Method of manufacturing semiconductor device

Abstract

A method of manufacturing a semiconductor device includes: a step of forming a temporary crimped body by heating and pressurizing a laminate having a first circuit member, a second circuit member, and a thermosetting adhesive layer by a pressing member; and a step in which the temporary crimped body is heated in a pressurized atmosphere to form a connected body. The first circuit component may be a semiconductor chip. The laminate is pressurized by a pressing member at a predetermined pressure of 1.50 MPa or less. At least one of the pressing members is heated so as to be at a temporary pressure bonding temperature equal to or higher than the initial temperature of the thermosetting adhesive layer in a part or all of the heating and pressing periods of the laminate by the pressing members.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor device. Background Art

[0002] In the manufacture of semiconductor devices, a flip chip connection method is sometimes used in which a conductive protrusion called a bump is provided on a semiconductor chip or a wiring circuit board as a connection portion, and the semiconductor chip is connected to the wiring circuit board or other semiconductor chip via an adhesive by connecting the connection portions to each other. For example, Patent Document 1 discloses a method of manufacturing a semiconductor device by a flip chip connection method including the following steps: a step of obtaining a temporary crimping body in which semiconductor chips are temporarily crimped to each other; and a step of bonding the connection portions to each other by pressurizing and heating the temporary crimping body.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2018 / 194156 Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] When manufacturing a semiconductor device by a method including connecting a connection portion of a semiconductor chip or semiconductor wafer to a connection portion of another semiconductor chip or the like by metal bonding, a portion of the connection portion may collapse and deform significantly during the connection. Such significant deformation of the connection portion may cause a decrease in connection reliability.

[0008] The present invention relates to a technology for ensuring good conduction and suppressing deformation of a connection portion caused by connection when manufacturing a semiconductor device by a method including connecting a connection portion of a semiconductor chip or a semiconductor wafer to a connection portion of another semiconductor chip or the like by metal bonding.

[0009] Means for solving technical problems

[0010] The present invention includes the following. [1]

[0012] A method for manufacturing a semiconductor device, comprising:

[0013] A process of heating and pressurizing a laminate having a first circuit component having a first connecting portion comprising a first metal material, a second circuit component having a second connecting portion comprising a second metal material, and a thermosetting adhesive layer with the thermosetting adhesive layer interposed between the first circuit component and the second circuit component by a pair of opposing pressing components, thereby forming a temporary crimped body in which the first connecting portion is in contact with the second connecting portion; and

[0014] The method further comprises the step of heating the temporary crimping body to a predetermined final crimping temperature under a pressurized atmosphere to form a connecting body in which the first connecting portion and the second connecting portion are electrically connected through metal bonding between the first metal material and the second metal material.

[0015] The first circuit component is a semiconductor chip or a semiconductor wafer, and the second circuit component is a wiring circuit substrate, a semiconductor chip or a semiconductor wafer.

[0016] The stack is pressurized by the pair of pressing members at a predetermined pressure of 1.50 MPa or less,

[0017] During a part or the whole of the period during which the stacked body is heated and pressurized by the pair of pressing members, at least one of the pair of pressing members is heated to a predetermined temporary pressing temperature, wherein the temporary pressing temperature is a temperature that is not less than the starting temperature of the thermosetting adhesive layer and is lower than the formal pressing temperature,

[0018] The onset temperature is the onset temperature of a heat generation peak showing a maximum heat generation amount in a DSC curve obtained by differential scanning calorimetry under the condition that the sample of the thermosetting adhesive layer is heated at a heating rate of 10° C. / min.

[0019] The main compression bonding temperature is a temperature higher than or equal to at least one of a melting point of the first metal material or a melting point of the second metal material in the pressurized atmosphere. [2]

[0021] The method according to [1], wherein:

[0022] The predetermined pressure is not less than 0.94 MPa and not more than 1.50 MPa. [3]

[0024] The method according to [1] or [2], wherein:

[0025] The temporary compression bonding temperature is equal to or higher than the starting temperature and equal to or lower than 200° C. [4]

[0027] The method according to any one of [1] to [3], wherein

[0028] The time for which the stacked body is heated and pressurized by the pair of pressing members is 5 seconds or less. [5]

[0030] The method according to any one of [1] to [4], wherein

[0031] The thermosetting adhesive layer exhibits a shear viscosity of 10000 Pa·s or less at a temperature 20° C. lower than the starting temperature, the shear viscosity being a value measured under conditions of a heating rate of 10° C. / min, a frequency of 10 Hz, and a strain of 1%. [6]

[0033] The method according to any one of [1] to [5], wherein

[0034] The time for heating the temporarily pressed body to a temperature equal to or higher than at least one of a melting point of the first metal material or a melting point of the second metal material in the pressurized atmosphere is 60 seconds or less. [7]

[0036] The method according to any one of [1] to [6], wherein

[0037] The pressure of the pressurized atmosphere exceeds the atmospheric pressure and is 0.90 MPa or less. [8]

[0039] The method according to any one of [1] to [7], wherein

[0040] The thermosetting adhesive layer comprises:

[0041] Thermosetting resins having a molecular weight of less than 10,000;

[0042] A curing agent for the thermosetting resin; and a polymer component having a weight average molecular weight of more than 10,000. [9]

[0044] The method according to [8], wherein:

[0045] The glass transition temperature of the polymer component is 200° C. or lower.

[10]

[0047] The method according to any one of [1] to [9], wherein

[0048] The thermosetting resin layer exhibits a shear viscosity of 10000 Pa·s or more at 40°C.

[0049] Effects of the Invention

[0050] When a semiconductor device is manufactured by a method including connecting a connection portion of a semiconductor chip to a connection portion of another semiconductor chip or the like by metal bonding, deformation of the connection portion caused by the connection can be suppressed, and good conduction between the connection portions can be easily ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The present invention is a process diagram showing an example of a method for manufacturing a semiconductor device.

[0052] Figure 2 The present invention is a process diagram showing an example of a method for manufacturing a semiconductor device.

[0053] Figure 3 The present invention is a process diagram showing an example of a method for manufacturing a semiconductor device.

[0054] Figure 4 This is a schematic diagram showing a method for obtaining the onset temperature from a DSC curve.

[0055] Figure 5 This is a cross-sectional view of a connection portion in a connector.

[0056] Figure 6 This is a cross-sectional view of a connection portion in a connector.

[0057] Figure 7 This is a cross-sectional view of a connection portion in a connector.

[0058] Figure 8 This is a cross-sectional view of a connection portion in a connector. DETAILED DESCRIPTION

[0059] The present invention is not limited to the following examples.

[0060] Figure 1 , Figure 2 and Figure 3 The present invention is a process diagram showing an example of a method for manufacturing a semiconductor device. Figures 1 to 3The method shown includes: a process of preparing a laminate 100, the laminate 100 having a first circuit component 1 having a first connection portion 15 including a first metal material, a second circuit component 2 having a second connection portion 25 including a second metal material, and a thermosetting adhesive layer 3; heating and pressurizing the laminate 100 by a pair of opposing pressing components 41, 42, thereby forming a temporary crimping body 101 in which the first connection portion 15 and the second connection portion 25 are in contact; and heating the temporary crimping body 101 to a formal crimping temperature under a pressurized atmosphere, thereby forming a connection body 102 (semiconductor device) in which the first connection portion 15 and the second connection portion 25 are electrically connected through metal bonding between the first metal material and the second metal material. The first circuit component 1 can be a semiconductor chip or a semiconductor wafer. The second circuit component 2 can be a wiring circuit substrate, a semiconductor chip or a semiconductor wafer.

[0061] like Figure 1 As shown, the stacked body 100 is prepared, for example, by a method including the following steps: a step of preparing a first circuit component 1 (for example, a semiconductor chip) having a plate-shaped main body 10 and a plurality of first connecting portions 15 arranged on a main surface of the main body 10; a step of providing a thermosetting adhesive layer 3 on the surface of the first circuit component 1 on the side of the first connecting portion 15; a step of preparing a second circuit component 2 having a plate-shaped main body 20 and a second connecting portion 25 arranged on the main surface of the main body 20; and a step of arranging the first circuit component 1 on the second circuit component 2 in such a manner that the thermosetting adhesive layer 3 is interposed between the first circuit component 1 and the second circuit component 2, and the first connecting portion 15 and the second connecting portion 25 are arranged opposite to each other.

[0062] The main body 10 of the first circuit component 1 (semiconductor chip or semiconductor wafer) is not particularly limited and can include various semiconductor substrates and integrated circuits. The main body 10 can include, for example, elemental semiconductors composed of the same element such as silicon and germanium, or compound semiconductors such as gallium arsenide and indium phosphide.

[0063] The first connection portion 15 of the first circuit component 1 has a metal column 11 and a bump 12 provided on the metal column 11. The first metal material is contained in the bump 12, which is a portion joined to the second connection portion 25. The metal column 11 may be, for example, a copper column. The melting point of the first metal material contained in the bump 12 may be greater than 220° C. and less than 330° C. or greater than 140° C. and less than 220° C. The bump 12 may be a solder bump containing a solder as the first metal material. The first metal material may be a solder containing a Sn-Ag alloy, a Sn-Pb alloy, a Sn-Bi alloy, a Sn-Cu alloy, or a Sn-Ag-Cu alloy.

[0064] The wiring circuit substrate as the second circuit component 2 has, for example, an insulating substrate as a main body 20 and wiring including a second connection portion 25 provided on the insulating substrate. The insulating substrate may be, for example, a glass epoxy substrate, a polyimide resin substrate, a polyester resin substrate, or a ceramic substrate. Similar to the first circuit component 1, the semiconductor chip as the second circuit component 2 may have a semiconductor substrate and an integrated circuit. The semiconductor wafer as the second circuit component 2 may include a plurality of parts corresponding to the semiconductor chip.

[0065] The second connection portion 25 of the second circuit component 2 may be, for example, a metal pad containing a second metal material. The second metal material may be, for example, gold, silver, copper, solder, tin, nickel, or a combination thereof. The solder as the second metal material may include Sn-Ag alloy, Sn-Pb alloy, Sn-Bi alloy, Sn-Cu alloy, or Sn-Ag-Cu alloy.

[0066] The thermosetting adhesive layer 3 is a layer formed by a thermosetting adhesive, and is provided on the first circuit component 1, for example, by attaching a pre-formed film-like thermosetting adhesive to the first circuit component 1. The film-like thermosetting adhesive can be attached to the first circuit component 1, for example, by hot pressing, roller lamination, or vacuum lamination. The area and thickness of the film-like thermosetting adhesive are appropriately set according to the size of the first circuit component 1, the height of the first connecting portion 15, etc. The thickness of the film-like thermosetting adhesive and the thermosetting adhesive layer 3 can be, for example, not less than 1 μm and not more than 60 μm. It is also possible to singulate a semiconductor wafer to which a film-like thermosetting adhesive is attached by dicing, thereby preparing a semiconductor chip to which a thermosetting adhesive layer 3 is attached as the first circuit component 1. The details of the thermosetting adhesive layer 3 and the thermosetting adhesive forming the thermosetting adhesive layer 3 will be described later.

[0067] like Figure 2 As shown in the figure, a pair of pressing members 41 and 42 are arranged opposite to each other, and the laminate 100 is sandwiched between the pressing member 41 arranged on the second circuit component 2 side and the pressing member 42 arranged on the first circuit component 1 side, thereby heating and pressurizing. Through the temporary pressing process including the heating and pressurizing, the temporary pressing body 101 is formed. During a part or all of the period during which the laminate 100 is heated and pressurized by the pressing members 41 and 42, the pressing member 41, the pressing member 42, or both of them are heated in a manner to reach a predetermined temporary pressing temperature.

[0068] The stack 100 is heated by heat transfer from the pressing member in contact with the stack 100. For example, the pressing member 41 disposed on the side of the second circuit component 2 may be a workbench, and the pressing member 42 on the side of the first circuit component 1 may be a crimping head. The first circuit component 1 may also be adsorbed on the pressing member 42 as a crimping head, and the connection parts may be aligned with each other by moving the crimping head. Therefore, for example, a crimping machine such as a flip chip bonding machine having a crimping head may be used. The stack 100 may also be formed by arranging the first circuit component 1 adsorbed on the pressing member 42 as a crimping head and the thermosetting adhesive layer 3 on the second circuit component 2, and directly pressurizing the stack 100 using the crimping head (pressing member 42).

[0069] The temporary pressure-bonding temperature is a certain temperature set within a range above the starting temperature of the thermosetting adhesive layer 3. The starting temperature here is the starting temperature of the exothermic peak showing the maximum heat generation in the DSC curve obtained by differential scanning calorimetry under the condition that a part of the thermosetting adhesive layer 3, i.e., the sample, is heated at a heating rate of 10°C / min. Figure 4 This is a schematic diagram showing a method for obtaining the onset temperature from a DSC curve. Figure 4 The DSC curve shown includes a baseline L0 and an exothermic peak P caused by the curing reaction of the thermosetting adhesive layer 3 observed in the middle of the baseline L0 in the temperature range of 60 to 280°C. The temperature T of the intersection of the extended line L1 of the baseline L0 in the lower part of the exothermic peak P and the tangent line L2 of the DSC curve at the point where the DSC curve on the low temperature side of the temperature showing the maximum maximum value of the exothermic peak P shows the maximum inclination is the starting temperature. In addition to the maximum peak showing the maximum maximum value, the exothermic peak may include one or more shoulder peaks. In the case where the exothermic peak includes one or more shoulder peaks located on the temperature side than the temperature showing the maximum maximum value, the temperature of the intersection of the tangent line of the DSC curve at the point where the DSC curve on the low temperature side of the shoulder peak on the lowest temperature side shows the maximum inclination and the extended line of the baseline of the DSC curve is set as the starting temperature.

[0070] If the temporary crimping temperature is above the starting temperature, the viscosity of the thermosetting adhesive layer 3 is greatly reduced during the heating and pressurizing for forming the temporary crimping body, so the thermosetting adhesive layer 3 is easily removed from between the first connecting portion 15 and the second connecting portion 25. Therefore, even if the heating and pressurizing conditions in the formal crimping process for forming the connecting body 102 from the temporary crimping body 101 are relatively mild, it is easy to ensure good conduction. As a result, the deformation of the connecting portion (e.g., the bump 12) in the connecting body 102 can be suppressed.

[0071] From the above viewpoints, the temporary pressing temperature may be 1°C, 2°C, 3°C, 4°C or 5°C higher than the starting temperature. The temporary pressing temperature may be 200°C or lower, 195°C or lower, 190°C or lower or 185°C or lower. The temporary pressing temperature is usually a temperature lower than the melting point of the first metal material and the melting point of the second metal material.

[0072] The starting temperature of the thermosetting adhesive layer 3 may be, for example, 140° C. to 190° C. The starting temperature of the thermosetting adhesive layer 3 may be 145° C. to 150° C. or 155° C., or 185° C. to 180° C., 175° C. to 170° C. or 165° C.

[0073] During the heating and pressurization of the laminate 100 by the pressing members 41 and 42, the temperature (heating temperature) of the pressing members 41, 42, or both of them may be substantially maintained at a certain temporary pressing temperature above the starting temperature, or may be changed. However, even when the heating temperature is substantially maintained at a certain temporary pressing temperature, the actual heating temperature may be changed within a certain range (for example, the temporary pressing temperature ±1°C). When the heating temperature changes, the maximum temperature is set to be the specified temporary pressing temperature.

[0074] When the time (temporary pressing time) during which the laminate 100 is heated and pressed by the pressing members 41 and 42 is appropriately short, the curing reaction of the thermosetting adhesive layer 3 tends to be difficult to proceed excessively in the stage before heating at the formal pressing temperature. Therefore, the temporary pressing time may be 5 seconds or less, 4 seconds or less, 3 seconds or less, or 2 seconds or less, or may be 0.5 seconds or more, or 1 second or more.

[0075] In order to form the temporary crimping body 101, a prescribed pressure is applied to the stack 100 by pressing components 41 and 42. When the pressure is appropriately small, the gaps and the thermosetting adhesive layer 3 are fully eliminated from the connection parts, and the deformation of the connection parts is easily suppressed. From this point of view, the prescribed pressure for forming the temporary crimping body 101 can be less than 1.50MPa, or it can be more than 0.94MPa and less than 1.50MPa. Pressurization under pressure within this range can also be beneficial in avoiding the reduction of connection reliability caused by damage to the connection part. From the same point of view, the prescribed pressure for forming the temporary crimping body 101 can be less than 1.45MPa, less than 1.40MPa or less than 1.35MPa, or it can be more than 1.0MPa, more than 1.05MPa or more than 1.1Ma. In order to form the temporary crimping body 101, the load applied to the stack 100 as a whole by pressing components 41 and 42 can be more than 50N and less than 80N.

[0076] An additional thermosetting adhesive layer and an additional circuit component (e.g., a semiconductor chip) may be further provided on the side of the first circuit component 1 opposite to the second circuit component 2. In this case, the circuit components may be stacked in sequence by a temporary pressing process, or a temporary pressing body may be formed by a temporary pressing process of heating and pressurizing a stacked body having three or more circuit components. When stacking three or more circuit components, a semiconductor chip having a TSV structure may be used as a circuit component.

[0077] Then, if Figure 3 As shown in (a), the temporary crimping body 101 is formed into a connector 102 through a formal crimping process in which the connector 102 is heated to a predetermined formal crimping temperature under a pressurized atmosphere in a heating furnace 50. The formal crimping temperature for forming the connector 102 is set in a range above the temperature of at least one of the melting point of the first metal material or the melting point of the second metal material. By heating the temporary crimping body 101 at a heating temperature reaching the formal crimping temperature above the temperature of at least one of the melting point of the first metal material or the melting point of the second metal material, a metal bond between the first metal material and the second metal material is formed. For example, in the formal crimping process, the bump 12 of the first connector 15 melts, and the deformed bump 12 is interposed between the metal column 11 and the second connector 25, thereby electrically connecting the first connector 15 to the second connector 25.

[0078] The curing reaction of the thermosetting adhesive layer 3 is also carried out by heating in the main pressing step, forming a cured thermosetting adhesive, that is, an adhesive layer 3A. For example, the connection body 102 can be a semiconductor device including a semiconductor chip as a first circuit component 1, a second circuit component 2, and an adhesive layer 3A. After the main pressing step, the connection body 102 can be further heated to further promote the curing reaction of the thermosetting adhesive.

[0079] The heating furnace 50 may be, for example, a pressurized reflow furnace or a pressurized oven. The gas forming the pressurized atmosphere in the heating furnace 50 may include air, nitrogen, or formic acid.

[0080] The heating temperature of the temporary crimping body 101 in the main crimping process may be constant or variable, but the temporary crimping body 101 is heated so that the highest temperature becomes the main crimping temperature. The heating temperature here may be the temperature of the pressurized atmosphere.

[0081] The final crimping temperature may be, for example, 220° C. or higher and 330° C. or lower. When the final crimping temperature is within this range, it is easy to suppress the scattering of the connection portion and the formation of voids in the connection portion due to excessive alloy growth accompanying metal bonding, and to form a good metal bond. This tendency is significant, for example, when the first metal material or the second metal material is solder.

[0082] In the formal crimping process, the time for which the temporary crimping body 101 is heated to a temperature above the melting point of the first metal material or the melting point of the second metal material can be less than 60 seconds. Alternatively, in the formal crimping process, the time for which the temporary crimping body 101 is heated to a temperature above 220°C can be less than 60 seconds. According to the formal crimping process under this condition, it is easy to suppress the scattering of the connection part and the formation of voids in the connection part caused by excessive alloy growth accompanying metal bonding, and form a good metal bond. In the formal crimping process, the time for which the temporary crimping body 101 is heated to a temperature above the melting point of the first metal material or the melting point of the second metal material can be more than 5 seconds. In the formal crimping process, the time for which the temporary crimping body 101 is heated to a temperature above 220°C can be more than 5 seconds.

[0083] Before the temporary crimping body 101 is heated to the formal crimping temperature, it can be heated at a certain preheating temperature lower than the melting point of the first metal material and the melting point of the second metal material in a pressurized atmosphere. Heating at this preheating temperature can help suppress the voids in the connection portion. The time for which the temporary crimping body 101 is heated at a certain preheating temperature can be more than 1 minute or more than 2 minutes, or less than 20 minutes or less than 15 minutes. The preheating temperature can be higher than the temporary crimping temperature, and can be more than 160°C, more than 165°C, or more than 170°C. The preheating temperature can be less than 200°C, less than 195°C, less than 190°C, less than 185°C, or less than 180°C.

[0084] The pressure of the pressurized atmosphere in the heating furnace 50 is appropriately set according to the size and number of the circuit components. The pressure of the pressurized atmosphere can be, for example, higher than the atmospheric pressure and lower than 1 MPa. A higher pressure can, for example, help suppress voids and improve connectivity. A lower pressure can help suppress rounded corners. From these viewpoints, the pressure of the pressurized atmosphere can be, for example, higher than the atmospheric pressure and lower than 0.90 MPa or higher than 0.20 MPa and lower than 0.80 MPa.

[0085] A plurality of temporary crimped bodies can be heated at once in one heating furnace 50. The pressurized atmosphere allows the plurality of temporary crimped bodies to be pressurized with high uniformity. When the temporary crimped bodies are heated in the pressurized atmosphere, there is a tendency to suppress the adhesive layer overflowing from the outer periphery of the connection body, i.e., the generation of fillets, compared with the case where the temporary crimped bodies are heated and pressurized using a pressing member.

[0086] The thermosetting adhesive layer 3 and the thermosetting adhesive forming the thermosetting adhesive layer 3 will be described in detail below.

[0087] The thermosetting adhesive layer 3 may be a layer formed of a thermosetting adhesive containing a thermosetting resin having a molecular weight of less than 10,000, a curing agent for the thermosetting resin, and a polymer component having a weight average molecular weight of 10,000 or more.

[0088] Thermosetting resin is a compound that forms a cross-linked polymer by a curing reaction, and its example includes epoxy resin. Epoxy resin can be a compound having more than two epoxy groups. Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin and dicyclopentadiene type epoxy resin. These can be used alone or in combination of more than two kinds. The weight average molecular weight of epoxy resin is usually less than 10000. In this specification, weight average molecular weight refers to the standard polystyrene conversion value measured by gel permeation chromatography (GPC).

[0089] The content of the epoxy resin may be 5% to 75% by mass, 10% to 50% by mass, or 15% to 35% by mass, based on the mass of the thermosetting adhesive layer 3 or the total mass of components other than the solvent in the thermosetting adhesive.

[0090] The curing agent is a component that causes the curing reaction of the thermosetting resin to proceed. When the thermosetting resin is an epoxy resin, examples of the curing agent include phenolic resin curing agents, acid anhydride curing agents, amine curing agents, imidazole curing agents, and phosphine curing agents. The curing agent may include one or more selected from phenolic resin curing agents, acid anhydride curing agents, amine curing agents, and imidazole curing agents, and may also include imidazole curing agents.

[0091] The phenolic resin curing agent is a compound having two or more phenolic hydroxyl groups, and examples thereof include phenol novolac, cresol novolac, phenol aralkyl resin, cresol naphthol formaldehyde polycondensate, triphenylmethane type polyfunctional phenol and other polyfunctional phenolic resins. These can be used alone or in combination of two or more.

[0092] From the viewpoint of good curability, adhesion and storage stability, the equivalent ratio (phenolic hydroxyl group / epoxy group, molar ratio) of the phenolic resin curing agent to the epoxy resin may be 0.3 to 1.5, 0.4 to 1.0 or 0.5 to 1.0.

[0093] Examples of the acid anhydride curing agent include methylcyclohexanetetracarboxylic dianhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, and ethylene glycol trimellitic anhydride. These can be used alone or in combination of two or more.

[0094] From the viewpoint of good curability, adhesion and storage stability, the equivalent ratio (anhydride group / epoxy group, molar ratio) of the acid anhydride curing agent to the epoxy resin may be 0.3 to 1.5, 0.4 to 1.0 or 0.5 to 1.0.

[0095] The amine curing agent is a compound having an amino group, and examples thereof include dicyandiamide.

[0096] From the viewpoint of good curability, adhesion and storage stability, the equivalent ratio (amine / epoxy group, molar ratio) of the amine curing agent to the epoxy resin may be 0.3 to 1.5, 0.4 to 1.0 or 0.5 to 1.0.

[0097] The imidazole curing agent is an imidazole derivative, and examples thereof include 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, Amino-6-[2'-undecylimidazole-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole cyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole and adducts of epoxy resins and imidazoles. From the viewpoint of excellent curability, storage stability and connection reliability, an imidazole curing agent can be selected from 1-cyanoethyl-2-undecyl imidazole, 1-cyano-2-phenyl imidazole, 1-cyanoethyl-2-undecyl imidazole trimellitate, 1-cyanoethyl-2-phenyl imidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenyl imidazole cyanuric acid adduct, 2-phenyl-4,5-dihydroxymethyl imidazole and 2-phenyl-4-methyl-5-hydroxymethyl imidazole. These can be used alone or in combination of two or more. Microcapsules containing them can also be used as latent curing agents.

[0098] The content of the imidazole curing agent may be 0.1 to 20 parts by mass, 0.1 to 10 parts by mass, or 3.2 to 5.5 parts by mass relative to 100 parts by mass of the epoxy resin.

[0099] Examples of the phosphine-based curing agent include triphenylphosphine, tetraphenylphosphine tetraphenylboron, tetraphenylboron tetra(4-methylphenyl)borate, and tetraphenylboron (4-fluorophenyl)borate.

[0100] The content of the phosphine-based curing agent may be 0.1 to 10 parts by mass or 0.1 to 5 parts by mass relative to 100 parts by mass of the epoxy resin.

[0101] The polymer component can contribute to the heat resistance and film formation of the thermosetting adhesive layer. Examples of polymer components include phenoxy resins, polyimide resins, polyamide resins, polycarbodiimide resins, cyanate resins, acrylic resins, polyester resins, polyethylene resins, polyethersulfone resins, polyetherimide resins, polyvinyl butyral resins, polyurethane resins and acrylate rubbers. The polymer component can be a copolymer comprising a partial structure corresponding to a resin or rubber selected from them. From the viewpoint of heat resistance and film formation, the polymer component can include one or more selected from phenoxy resins, polyimide resins, acrylate rubbers, cyanate resins and polycarbodiimide resins. The polymer component can include one or more selected from phenoxy resins, polyimide resins and acrylate rubbers. These polymer components can be used alone or in combination of two or more. In this specification, the polymer component is a component different from the above-mentioned thermosetting resin (e.g., epoxy resin).

[0102] From the perspective of the adhesion of the film-like thermosetting adhesive to the circuit components, the glass transition temperature (Tg) of the polymer component can be below 200°C, above 50°C and below 200°C, above 50°C and below 180°C, or above 50°C and below 150°C. When the Tg of the polymer component is above 50°C, there is a tendency for the adhesion (viscosity) of the thermosetting adhesive to be appropriately weakened. When the Tg of the polymer component is below 200°C, there is a tendency for the thermosetting adhesive to be easily and appropriately embedded in the unevenness of the connection part based on the circuit component, and as a result, the effect of void suppression tends to be relatively large. Tg here refers to the value measured using DSC (manufactured by PerkinElmer Japan Co., Ltd., DSC-Pyirs1) under the conditions of a sample amount of 10 mg, a heating rate of 10°C / min, and an air atmosphere.

[0103] The weight average molecular weight of the polymer component may be 30,000 or more, 40,000 or more, or 50,000 or more, or 200,000 or less.

[0104] The ratio Ca / Cd (mass ratio) of the content Ca of the epoxy resin to the content Cd of the polymer component can be 0.01 to 5, 0.05 to 3, or 0.1 to 2. If the ratio Ca / Cd is 0.01 or more, better curability and adhesion are easily obtained. When the ratio Ca / Cd is 5 or less, better film formation is easily obtained.

[0105] The thermosetting adhesive layer 3 and the thermosetting adhesive may contain a flux. The flux may be, for example, a compound having a group represented by formula (1). The flux may be a single compound or a combination of two or more compounds represented by formula (1).

[0106]

[0107] In formula (1), R 1 represents an electron donating group. Examples of electron donating groups include alkyl, hydroxyl, amino, alkoxy and alkylamino. The electron donating group may be alkyl, hydroxyl or alkoxy, or may be alkyl.

[0108] R 1 The alkyl group may have 1 to 10 carbon atoms or 1 to 5 carbon atoms. The alkyl group may be linear or branched, or linear. When the alkyl group is linear, the number of carbon atoms of the alkyl group may be less than the number of carbon atoms of the main chain including the carboxylic acid from the viewpoint of steric hindrance.

[0109] R 1 The alkoxy group may have 1 to 10 carbon atoms or 1 to 5 carbon atoms. The alkyl portion of the alkoxy group may be linear or branched, or may be linear. When the alkyl portion of the alkoxy group is linear, the number of carbon atoms may be less than the number of carbon atoms of the main chain including the carboxylic acid from the viewpoint of steric hindrance.

[0110] As R 1 The alkylamino group may be, for example, a monoalkylamino group or a dialkylamino group. The number of carbon atoms of the monoalkylamino group may be 1 to 10 or 1 to 5. The alkyl portion of the monoalkylamino group may be linear or branched, or may be linear. The number of carbon atoms of the dialkylamino group may be 1 to 20 or 1 to 10. The alkyl portion of the dialkylamino group may be linear or branched, or may be linear.

[0111] The flux may be a compound having two carboxyl groups (dicarboxylic acid). Compared with a compound having one carboxyl group (monocarboxylic acid), a compound having two carboxyl groups is less likely to volatilize even at high temperatures during connection, thereby further suppressing the generation of voids. Compared with the case of using a compound having three or more carboxyl groups, a compound having two carboxyl groups can further suppress the increase in viscosity of the adhesive during storage / connection operations. As a result, the connection reliability of the semiconductor device can be further improved.

[0112] The flux may contain a compound represented by the following formula (2). In formula (2), R 1 Represents an electron-donating group, R 2 represents a hydrogen atom or an electron donating group, and n represents an integer of 0 to 10. n may be an integer of 2 to 10 or an integer of 2 to 8. A flux containing the compound represented by formula (2) can contribute to improving the reflow resistance and connection reliability of a semiconductor device.

[0113]

[0114] The flux may include a compound having an electron donating group substituted at the 2-position of a dicarboxylic acid selected from succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid.

[0115] The melting point of the flux may be 150°C or less, 140°C or less, or 130°C or less. The melting point of the flux may be 25°C or more, or 50°C or more. The melting point of the flux can be measured, for example, by using a device in which a capillary tube containing a sample is installed on a double-tube thermometer and heated in a hot water tank. The melting point of the flux may be higher than the temporary crimping temperature for forming the temporary crimping body.

[0116] The content of the flux may be 0.5 to 10% by mass or 0.5 to 5% by mass based on the mass of the thermosetting adhesive layer 3 or the total mass of components other than the solvent in the thermosetting adhesive.

[0117] The thermosetting adhesive layer 3 and the thermosetting adhesive may further include a filler, which may be an inorganic filler, an organic filler or a combination thereof.

[0118] Examples of inorganic fillers include glass, silica, alumina, titanium oxide, carbon black, mica, and boron nitride. The inorganic filler may be silica, alumina, titanium oxide, and boron nitride, or one or more selected from silica, alumina, and boron nitride. The filler may be a whisker, examples of which include aluminum borate, aluminum titanate, zinc oxide, calcium silicate, magnesium sulfate, and boron nitride.

[0119] The organic filler may be a resin filler, and examples thereof include particles containing a resin selected from polyurethane, polyimide, methyl methacrylate resin, and methyl methacrylate-butadiene-styrene copolymer resin (MBS).

[0120] The content of the filler may be 30 to 90 mass %, 30 to 80 mass % or 30 to 50 mass % based on the mass of the thermosetting adhesive layer 3 or the total mass of components other than the solvent in the thermosetting adhesive.

[0121] The thermosetting adhesive layer 3 and the thermosetting adhesive may further contain other components such as an ion trapping agent, an antioxidant, a silane coupling agent, a titanium coupling agent, and a leveling agent, etc. These may be used alone or in combination of two or more.

[0122] The thermosetting adhesive used to form the thermosetting adhesive layer 3 may further contain a solvent for dissolving or dispersing each component. The film-like thermosetting adhesive can be produced by applying a thermosetting adhesive (resin varnish) containing a solvent on a base film and drying the coated film.

[0123] The solvent used to prepare the resin varnish is selected from solvents that can uniformly dissolve or disperse the components. The solvent may be an organic solvent, examples of which include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, diethylene glycol dimethyl ether, toluene, benzene, xylene, methyl ethyl ketone, tetrahydrofuran, ethyl cellosolve, ethyl cellosolve acetate, butyl cellosolve, dioxane, cyclohexanone, and ethyl acetate. These organic solvents can be used alone or in combination of two or more.

[0124] Examples of substrate films include polyolefin films such as polypropylene films and polymethylpentene films, polyester films such as polyethylene terephthalate films and polyethylene naphthalate films, polyimide films, and polyetherimide films. The substrate film may be a single-layer film formed of these films, or a multilayer film composed of two or more films.

[0125] When the thermosetting adhesive layer 3 has high fluidity near the starting temperature, it is easy to ensure good conductivity. Therefore, the thermosetting adhesive layer 3 can show a shear viscosity of 10000 Pa·s or less, 9000 Pa·s or less, 8000 Pa·s or less, 7000 Pa·s or less, 6000 Pa·s or less, 5000 Pa·s or less, 4000 Pa·s or less, 3000 Pa·s or less, or 2000 Pa·s or less at a temperature 20°C lower than the starting temperature. The thermosetting adhesive layer 3 can show a shear viscosity of 500 Pa·s or more or 1000 Pa·s or more at a temperature 20°C lower than the starting temperature.

[0126] The shear viscosity of the thermosetting adhesive layer 3 at 40° C. may be 10,000 Pa·s or more, or 200,000 Pa·s or less, or 150,000 Pa·s or less.

[0127] The minimum value of the shear viscosity (minimum melt viscosity) of the thermosetting adhesive layer 3 can be 500 Pa·s or more and 3000 Pa·s or more and 2500 Pa·s or less. When the minimum melt viscosity of the thermosetting adhesive layer 3 is within this range, there is a tendency that it is not easy to leave gaps in the adhesive layer. In addition, in the temporary pressure-bonding process, there is a tendency that the thermosetting adhesive is easily removed from the connection parts.

[0128] The shear viscosity of the thermosetting adhesive layer 3 at each temperature and the minimum value of the shear viscosity can be the value read from the viscosity curve showing the relationship between the shear viscosity (complex viscosity) and the temperature obtained when the viscoelasticity of the sample of the thermosetting adhesive layer 3 is measured under the conditions of a heating rate of 10°C / min, a frequency of 10 Hz, and a strain of 1%. The sample for the viscoelasticity measurement can be, for example, a laminate having a thickness of 300 to 450 μm obtained by laminating a plurality of thermosetting adhesive layers. The viscosity measuring device can be, for example, ARES manufactured by TA Instruments.

[0129] The shear viscosity of the thermosetting adhesive layer 3 can be adjusted within a desired range by adjusting the type and content of the polymer component or the filler, for example.

[0130] The gel time of the thermosetting adhesive layer 3 can be 10 seconds or more and 30 seconds or less at 200°C. When the gel time is within this range, it can help suppress residual voids and improve connection reliability. The gel time is the time from when the thermosetting adhesive layer 3 is placed on a hot plate at 200°C until the thermosetting adhesive layer 3 is gelled. The gel time of the thermosetting adhesive layer 3 can be adjusted by the type and content of the curing agent, etc.

[0131] Example

[0132] The present invention is not limited to the following examples.

[0133] 1.Raw materials

[0134] (a) Epoxy resin

[0135] ·Multifunctional solid epoxy resin having a trisphenol methane skeleton (EP1032H60, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 800 to 2000)

[0136] Bisphenol F type liquid epoxy resin (YL983U, manufactured by Mitsubishi Chemical Corporation, molecular weight: about 336)

[0137] Flexible semi-solid epoxy resin (YX7110B80, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 1000 to 5000)

[0138] (b) Curing agent

[0139] 2,4-Diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (2MAOK-PW, manufactured by SHIKOKU CHEMICALS CORPORATION)

[0140] (c) High molecular weight components

[0141] Phenoxy resin (FX-293, manufactured by NIPPON STEEL Chemical & Material Co., Ltd., Tg: about 160°C, weight average molecular weight: 40,000 to 50,000)

[0142] (d) Flux

[0143] Glutaric acid (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: about 98°C)

[0144] (e) Filling

[0145] Inorganic fillers

[0146] Silica filler (SE2030, manufactured by Admatechs Co., Ltd., average particle size: 500 nm)

[0147] · Epoxysilane surface treated silica filler (SE2030, manufactured by Admatechs Co., Ltd., average particle size: about 500 nm)

[0148] Methacrylic acid surface treated nano-silica filler (YA050C, manufactured by Admatechs Co., Ltd., average particle size: about 50 nm)

[0149] Organic fillers

[0150] Resin filler (EXL-2655, manufactured by Dow Chemical Japan Ltd., core-shell type organic fine particles)

[0151] 2. Preparation of film-like thermosetting adhesive

[0152] A resin varnish containing each raw material at the ratio (parts by mass) shown in Table 1 was applied on a base film, and the coated film was dried to prepare two types of film-like thermosetting adhesives A and B (thickness 40 μm).

[0153] DSC (Differential Scanning Calorimetry)

[0154] Regarding the thermosetting adhesive A or B, DSC was measured under the following conditions.

[0155] Sample size: 10 mg

[0156] Heating rate: 10℃ / min

[0157] Air or nitrogen atmosphere

[0158] The starting temperature, peak temperature and calorific value were obtained for the exothermic peak showing the maximum heat generation in the obtained DSC curve. Thermosetting adhesives A and B show an integrated exothermic peak including two maximum points. The temperature of the intersection of the tangent line of the curve at the position where the slope of the exothermic peak curve becomes the largest and the extended line of the baseline of the DSC curve, which is closer to the low temperature side than the maximum point on the low temperature side of the two maximum points of the exothermic peak, is set as the starting temperature. The peak temperature is the temperature of the point with the highest height among the two maximum points.

[0159] Reaction rate

[0160] Thermosetting adhesives A and B were heated at 150°C or 170°C for 30 seconds. DSC was measured for the heated thermosetting adhesive under the same conditions as above to obtain the calorific value Q1 of the exothermic peak. The reaction rate was obtained from Q1 and the calorific value Q0 of the thermosetting adhesive before heating using the following formula.

[0161] Reaction rate (%) = {(Q0-Q1) / Q0} × 100

[0162] Shear viscosity

[0163] Thermosetting adhesives were laminated using a laminating machine to form a laminate with a thickness of more than 500 μm. A test sample with a size of 10.0 mm × 10.0 mm was cut out from the laminate. A viscoelasticity measuring device (product name: ARES-G2, manufactured by TA Instruments) was used to measure the shear viscosity (viscosity rate) of the test sample under the following conditions. The minimum values ​​of shear viscosity and melt viscosity (minimum melt viscosity) at 40°C, 80°C, 130°C, 150°C or 160°C were obtained from the viscosity curve showing the relationship between shear viscosity and temperature. The temperature indicating the minimum melt viscosity is also shown in Table 1.

[0164] Mode: Cut

[0165] Heating rate: 10℃ / min

[0166] Frequency: 10Hz

[0167] Strain: 1%

[0168] [Table 1]

[0169]

[0170] 3. Manufacturing of semiconductor devices

[0171] Temporary crimping process

[0172] The following first semiconductor chip and second semiconductor chip were prepared.

[0173] 1st semiconductor chip:

[0174] Semiconductor chip (size: 7.3 mm square, thickness: 50 μm, total height of Cu column and Sn-Ag solder: about 45 μm, number of bumps: 1048 pins, bump pitch along the outer periphery: 80 μm, bump pitch inside: 300 μm, product name: WALTS-TEG CC80, manufactured by Waltz Corporation) in which connection portions formed by Cu columns and solder bumps (melting point: about 217°C) containing Sn-Ag alloy disposed thereon are disposed at different pitches along the outer periphery of the chip body and inside thereof

[0175] Second semiconductor chip

[0176] A second semiconductor chip (chip size: 10 mm square, thickness: 100 μm, product name: WALTS-TEG IP80, manufactured by Waltz Co., Ltd.) having connection portions further plated with Au (melting point: about 1065° C.) on nickel plating and arranged at different pitches along the outer periphery of the chip body and inside thereof

[0177] A film-like thermosetting adhesive A or B cut into a size of 7.3 mm square is attached to the connection surface of the first semiconductor chip provided with a connection portion. The first semiconductor chip attached with the thermosetting adhesive is picked up by the pressing head of a flip chip bonder (FCB3, manufactured by Panasonic Corporation). The picked up first semiconductor chip is placed on the second semiconductor chip placed on the workbench in an orientation with the thermosetting adhesive sandwiched between the first semiconductor chip and the second semiconductor chip, and then the formed stack is heated and pressurized by the pressing head of the flip chip bonder, thereby obtaining a temporary pressed body. The temporary pressed body was produced under several conditions of temperature, time and pressure shown in Table 2. The temperature is the set temperature of the pressing head, and the pressure is the load applied to the entire first semiconductor chip by the pressing head.

[0178] (Formal crimping process)

[0179] By heating each temporary press-bonded body in a pressurized atmosphere with a pressure of 0.8 MPa in a heating furnace (pressurized reflow furnace, VPF300HP, manufactured by SHINAPEX CO., LTD.), an evaluation connection body (semiconductor device) having a first semiconductor chip and a second semiconductor chip was formed. The temperature of the pressurized atmosphere was changed under the following temperature conditions C1 or C2.

[0180] C1: The temperature is raised at 3°C / s and maintained at 260°C (main bonding temperature) for 10 minutes (the time at a temperature above the melting point of the Sn-Ag alloy solder: about 630 seconds)

[0181] C2: Heating at 3°C / sec, holding at 175°C (preheating temperature) for 10 minutes, heating at 3°C / sec and holding at 230°C (main crimping temperature) for 0.1 seconds (time at a temperature above the melting point of the solder containing the Sn-Ag alloy: about 30 seconds)

[0182] 4. Evaluation

[0183] (1) Connectivity

[0184] Conductivity

[0185] The conduction state between the connection parts of the temporary crimped body and the connected body was measured using a digital multimeter (CDM-09N, manufactured by CUSTOM CO., LTD.).

[0186] OK: Conductivity is confirmed in the connection portion on the inner circumference side.

[0187] NG: No conduction was confirmed in the connection portion on the inner circumference side.

[0188] Solder status

[0189] The cross section of the connection portion was observed by SEM (scanning electron microscope SU1510, manufactured by Hitachi High-Tech Corporation). The state of the solder in the cross section of the connection portion was evaluated according to the following criteria.

[0190] A: No defects or gaps

[0191] B: Defects or gaps

[0192] C: Solder collapse

[0193] D: Poor connection (connection parts are not in contact with each other)

[0194] Figure 5 This is a picture of the connection portion in the connection body of Example 4 in which the solder state is A. Figure 6This is a picture of the connection portion in the connection body of Example 2 in which the solder state is B. Figure 7 This is a photograph of the connection portion in the connection body of Comparative Example 2 in which the solder state is C. Figure 8 These are photographs of the connection portion in the connection body of Comparative Example 1 in which the solder states are C and D.

[0195] (2) Gap

[0196] The remaining state of voids in the connected bodies after full crimping was evaluated using SAM (ultrasonic digital imaging diagnostic apparatus IS-350, manufactured by Insight Corporation). It was confirmed that voids were appropriately removed in all connected bodies.

[0197] [Table 2]

[0198]

[0199] As shown in Table 2, it was confirmed that by combining a temporary crimping process accompanied by heating to a temporary crimping temperature above the starting temperature and a formal crimping process accompanied by pressurization in a pressurized atmosphere based on a low pressure of less than 1.50 MPa, good conductivity can be ensured and deformation of the connection portion (collapse of the solder) can be suppressed.

[0200] Explanation of symbols

[0201] 1- first circuit component, 2- second circuit component, 3- thermosetting adhesive layer, 11- metal column, 12- bump,

[0202] 15- first connection part, 25- second connection part, 41, 42- pressing members, 50- heating furnace, 100- laminated body,

[0203] 101-temporary crimping body, 102-connecting body (semiconductor device).

Claims

1. A method for manufacturing a semiconductor device, comprising: A process of heating and pressurizing a laminate having a first circuit component having a first connecting portion comprising a first metal material, a second circuit component having a second connecting portion comprising a second metal material, and a thermosetting adhesive layer with the thermosetting adhesive layer interposed between the first circuit component and the second circuit component by a pair of opposing pressing components, thereby forming a temporary crimped body in which the first connecting portion is in contact with the second connecting portion; and The method further comprises the step of heating the temporary crimping body to a predetermined final crimping temperature under a pressurized atmosphere to form a connecting body in which the first connecting portion and the second connecting portion are electrically connected through metal bonding between the first metal material and the second metal material. The first circuit component is a semiconductor chip or a semiconductor wafer, and the second circuit component is a wiring circuit substrate, a semiconductor chip or a semiconductor wafer. The stack is pressurized by the pair of pressing members at a predetermined pressure of 1.50 MPa or less, During a part or the whole of the period during which the stacked body is heated and pressurized by the pair of pressing members, at least one of the pair of pressing members is heated to a predetermined temporary pressing temperature, wherein the temporary pressing temperature is a temperature that is not less than the starting temperature of the thermosetting adhesive layer and is lower than the formal pressing temperature, The onset temperature is the onset temperature of a heat generation peak showing a maximum heat generation amount in a DSC curve obtained by differential scanning calorimetry under the condition that the sample of the thermosetting adhesive layer is heated at a heating rate of 10° C. / min. The main compression bonding temperature is a temperature higher than or equal to at least one of a melting point of the first metal material or a melting point of the second metal material.

2. The method according to claim 1, wherein: The predetermined pressure is not less than 0.94 MPa and not more than 1.50 MPa.

3. The method according to claim 1, wherein: The temporary compression bonding temperature is equal to or higher than the starting temperature and equal to or lower than 200° C.

4. The method according to claim 1, wherein: The time for which the stacked body is heated and pressurized by the pair of pressing members is 5 seconds or less.

5. The method according to claim 1, wherein: The thermosetting adhesive layer exhibits a shear viscosity of 10000 Pa·s or less at a temperature 20° C. lower than the starting temperature, the shear viscosity being a value measured under conditions of a heating rate of 10° C. / min, a frequency of 10 Hz, and a strain of 1%.

6. The method according to claim 1, wherein: The time for heating the temporarily pressed body to a temperature equal to or higher than at least one of a melting point of the first metal material or a melting point of the second metal material in the pressurized atmosphere is 60 seconds or less.

7. The method according to claim 1, wherein: The pressure of the pressurized atmosphere exceeds the atmospheric pressure and is 0.90 MPa or less.

8. The method according to claim 1, wherein: The thermosetting adhesive layer comprises: Thermosetting resins having a molecular weight of less than 10,000; a curing agent for the thermosetting resin; and A high molecular weight component having a weight average molecular weight of 10,000 or more.

9. The method according to claim 8, wherein: The glass transition temperature of the polymer component is 200° C. or lower.

10. The method according to claim 1, wherein: The thermosetting adhesive layer has a shear viscosity of 10,000 Pa·s or more at 40° C.

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