viewpoint of obtaining a sintered body with few voids.

[0064] Since the decomposition initiation temperature of the aliphatic polycarbonate is low, it is preferable that most of the weight of the aliphatic polycarbonate is lost by decomposition when heated for a certain period of time, even at a low temperature. Therefore, the mass loss rate after holding at 160°C for 1 hour in thermogravimetric analysis is preferably 90% or more, more preferably 95% or more. From the viewpoint of preventing decomposition of the binder component before heating, the mass loss 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. The decomposition initiation temperature can be adjusted by the content of the structural unit represented by formula (1).

[0065] The mass loss rate is measured using a thermogravimetric analyzer. Examples of thermogravimetric analyzers that can be used include a DTG-60, a simultaneous differential thermal and thermogravimetric analyzer manufactured by Shimadzu Corporation. A sample is added to the thermogravimetric analyzer, 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. The sample is then held at that temperature for one hour to measure its thermal decomposition behavior. The mass loss rate is calculated by reading the mass (W1) after one hour of heating from the decomposition curve and calculating the ratio to the initial mass (W0) [i.e., (W0-W1) / W0×100].

[0066] The decomposition initiation temperature of the aliphatic polycarbonate is measured as described above.

[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 even more preferably 15°C or higher and 30°C or lower, from the viewpoints of the strength of the film-shaped sintered material for heating and pressing and the flexibility of the film-shaped sintered material for heating and pressing.

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

[0069] From the viewpoint of obtaining a sintered body with few voids, the content of the specific resin relative to the total binder components 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 even more preferably 80% by mass or more and 100% by mass or less.

[0070] -Other Resins- The binder component may contain a resin other than the specific resin. Examples of the resin other than the specific resin include an acrylic resin, polylactic acid, and a cellulose derivative. The content of the resin other than the specific resin relative to the entire binder component is, for example, preferably 0% by mass or more and 50% by mass or less, more preferably 0% by mass or more and 30% by mass or less, even more preferably 0% by mass or more and 20% by mass or less, and particularly preferably 0% by mass.

[0071] -Binder component content- From the viewpoint of obtaining a sintered body with few voids, 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, even more preferably 5% by mass or more and 20% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less, based on the entire film-shaped sintered material for heating and pressing.

[0072] (Other Components) The film-shaped sintered material for heating and pressing according to the present disclosure may contain other components in addition to the metal particles and binder component, such as a solvent, a dispersant, a plasticizer, a tackifier, a storage stabilizer, an antifoaming agent, a thermal decomposition accelerator, and an antioxidant.

[0073] (Thickness of film-shaped sintered material for heating and pressing) The thickness of the film-shaped sintered material for heating and pressing according to the present disclosure 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 even more preferably 30 μm or more and 90 μm or less.

[0074] The thickness of the film-shaped sintered material for heating and pressing is measured in accordance with JIS K7130 (1999). According to JIS K7130 (1999), the thickness is measured at any five points on the object, and the arithmetic mean value of the obtained values ​​is taken as the thickness of the film-shaped sintered material for heating and pressing. A constant pressure thickness gauge can be used as the thickness gauge.

[0075] (Method for producing a film-shaped sintered material for heating and pressing) The method for producing the film-shaped sintered material for heating and pressing is not particularly limited, and can be obtained by appropriately mixing metal particles, a binder component, and, if necessary, other components to obtain a mixture (hereinafter, the mixture is also referred to as a "raw material mixture"), and molding the mixture into a film. The molding can be performed, for example, by applying the raw material mixture onto a substrate to form a film, and then separating it from the substrate.

[0076] From the viewpoint of improving film-forming properties, the raw material mixture preferably contains a solvent. As the solvent, for example, one having a boiling point of less than 200°C is preferable. Examples of the solvent include n-hexane (boiling point: 68°C), ethyl acetate (boiling point: 77°C), 2-butanone (boiling point: 80°C), n-heptane (boiling point: 98°C), methylcyclohexane (boiling point: 101°C), toluene (boiling point: 111°C), acetylacetone (boiling point: 138°C), n-xylene (boiling point: 139°C), and dimethylformamide (boiling point: 153°C). These may be used alone or in combination.

[0077] Examples of methods for applying the raw material mixture include methods using various coaters such as an air knife coater, blade coater, bar coater, gravure coater, comma coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Mayer bar coater, and kiss coater.

[0078] When the raw material mixture contains a solvent, it is preferable to heat-dry the raw material mixture in the form of a film after applying the raw material mixture to the film. The temperature during the heat-drying is preferably equal to or lower than the decomposition starting temperature of the specific resin contained in the binder component and equal to or higher than the boiling point of the solvent contained in the film-shaped raw material mixture. The heat-drying time is not particularly limited, and is preferably, for example, 10 seconds to 10 minutes.

[0079] The film-shaped sintered material for heating and pressing according to the present disclosure is used, for example, to bond two adherends together to obtain a laminate. Examples of the adherends to be bonded include semiconductor wafers, semiconductor elements, substrates, lead frames, and heat dissipators (heat sinks, etc.).

[0080] The film-shaped sintering material for heat and pressure application according to the present disclosure is preferably used for bonding semiconductor elements to other components. Examples of other components bonded to semiconductor elements using the film-shaped sintering material for heat and pressure application according to the present disclosure include substrates. Furthermore, the other components may also be semiconductor elements, and the film-shaped sintering material for heat and pressure application according to the present disclosure may be used to bond two semiconductor elements together. In particular, the semiconductor elements to be bonded are preferably power semiconductor elements. Power semiconductor elements have a rated current of 1 A or more. The film-shaped sintering material for heat and pressure application according to the present disclosure produces sintered bodies with few voids. Therefore, sintered bodies obtained by sintering the film-shaped sintering material for heat and pressure application according to the present disclosure have high thermal conductivity. This enables more efficient dissipation of heat generated by semiconductor elements. A technology known as the die-top system is also known for power semiconductors. In this technology, a copper foil having a special shape is attached to a die (chip) via a sintering paste. Specifically, the copper foil may be generally rectangular but have a notch on one side. In this case, the first adherend is a semiconductor element, and the second adherend is copper foil.

[0081] (Method for Producing Laminate) Hereinafter, an example of a method for producing a laminate using the film-shaped sintering material for heating and pressing according to the present disclosure will be described.

[0082] A laminate can be produced by joining two adherends using the film-shaped sintered material for heating and pressing according to the present disclosure. Any method can be used to produce a laminate, as long as two adherends can be joined via the film-shaped sintered material for heating and pressing according to the present disclosure. For example, it is also suitable to produce a laminate by the laminate production method described below. The laminate production method preferably includes: a step (1) of obtaining a laminate precursor by sandwiching the film-shaped sintered material for heating and pressing between a first adherend and a second adherend; and a step (2) of heating and pressurizing the laminate precursor.

[0083] (Step (1)) Step (1) is a step of obtaining a laminate precursor by sandwiching a film-shaped sintered material for heating and pressing between a first adherend and a second adherend. The method of sandwiching the film-shaped sintered material for heating and pressing between the first adherend and the second adherend is, for example, as follows: Attach one side of the film-shaped sintered material for heating and pressing to the surface of the first adherend. Then, attach the second adherend to one side of the film-shaped sintered material for heating and pressing so that it faces the first adherend via the film-shaped sintered material for heating and pressing.

[0084] (Step (2)) Step (2) is a step of heating and pressurizing the laminate precursor. The heating temperature is preferably 150°C or higher and 600°C or lower, more preferably 165°C or higher and 500°C or lower, and even more preferably 180°C or higher and 400°C or lower. The pressure is preferably 0.15 MPa or higher and 50 MPa or lower. When this step is performed 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 second treatment described below, the heating and pressurizing time is, for example, preferably 5 seconds to 180 minutes, more preferably 5 seconds to 150 minutes, and even more preferably 10 seconds to 120 minutes.

[0085] The step (2) may be carried out by applying heat and pressure simultaneously, or by applying heat and pressure sequentially, but it is preferable to apply heat and pressure simultaneously.

[0086] The apparatus applicable to step (2) is not particularly limited as long as it is an apparatus capable of applying heat and pressure to the laminate precursor. Examples of the apparatus include a platen press, a flip-chip bonder, a die bonder, an autoclave, etc., and it is preferable to use a platen press or an autoclave that can apply strong pressure.

[0087] Mechanical pressure means (plate press) can require a large-scale apparatus. From the viewpoint of reducing the frequency of use of mechanical pressure means, it is preferable to use an autoclave as the apparatus in step (2).

[0088] The procedure for using an autoclave in step (2) is, for example, as follows: First, the laminate precursor is placed in the autoclave. At this time, the method for placing the laminate precursor is not particularly limited, but for example, a method of placing a horizontal table in the autoclave and placing the laminate precursor on it can be mentioned.

[0089] The autoclave is then sealed and heated and pressurized. The heating method is not particularly limited, and may be performed using a heating device attached to the autoclave, or by using an autoclave equipped with a jacket (a steam passage) and flowing steam through the jacket.

[0090] The method of pressurization is not particularly limited, and examples thereof include a method of pressurizing by supplying a gas into the autoclave. The gas is not particularly limited, and examples thereof include nitrogen, air, etc.

[0091] Step (2) may be performed under two different heating and pressurizing conditions. For example, step (2) preferably includes a first step of heating and pressurizing the laminate precursor at a temperature equal to or higher than the decomposition starting temperature of the specific resin and lower than the melting point of the metal particles to obtain a second laminate precursor, and a second step of heating the second laminate precursor at a temperature equal to or higher than the melting point of the metal particles.

[0092] -First Treatment- In the first treatment, the laminate precursor is heated and pressurized at a temperature equal to or higher than the decomposition onset temperature of the specific resin and lower than the melting point of the metal particles to obtain a second laminate precursor. Here, the melting point of the metal particles in step (2) refers to the maximum peak temperature in the temperature range of 25°C to 400°C in a differential thermal analysis curve (DTA curve) measured for the film-like fired material at a heating rate of 10°C / min in a nitrogen atmosphere using alumina particles as a reference sample. Specifically, the differential thermal analysis is performed on the film-like fired material using a thermal analysis measuring device (e.g., a thermal analyzer TG / DTA simultaneous measuring device DTG-60, manufactured by Shimadzu Corporation) at a heating rate of 10°C / min in a nitrogen atmosphere using approximately the same amount of alumina particles as the measurement sample as a reference sample.

[0093] The first treatment involves heating and pressurizing at a temperature below the melting point of the metal particles, which allows the decomposition and vaporization of the binder component to proceed while suppressing melting of the metal particles contained in the film-shaped fired material for heating and pressurizing.

[0094] In the first treatment, the heating temperature is preferably at least 15°C higher than the decomposition onset temperature of the specific resin, more preferably at least 30°C higher than the decomposition onset temperature of the specific resin. For example, the heating temperature can be 150°C or higher, preferably 165°C or higher, and more preferably 180°C or higher. If the heating temperature is within this range, for example, when the decomposition onset temperature of the specific resin is 150°C, the heating temperature can be higher than the decomposition temperature of the specific resin. The upper limit of the heating temperature is preferably no higher than 20°C lower than the melting point of the metal particles, and more preferably no higher than 40°C lower than the melting point of the metal particles. For example, in the first treatment, the heating temperature can be less than 250°C, preferably no higher than 230°C, and more preferably no higher than 210°C. If the heating temperature is within this range, for example, when the melting point of the metal particles is 250°C, the heating temperature can be lower than the melting point of the metal particles. Since the decomposition onset temperature of the specific resin is 200°C or less, it is easy to set the heating temperature of the first treatment to a value far from both the decomposition onset temperature of the specific resin and the melting point of the metal particles. As an example, when the decomposition onset temperature of the specific resin is 150°C and the melting point of the metal particles is 250°C, the first treatment can be performed at a heating temperature of 200°C. As described above, the pressure applied to the laminate precursor may be in the range of 0.15 MPa to 50 MPa. However, when the pressurization method is an autoclave, the pressure is preferably 0.50 MPa to 3.00 MPa, more preferably 1.00 MPa to 3.00 MPa, and even more preferably 1.50 MPa to 3.00 MPa. In the first treatment, the laminate precursor is heated and pressurized, eliminating voids generated by the decomposition of the binder component, and an aggregate in which the metal particles are densely accumulated in the second laminate precursor can be obtained. Therefore, a sintered body with few voids can be obtained by the subsequent second treatment. The time for the first treatment is preferably changed appropriately depending on the composition of the binder component and the metal particles, and is, for example, preferably 5 seconds to 180 minutes, more preferably 5 seconds to 150 minutes, and even more preferably 10 seconds to 120 minutes.

[0095] In the second treatment, the second laminate precursor is heated to a temperature equal to or higher than the melting point of the metal particles. From the viewpoint of obtaining a sintered body with fewer voids, it is preferable to pressurize the second laminate precursor in the second treatment as well.

[0096] By performing the second treatment, the metal particles melt and bond together, resulting in a sintered body. Because the binder component is decomposed and vaporized through the first treatment, the metal particles are densely packed together after the first treatment. Therefore, the metal particles are easily melted and bonded together without the need for physical pressure treatment. As a result, a sintered body can be obtained by heating the second laminate precursor and setting the atmospheric pressure to the conditions described above in the second treatment.

[0097] In the second treatment, the heating temperature is preferably 600°C or lower, more preferably 500°C or lower, and even more preferably 400°C or lower. The lower limit of the heating temperature is preferably 20°C higher than the melting point of the metal particles, and more preferably 40°C higher than the melting point of the metal particles. For example, in the second treatment, 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 within this range, for example, when the melting point of the metal particles is 250°C, the heating temperature is higher than the melting point of the metal particles, and the metal particles melt reliably and quickly, resulting in an efficient sintered body without voids. As an example, when the decomposition onset temperature of the specific resin is 150°C and the melting point of the metal particles is 250°C, the second treatment can be performed at 350°C. As described above, the pressure when pressurizing the second laminate precursor may be set to a value in the range of 0.15 MPa to 50 MPa, but when pressurization is performed using an autoclave, the pressure is more preferably 0.15 MPa to 3.0 MPa, and even more preferably 0.5 MPa to 2.0 MPa. The time for the second treatment is preferably changed appropriately depending on the composition and particle size of the metal particles, but is, for example, preferably 1 minute to 30 minutes, more preferably 1 minute to 15 minutes, and even more preferably 1 minute to 10 minutes.

[0098] It is preferable that the laminate is manufactured through the above steps.

[0099] <Film-shaped sintered material with support sheet> An example of an embodiment of a film-shaped sintered material for heating and pressing according to the present disclosure is a film-shaped sintered material with a support sheet, which has a support sheet and a film-shaped sintered material for heating and pressing provided on the support sheet.

[0100] In the film-shaped sintered material with a support sheet according to the present disclosure, the support sheet preferably has a base film and a pressure-sensitive adhesive layer provided on the base film.

[0101] According to the film-shaped sintered material with a support sheet of the present disclosure, a first adherend is adhered to the surface of the film-shaped sintered material for heating and pressing of the film-shaped sintered material with a support sheet, thereby obtaining a laminate of the first adherend and the film-shaped sintered material with a support sheet. The support sheet is then peeled off from the laminate, and the exposed surface of the film-shaped sintered material for heating and pressing (i.e., the surface of the film-shaped sintered material for heating and pressing that faced the support sheet) is adhered to the second adherend. This results in a laminate in which the first adherend, the film-shaped sintered material for heating and pressing, and the second adherend are stacked in this order. The film-shaped sintered material with a support sheet of the present disclosure is preferably used as a dicing sheet used to obtain semiconductor elements by cutting a semiconductor wafer into multiple chips (hereinafter also referred to as "dicing").

[0102] The film-shaped sintered material with a support sheet will be described with reference to Figures 2 and 3. However, the film-shaped sintered material with a support sheet according to the present disclosure is not limited to this.

[0103] 2 and 3 are schematic cross-sectional views of film-shaped materials for firing with a support sheet. Each of the film-shaped materials for firing with a support sheet 100a and 100b comprises a film-shaped material for firing for heating and pressurizing 1 and a support sheet 2.

[0104] As shown in Figures 2 and 3, the support sheet 2 preferably has a base film 3 and an adhesive layer 4. The adhesive layer 4 facilitates laminating the film-shaped sintered material for heating and pressurizing onto the support sheet, facilitates dicing as described below, and also serves to secure the ring frame 5. Note that the ring frame 5 is placed on the support sheet-attached film-shaped sintered materials 100a, 100b to secure the support sheet-attached film-shaped sintered materials 100a, 100b during dicing of the semiconductor wafer, but is not a component constituting the support sheet-attached film-shaped sintered materials 100a, 100b. The adhesive layer 4 may be present on the entire surface of the base film 3 as shown in Figure 2, or may be present along the outer periphery of the base film 3 as shown in Figure 3.

[0105] Figure 4 shows a schematic perspective view of a film-shaped sintered material with a support sheet 100b. As shown in Figure 4, the film-shaped sintered material with a support sheet 100b may be circular to fit the shape of a semiconductor wafer. Although a schematic perspective view of the film-shaped sintered material with a support sheet 100a is not shown, it may also be circular to fit the shape of a semiconductor wafer.

[0106] Each component of the film-shaped sintered material with a support sheet will be described in detail below, and reference numerals will be omitted.

[0107] (Support sheet) The support sheet is not particularly limited as long as it can provide a film-like sintered material for heating and pressing on the support sheet. The support sheet may have only a base film, or may have a 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-like sintered material for heating and pressing and facilitating dicing, it is preferable that the support sheet has a base film and an adhesive layer provided on the base film.

[0108] -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-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyurethane film, ionomer, etc. Furthermore, 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.

[0109] When the support sheet does not have a pressure-sensitive adhesive layer, the surface of the substrate film may be treated with a release agent. Examples of the release agent include alkyd-based release agents, silicone-based release agents, fluorine-based release agents, unsaturated polyester-based release agents, polyolefin-based release agents, and wax-based release agents. From the viewpoint of heat resistance, the release agent is preferably at least one selected from the group consisting of alkyd-based release agents, silicone-based release agents, and fluorine-based release agents.

[0110] The thickness of the substrate film is not particularly limited, and 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 substrate film within the above numerical range, the substrate film is less likely to tear even when cut by dicing. In addition, since the film-shaped sintered material with support sheet is given sufficient flexibility, it exhibits good adhesion to the adherend (e.g., semiconductor wafer, etc.).

[0111] The shape of the substrate film is preferably adjusted appropriately according to the shape of the adherend. For example, when the adherend is a semiconductor wafer, the shape of the film-shaped sintered material for heating and pressing is preferably circular. When the shape of the substrate film is circular, the diameter is preferably 10 mm or more and 500 mm or less.

[0112] The substrate film may be one type of substrate film or a laminate of two or more types of substrate films.

[0113] - Adhesive Layer - The adhesive layer is a layer having adhesiveness capable of fixing the film-shaped sintered material on the support sheet. Furthermore, for example, when the film-shaped sintered material with support sheet is used as a dicing sheet, the adhesive layer in the present disclosure can fix a device (e.g., a ring frame) that fixes the film-shaped sintered material with support sheet during dicing. It is preferable that the adhesive layer allows the ring frame to be peeled off after dicing.

[0114] Examples of materials for the adhesive layer include 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, the adhesive layer can be formed from an adhesive with an uneven surface, an energy ray-curable adhesive, an adhesive containing a thermal expansion component, etc.

[0115] The adhesive strength of the adhesive layer to a 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, from the viewpoint of the peelability of the film-like sintered material for heating and pressing.

[0116] The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is, for example, preferably from 1 μm to 100 μm, more preferably from 2 μm to 80 μm, and even more preferably from 3 μm to 50 μm.

[0117] The pressure-sensitive adhesive layer may be disposed over the entire surface of the base film or may be disposed on a part of the base film. When disposed on a part of the base film, the pressure-sensitive adhesive layer is preferably disposed along the contour of the shape of the base film in a plan view.

[0118] When the pressure-sensitive adhesive layer is disposed over the entire surface of the base film, the shape of the pressure-sensitive adhesive layer is the same as the shape of the base film. When the pressure-sensitive adhesive layer is disposed over only a portion of the base film, the shape of the pressure-sensitive adhesive layer is preferably ring-shaped.

[0119] (Film-shaped firing material for heating and pressing) The film-shaped firing material for heating and pressing contained in the film-shaped firing material with support sheet is the film-shaped firing material for heating and pressing according to the present disclosure, and the preferred aspects of the composition and thickness are as described above.

[0120] The shape of the film-shaped sintered material for heating and pressing is not particularly limited, but may be a sheet or a long film, and a long film-shaped sintered material for heating and pressing is preferably a wound roll. Furthermore, from the viewpoint of reducing the amount of relatively expensive metal particles discarded, it is preferable to appropriately adjust the shape of the film-shaped sintered material for heating and pressing to match the shape of the adherend. For example, when the adherend is a semiconductor wafer, the shape of the film-shaped sintered material for heating and pressing is preferably circular. When the shape of the film-shaped sintered material for heating and pressing is circular, it is preferable that the diameter be 10 mm or more and 500 mm or less.

[0121] (Other Components) The film-shaped sintered material with a support sheet according to the present disclosure may have other components in addition to the support sheet and the film-shaped sintered material for heating and pressing. Examples of other components include a protective sheet. The protective sheet is a sheet that prevents the surface of the film-shaped sintered material and the pressure-sensitive adhesive layer from contacting the outside until the film-shaped sintered material with a support sheet is used. Examples of protective sheets include, but are not limited to, sheets made of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, etc.

[0122] -Method for producing a film-shaped sintered material with a support sheet- There are no particular limitations on the method for producing a film-shaped sintered material with a support sheet, as long as it is possible to sequentially laminate a support sheet and a film-shaped sintered material for heating and pressing. Below, an example of a method for producing a film-shaped sintered material with a support sheet is shown, but the method is not limited to this.

[0123] --Specific Example 1 of a Method for Producing a Film-Like Sintered Material with a Support Sheet-- A method for producing a film-like sintered material with a support sheet 100a will be described, in which a base film 3, an adhesive layer 4, and a film-like sintered material for heating and pressurizing 1 are laminated in this order as shown in Figure 2. Note that reference numerals will be omitted below.

[0124] A mixture containing the materials and solvent constituting the film-shaped sintered material for heating and pressing (hereinafter also referred to as "sintered material raw material mixture") is applied (e.g., coated) in the form of a film onto a protective sheet (or other member), and the film-shaped sintered material raw material mixture is heated and dried as needed to form a film-shaped sintered material for heating and pressing on the protective sheet. Meanwhile, a mixture containing the materials and solvent constituting the adhesive layer (hereinafter also referred to as "adhesive layer raw material mixture") is applied (e.g., coated) in the form of a film onto a substrate film, and the film-shaped adhesive layer raw material mixture is heated and dried as needed to form an adhesive layer on the substrate film. Then, the exposed surface of the film-shaped sintered material for heating and pressing formed on the protective sheet and the exposed surface of the adhesive layer formed on the substrate film are bonded together to obtain a film-shaped sintered material with a support sheet.

[0125] --Specific Example 2 of a Method for Producing a Film-Like Sintered Material with a Support Sheet-- As shown in Figure 3, a method for producing a film-like sintered material with a support sheet 100b will be described, which has a substrate film 3 on which an adhesive layer 4 is formed along the outer periphery of the substrate film 3, and a film-like sintered material for heating and pressurizing 1 inside the adhesive layer 4. Note that reference numerals will be omitted below.

[0126] The adhesive layer raw material mixture is applied (e.g., coated) onto a protective sheet (or other member) so as to form a shape that follows the periphery of the base film. Then, the sintered material raw material mixture is applied (e.g., coated) in the form of a film inside the area on the protective sheet (or other member) where the adhesive layer raw material mixture has been applied (e.g., coated). Then, if necessary, the sintered material raw material mixture and adhesive layer raw material mixture applied (e.g., coated) onto the protective sheet are heated and dried to form an adhesive layer and a film-like sintered material for heating and pressing on the base film. Then, the exposed surfaces of the adhesive layer and film-like sintered material for heating and pressing formed on the protective sheet are bonded to the base film, thereby obtaining a film-like sintered material with a support sheet.

[0127] (Uses of film-shaped sintered material with support sheet) Uses of film-shaped sintered material with support sheet include, for example, as described above, a bonding material for bonding semiconductor elements to other parts (adherends), and further, a film-shaped sintered material with support sheet that also serves as a dicing sheet.

[0128] (Method for manufacturing a semiconductor device) A method for manufacturing a semiconductor device using a film-shaped sintered material for heating and pressing will be described. In the following description of the method for manufacturing a semiconductor device, the term "semiconductor device" refers to a laminate including an adherend (described below), a sintered body obtained by sintering the film-shaped sintered material for heating and pressing, and a semiconductor element. The term "semiconductor element" refers to a chip obtained by dicing a semiconductor wafer.

[0129] The method for manufacturing a semiconductor device using the film-shaped sintering material for heating and pressing preferably includes a step of obtaining a laminate precursor by sandwiching the film-shaped sintering material for heating and pressing between a semiconductor element and another component, and a step of applying heat and pressure to the laminate precursor.

[0130] In the method for manufacturing a semiconductor device using a film-shaped sintered material for heating and pressing, the step of heating and pressurizing the laminate precursor preferably includes a first process in which the laminate precursor is heated and pressurized at a temperature equal to or higher than the decomposition onset temperature of the resin, which has a decomposition onset temperature of 200°C or lower, and lower than the melting point of the metal particles, to obtain a second laminate precursor, and a second process in which the second laminate precursor is heated at a temperature equal to or higher than the melting point of the metal particles.

[0131] As an example of a method for using the film-shaped sintering material for heating and pressing, a method for manufacturing a semiconductor device using the film-shaped sintering material with a support sheet that also serves as a dicing sheet will be described.

[0132] A method for manufacturing a semiconductor device using a film-like sintered material with a support sheet (for example, 100a in FIG. 2 or 100b in FIG. 3) includes the following steps: a step (1-1) of attaching the film-like sintered material with a support sheet (for example, 100a in FIG. 2 or 100b in FIG. 3) to the backside of a semiconductor wafer (hereinafter simply referred to as "semiconductor wafer") having a circuit formed on its surface (front side); a step (1-2) of dicing the semiconductor wafer to obtain a semiconductor element; a step (1-3) of peeling off the semiconductor element, the film-like sintered material for heating and pressing (for example, reference numeral 1 in FIG. 2 or 3) and the support sheet (for example, reference numeral 2 in FIG. 2 or 3) to obtain an element with the film-like sintered material; and a step (1-4) of attaching the element with the film-like sintered material to the surface of an adherend. and step (2-1) of firing a film-shaped fired material for heating and pressing (e.g., reference numeral 1 in FIG. 2 or 3) to bond the semiconductor element and the adherend. Steps (1-1) to (1-4) correspond to step (1) in the above-described method for producing a laminate, and step (2-1) corresponds to step (2) in the above-described method for producing a laminate.

[0133] Step (1-1) Step (1-1) is a step of attaching a film-shaped sintering material with a support sheet to the back surface of a semiconductor wafer. The film-shaped sintering material for heating and pressurizing, which is included in the film-shaped sintering material with a support sheet, is attached to the back surface of the semiconductor wafer so that it adheres to the back surface of the semiconductor wafer. In this way, a laminate A is obtained in which the support sheet, the film-shaped sintering material for heating and pressurizing, and the semiconductor wafer are stacked in this order.

[0134] The diameter of the semiconductor wafer is not particularly limited, but is preferably smaller than the inner diameter of the ring frame (e.g., reference numeral 5 in Figure 2 or Figure 3). Examples of semiconductor wafers include silicon wafers; compound semiconductor wafers such as silicon carbide, gallium arsenide, and gallium nitride. When using a semiconductor device as a power semiconductor, the semiconductor wafer may be a silicon wafer if it operates at relatively low temperatures. However, if operation at higher temperatures is envisioned, the semiconductor wafer is preferably a compound semiconductor wafer, and silicon carbide or gallium nitride is preferred as the compound semiconductor. It is preferable that a circuit be pre-formed on the surface of the semiconductor wafer. The formation of a circuit on the semiconductor wafer can be carried out by conventionally commonly used methods such as etching and lift-off. It is preferable that the surface opposite the circuit surface (back surface) of the semiconductor wafer be pre-ground. The grinding method is not particularly limited, and examples include known means using a grinder, etc.

[0135] -Step (1-2)- Step (1-2) is a step of dicing the semiconductor wafer to obtain semiconductor elements. More specifically, this is a step of dicing the laminate A for each circuit formed on the semiconductor wafer surface to obtain a laminate B in which a support sheet, a film-shaped sintering material for heating and pressing, and a semiconductor element are stacked in this order. Dicing is preferably performed so as to cut both the semiconductor wafer and the film-shaped sintering material for heating and pressing. The dicing cut depth may completely cut the film-shaped sintering material for heating and pressing, but is preferably set to halfway through the layer of the film-shaped sintering material for heating and pressing. The dicing method is not particularly limited, and examples include a method in which the peripheral portion of the support sheet (the outer periphery of the support) is fixed with a ring frame (e.g., reference numeral 5 in Figure 2 or Figure 3) and then the wafer is singulated with a rotating circular blade such as a dicing blade. The means for cutting the semiconductor wafer is not limited to using a cutting blade, and laser dicing, dicing by plasma treatment, etc. can also be performed. Laser dicing may be a dicing method in which a modified region that serves as a fracture initiation point is formed in the semiconductor wafer by a laser, and the semiconductor wafer is fractured at the modified region by a mechanical action such as expanding a support sheet.

[0136] -Step (1-3)- Step (1-3) is a step of peeling the semiconductor chip and the film-like sintering material for heating and pressing from the support sheet to obtain an element with the film-like sintering material. The method for peeling the semiconductor element and the film-like sintering material for heating and pressing from the support sheet is not particularly limited, and examples include a method using a collet or the like. By peeling the semiconductor element and the film-like sintering material for heating and pressing from the support sheet, a laminate C (element with film-like sintering material) is obtained in which the film-like sintering material for heating and pressing and the semiconductor element are stacked in this order.

[0137] Step (1-4) Step (1-4) is a step of attaching an element with a film-like sintering material to the surface of an adherend. Specifically, this is a step of attaching the element with a film-like sintering material to the surface of an adherend by contacting the surface of the adherend with the surface of the film-like sintering material-attached chip having the film-like sintering material for heating and pressurizing. This step results in a laminate D in which the adherend, the film-like sintering material for heating and pressurizing, and the semiconductor element are stacked in this order.

[0138] The adherend is not particularly limited, but examples thereof include a substrate, another semiconductor element, a lead frame, a heat sink, a heat pipe, etc., made of a metal plate such as a copper plate, can also be used as the heat sink.

[0139] Step (2-1) Step (2-1) is a step of firing the film-shaped firing material for heating and pressing to bond the semiconductor element and the adherend. By firing the film-shaped firing material for heating and pressing, the binder components contained in the film-shaped firing material for heating and pressing are decomposed and vaporized, and the metal particles are melted to form a sintered body. Then, the sintered body bonds the semiconductor element and the adherend, thereby obtaining a semiconductor device.

[0140] The conditions for firing the film-shaped fired material for heating and pressing may be the conditions described in step (2) of the method for producing a laminate, and the first and second treatments may be performed in this step (2-1).

[0141] While in this example, a film-shaped sintering material with a support sheet is attached to the backside of the semiconductor wafer in step (1-1), the method for manufacturing a semiconductor device according to the present disclosure may also involve attaching a film-shaped sintering material for heating and pressing to a diced semiconductor element, followed by steps (1-4) and (2-1). In this case, it is preferable to previously manufacture the film-shaped sintering material for heating and pressing to have substantially the same shape as the semiconductor element.

[0142] 100a, 100b Film-shaped sintered material with support sheet, 1 Film-shaped sintered material for heating and pressing, 2 Support sheet, 3 Base film, 4 Adhesive layer, 5 Ring frame, 10 Film-shaped sintered material, 11 Metal particles, 12 Binder component, 13 Sintered body precursor, 14 Sintered body, 15 Voids, 20 Film-shaped sintered material for heating and pressing, 21 Metal particles, 22 Binder component, 23 Aggregate, 24 Sintered body

[0143] The disclosure of Japanese Patent Application No. 2022-061105, filed on March 31, 2022, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A metal particle having a particle size of 100 nm or less, A binder component including a resin having a decomposition starting temperature of 200° C. or less; A film-like sintered material for heating and pressing, which is used for joining a semiconductor element to another component, comprising:

2. 2. The film-shaped sintered material for heating and pressing according to claim 1, wherein the resin having a decomposition starting temperature of 200[deg.] C. or lower is an aliphatic polycarbonate.

3. 3. The film-shaped sintered material for heating and pressing according to claim 1, wherein the resin having a decomposition starting temperature of 200° C. or lower is an aliphatic polycarbonate containing an organic acid group.

4. The film-shaped sintering material for heating and pressing according to claim 1 , wherein the metal particles contain silver.

5. 2. The film-shaped sintered material for heating and pressing according to claim 1, wherein the semiconductor element is a power semiconductor element.

6. A method for manufacturing a semiconductor device using the film-shaped sintering material for heating and pressing according to claim 1 or 5, comprising the steps of: obtaining a laminate precursor by sandwiching the film-shaped sintering material for heating and pressing between the semiconductor element and the other component; and heating and pressing the laminate precursor.

7. 7. The method for manufacturing a semiconductor device according to claim 6, wherein the step of heating and pressurizing the laminate precursor includes a first process of heating and pressurizing the laminate precursor at a temperature equal to or higher than the decomposition onset temperature of a resin having a decomposition onset temperature of 200° C. or lower and lower than the melting point of the metal particles to obtain a second laminate precursor, and a second process of heating the second laminate precursor at a temperature equal to or higher than the melting point of the metal particles.

8. 7. The method for manufacturing a semiconductor device according to claim 6, wherein the step of heating and pressurizing the laminate precursor comprises a first process of heating and pressurizing the laminate precursor at a temperature equal to or higher than the decomposition onset temperature of a resin having a decomposition onset temperature of 200° C. or lower and lower than 250° C. to obtain a second laminate precursor, and a second process of heating the second laminate precursor at a temperature of 250° C. or higher.