Method for manufacturing semiconductor device

Abstract

A method for manufacturing a semiconductor device is provided, comprising: forming a temporarily bonded body by heating and pressurizing a laminate having a first circuit member, a second circuit member, and a thermosetting adhesive layer by means of pressing members; and forming a connection body by heating the temporarily bonded body in a pressurized atmosphere. The first circuit member may be a semiconductor chip. The laminate is pressed by the pressing members at a predetermined pressure of 1.50 MPa or less. In some or all of the time during which the laminate is heated and pressed by the pressing members, at least one of the pressing members is heated to a temporary bonding temperature equal to or higher than an onset temperature of the thermosetting adhesive layer.

Description

Method for manufacturing semiconductor device

[0001] The present disclosure relates to a method for manufacturing a semiconductor device.

[0002] In the manufacture of semiconductor devices, a flip-chip connection method is sometimes adopted in which conductive protrusions called bumps are provided on a semiconductor chip or a wiring circuit board as connecting portions, and the semiconductor chip is connected to the wiring circuit board or another semiconductor chip via an adhesive by connecting the connecting portions together. For example, Patent Document 1 discloses the manufacture of a semiconductor device using a flip-chip connection method that includes a step of obtaining a temporary compression-bonded body in which semiconductor chips are temporarily compressed together, and a step of joining the connecting portions together by heating the temporary compression-bonded body while applying pressure.

[0003] International Publication No. 2018 / 194156

[0004] When manufacturing a semiconductor device using a method that involves connecting a connection portion of a semiconductor chip or semiconductor wafer to a connection portion of another semiconductor chip, etc. by metal bonding, a portion of the connection portion may be crushed and significantly deformed during the connection. Such significant deformation of the connection portion may result in a decrease in connection reliability.

[0005] The present disclosure relates to suppressing deformation of a connection portion due to connection while ensuring good electrical continuity when manufacturing a semiconductor device by a method that includes 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.

[0006] The present disclosure includes the following: [1] A method for manufacturing a semiconductor device, comprising: heating and pressurizing a laminate having a first circuit member having a first connecting portion containing a first metal material, a second circuit member having a second connecting portion containing a second metal material, and a thermosetting adhesive layer, with a pair of opposing pressing members, thereby forming a pre-compression-bonded body in which the first connecting portion and the second connecting portion are in contact with each other; and heating the pre-compression-bonded body to a predetermined full-compression temperature in a pressurized atmosphere, thereby forming a connection body in which the first connecting portion and the second connecting portion are electrically connected by metallic bonding between the first metal material and the second metal material, wherein the first circuit member is a semiconductor chip or a semiconductor wafer, and the second circuit member is a wired circuit board, a semiconductor chip, or a semiconductor wafer; and the laminate is pressed by the pair of pressing members at a predetermined pressure of 1.50 MPa or less. [2] The method according to [1], wherein the predetermined pressure is 0.94 MPa or more and 1.50 MPa or less. [3] The method according to [1] or [2], wherein the pre-compression bonding temperature is equal to or greater than the onset temperature and lower than the main compression bonding temperature. [4] The method according to any one of [1] to [3], wherein the laminate is heated and pressed by the pair of pressing members for 5 seconds or less.[5] The method according to any one of [1] to [4], wherein the thermosetting adhesive layer exhibits a shear viscosity of 10,000 Pa s or less at a temperature 20°C lower than the onset temperature, the shear viscosity being 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 any one of [1] to [5], wherein the pre-bonded body is heated to at least one of the melting points of the first metal material and the second metal material under the pressurized atmosphere for 60 seconds or less. [7] The method according to any one of [1] to [6], wherein the pressure of the pressurized atmosphere is higher than atmospheric pressure and 0.90 MPa or less. [8] The method according to any one of [1] to [7], wherein the thermosetting adhesive layer comprises: 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. [9] The method according to [8], wherein the polymer component has a glass transition temperature of 200°C or less.

[10] The method according to any one of [1] to [9], wherein the thermosetting resin layer exhibits a shear viscosity of 10,000 Pa·s or more at 40°C.

[0007] When manufacturing a semiconductor device using a method that includes 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 due to the connection can be suppressed.Furthermore, good electrical continuity between the connection portions can be easily ensured.

[0008] 1 is a process chart showing an example of a method for manufacturing a semiconductor device; FIG. 2 is a process chart showing an example of a method for manufacturing a semiconductor device; FIG. 3 is a process chart showing an example of a method for manufacturing a semiconductor device; FIG. 4 is a schematic diagram showing a method for determining an onset temperature from a DSC curve; FIG. 5 is a cross-sectional photograph of a connection portion in a connector; FIG. 6 is a cross-sectional photograph of a connection portion in a connector; FIG. 7 is a cross-sectional photograph of a connection portion in a connector.

[0009] The present invention is not limited to the following examples.

[0010] 1, 2, and 3 are process diagrams illustrating an example of a method for manufacturing a semiconductor device. The method illustrated in FIGS. 1 to 3 includes preparing a laminate 100 having a first circuit member 1 having a first connecting portion 15 containing a first metal material, a second circuit member 2 having a second connecting portion 25 containing a second metal material, and a thermosetting adhesive layer 3; heating and pressurizing the laminate 100 with a pair of opposing pressing members 41, 42 to form a pre-bonded body 101 in which the first connecting portion 15 and the second connecting portion 25 are in contact; and heating the pre-bonded body 101 to a full-bonding temperature under a pressurized atmosphere to form a connecting body 102 (semiconductor device) in which the first connecting portion 15 and the second connecting portion 25 are electrically connected by metallic bonding between the first metal material and the second metal material. The first circuit member 1 may be a semiconductor chip or a semiconductor wafer. The second circuit member 2 may be a printed circuit board, a semiconductor chip, or a semiconductor wafer.

[0011] The laminate 100 is prepared, for example, as shown in FIG. 1 , by a method including: preparing a first circuit member 1 (e.g., a semiconductor chip) having a plate-shaped main body 10 and a plurality of first connection portions 15 arranged on the main surface of the main body 10; providing a thermosetting adhesive layer 3 on the surface of the first circuit member 1 facing the first connection portions 15; preparing a second circuit member 2 having a plate-shaped main body 20 and second connection portions 25 arranged on the main surface of the main body 20; and placing the first circuit member 1 on the second circuit member 2 so that the thermosetting adhesive layer 3 is interposed between the first circuit member 1 and the second circuit member 2 and the first connection portions 15 and the second connection portions 25 are arranged opposite each other.

[0012] The main body 10 of the first circuit member 1 (semiconductor chip or semiconductor wafer) is not particularly limited and may include various semiconductor substrates and integrated circuits, such as elemental semiconductors composed of the same elements, such as silicon and germanium, or compound semiconductors, such as gallium arsenide and indium phosphide.

[0013] The first connection portion 15 of the first circuit member 1 has a metal pillar 11 and a bump 12 provided on the metal pillar 11. The first metal material is contained in the bump 12, which is the portion bonded to the second connection portion 25. The metal pillar 11 may be, for example, a copper pillar. The melting point of the first metal material contained in the bump 12 may be 220°C or higher and 330°C or lower, or 140°C or higher and 220°C or lower. The bump 12 may be a solder bump containing solder as the first metal material. The first metal material may be solder containing a Sn—Ag alloy, a Sn—Pb alloy, a Sn—Bi alloy, a Sn—Cu alloy, or a Sn—Ag—Cu alloy.

[0014] The wired circuit board serving as the second circuit member 2 has, for example, an insulating substrate serving as the main body 20 and wiring including the 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. The semiconductor chip serving as the second circuit member 2 may have a semiconductor substrate and an integrated circuit, similar to the first circuit member 1. The semiconductor wafer serving as the second circuit member 2 may include multiple portions corresponding to the semiconductor chips.

[0015] The second connection portion 25 of the second circuit member 2 can be, for example, a metal pad including 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 a Sn—Ag alloy, a Sn—Pb alloy, a Sn—Bi alloy, a Sn—Cu alloy, or a Sn—Ag—Cu alloy.

[0016] The thermosetting adhesive layer 3 is a layer formed from a thermosetting adhesive and is provided on the first circuit member 1, for example, by attaching a pre-formed film-like thermosetting adhesive to the first circuit member 1. The film-like thermosetting adhesive can be attached to the first circuit member 1 by, for example, heat pressing, roll lamination, or vacuum lamination. The area and thickness of the film-like thermosetting adhesive are appropriately set depending on the size of the first circuit member 1, the height of the first connection portion 15, etc. The thickness of the film-like thermosetting adhesive and the thermosetting adhesive layer 3 may be, for example, 1 μm or more and 60 μm or less. A semiconductor wafer to which the film-like thermosetting adhesive has been attached may be diced into individual pieces to prepare semiconductor chips to which the thermosetting adhesive layer 3 has been attached as the first circuit member 1. Details of the thermosetting adhesive layer 3 and the thermosetting adhesive that forms it will be described later.

[0017] 2, a pair of pressing members 41, 42 are arranged opposite each other, and the laminate 100 is sandwiched between the pressing member 41 arranged on the second circuit member 2 side and the pressing member 42 arranged on the first circuit member 1 side, thereby applying heat and pressure. A pre-pressure-bonding process including this heating and pressure forms a pre-pressure-bonded body 101. During part or all of the time during which the laminate 100 is heated and pressed by the pressing members 41, 42, the pressing member 41, the pressing member 42, or both, are heated to a predetermined pre-pressure-bonding temperature.

[0018] The laminate 100 is heated by heat transfer from the pressing member in contact with the laminate 100. For example, the pressing member 41 arranged on the second circuit member 2 side may be a stage, and the pressing member 42 on the first circuit member 1 side may be a crimping head. The first circuit member 1 may be adsorbed onto the pressing member 42, which is a crimping head, and the connection portions may be aligned by moving the crimping head. For this purpose, a crimping machine such as a flip-chip bonder having a crimping head may be used. The first circuit member 1 and the thermosetting adhesive layer 3, which are adsorbed onto the pressing member 42, which is a crimping head, may be placed on the second circuit member 2 to form the laminate 100, and the laminate 100 may then be pressed by the crimping head (pressing member 42).

[0019] The temporary pressure bonding temperature is a constant temperature set in a range equal to or higher than the onset temperature of the thermosetting adhesive layer 3. The onset temperature here refers to the onset temperature of the exothermic peak exhibiting the largest heat release in a DSC curve obtained by differential scanning calorimetry under conditions in which a sample that is part of the thermosetting adhesive layer 3 is heated at a temperature increase rate of 10°C / min. FIG. 4 is a schematic diagram showing a method for determining the onset temperature from a DSC curve. The DSC curve shown in FIG. 4 includes a baseline L0 in the temperature range of 60 to 280°C and an exothermic peak P due to the curing reaction of the thermosetting adhesive layer 3, which is observed midway along the baseline L0. The onset temperature is the temperature T at the intersection of an extension line L1 of the baseline L0 below the exothermic peak P and a tangent line L2 to the DSC curve at the point where the DSC curve exhibits the maximum gradient on the lower side of the temperature at which the exothermic peak P exhibits its maximum maximum value. In addition to the maximum peak exhibiting the maximum maximum value, the exothermic peak may include one or more shoulder peaks. When the exothermic peak includes one or more shoulder peaks located on the lower side than the temperature at which the maximum maximum value is shown, the onset temperature is the temperature at the intersection of the tangent to the DSC curve at the point where the DSC curve on the lower temperature side of the lowest shoulder peak shows the maximum slope and an extension of the baseline of the DSC curve.

[0020] If the pre-bonding temperature is equal to or higher than the onset temperature, the viscosity of the thermosetting adhesive layer 3 is significantly reduced during the heating and pressurizing process to form the pre-bonded body, and the thermosetting adhesive layer 3 is likely to be sufficiently removed from between the first connecting portion 15 and the second connecting portion 25. Therefore, even if the heating and pressurizing conditions in the main bonding process to form the connecting body 102 from the pre-bonded body 101 are relatively mild, good conductivity is likely to be ensured. As a result, deformation of the connecting portion (e.g., bump 12) in the connecting body 102 can be suppressed.

[0021] From the above viewpoint, the temporary compression bonding temperature may be a temperature higher than the onset temperature by 1° C., 2° C., 3° ​​C., 4° C., or 5° C. or more. The temporary compression bonding temperature may be 200° C. or lower, 195° C. or lower, 190° C. or lower, or 185° C. or lower. The temporary compression bonding temperature is usually a temperature lower than the melting points of the first metal material and the second metal material.

[0022] The onset temperature of the thermosetting adhesive layer 3 may be, for example, 140° C. or higher and 190° C. or lower. The onset temperature of the thermosetting adhesive layer 3 may be 145° C. or higher, 150° C. or higher, or 155° C. or higher, or 185° C. or lower, 180° C. or lower, 175° C. or lower, 170° C. or lower, or 165° C. or lower.

[0023] While the laminate 100 is heated and pressurized by the pressing members 41 and 42, the temperature (heating temperature) of the pressing members 41 and 42, or both of them, may be substantially maintained at a constant pre-compression bonding temperature equal to or higher than the onset temperature, or may fluctuate. However, even when the heating temperature is substantially maintained at a constant pre-compression bonding temperature, the actual heating temperature may fluctuate to some extent (for example, within a range of the pre-compression bonding temperature ±1°C). When the heating temperature fluctuates, it is set so that the maximum temperature becomes the predetermined pre-compression bonding temperature.

[0024] If the time (pre-pressure bonding time) during which the laminate 100 is heated and pressurized by the pressing members 41, 42 is appropriately short, the curing reaction of the thermosetting adhesive layer 3 tends to be less likely to proceed excessively at the stage before heating at the main pressure bonding temperature. Therefore, the pre-pressure bonding 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.

[0025] To form the temporary pressure-bonded body 101, a predetermined pressure is applied to the laminate 100 by the pressing members 41, 42. If this pressure is appropriately small, deformation of the connection portions is easily suppressed while voids and the thermosetting adhesive layer 3 are sufficiently removed from between the connection portions. From this perspective, the predetermined pressure for forming the temporary pressure-bonded body 101 may be 1.50 MPa or less, or may be 0.94 MPa or more and 1.50 MPa or less. Applying pressure within this range may also be advantageous in terms of avoiding a decrease in connection reliability due to damage to the connection portions. From a similar perspective, the predetermined pressure for forming the temporary pressure-bonded body 101 may be 1.45 MPa or less, 1.40 MPa or less, or 1.35 MPa or less, or may be 1.0 MPa or more, 1.05 MPa or more, or 1.1 MPa or more. To form the temporary pressure-bonded body 101, the load applied to the entire laminate 100 by the pressing members 41, 42 may be 50 N or more and 80 N or less.

[0026] An additional thermosetting adhesive layer and an additional circuit member (e.g., a semiconductor chip) may be further provided on the side of the first circuit member 1 opposite to the second circuit member 2. In this case, each circuit member may be laminated sequentially by a pre-compression bonding process, or a pre-compression bonded body may be formed by a pre-compression bonding process in which a laminate having three or more circuit members is heated and pressurized all at once. When three or more circuit members are laminated, a semiconductor chip having a TSV structure may be used as the circuit member.

[0027] 3A, the pre-bonded body 101 is heated to a predetermined final bonding temperature in a pressurized atmosphere in a heating furnace 50, thereby forming a connecting body 102. The final bonding temperature for forming the connecting body 102 is set to a temperature equal to or higher than at least one of the melting points of the first metal material and the second metal material. By heating the pre-bonded body 101 at a heating temperature that reaches a final bonding temperature equal to or higher than at least one of the melting points of the first metal material and the second metal material, a metal bond is formed between the first metal material and the second metal material. For example, in the final bonding process, the bump 12 of the first connecting portion 15 melts, and the deformed bump 12 is interposed between the metal pillar 11 and the second connecting portion 25, thereby electrically connecting the first connecting portion 15 and the second connecting portion 25.

[0028] The heating in the main pressure-bonding step also progresses the curing reaction of the thermosetting adhesive layer 3, and an adhesive layer 3A, which is a cured thermosetting adhesive, is formed. For example, the connecting body 102 can be a semiconductor device including a semiconductor chip as the first circuit member 1, a second circuit member 2, and an adhesive layer 3A. After the main pressure-bonding step, the connecting body 102 may be further heated to further progress the curing reaction of the thermosetting adhesive.

[0029] The furnace 50 may be, for example, a pressurized reflow furnace or a pressurized oven. The gas forming the pressurized atmosphere within the furnace 50 may include air, nitrogen, or formic acid.

[0030] The heating temperature of the pre-bonded body 101 in the final bonding step may be constant or may vary, but the pre-bonded body 101 is heated so that the maximum temperature reaches the final bonding temperature. The heating temperature here may be the temperature of the pressurized atmosphere.

[0031] The temperature for the full-compression bonding may be, for example, 220° C. or higher and 330° C. or lower. When the temperature for the full-compression bonding is within this range, a good metal bond is likely to be formed while suppressing scattering of the connection portion and the formation of voids in the connection portion due to excessive alloy growth accompanying the metal bond. This tendency is particularly noticeable when the first metal material or the second metal material is solder, for example.

[0032] In the main bonding process, the time during which the temporary compression body 101 is heated to at least one of the melting points of the first metal material and the second metal material may be 60 seconds or less. Alternatively, the time during which the temporary compression body 101 is heated to at least 220°C may be 60 seconds or less. According to this condition of the main bonding process, a good metal bond is likely to be formed while suppressing scattering of the connection portion and the formation of voids in the connection portion due to excessive alloy growth associated with the metal bond. In the main bonding process, the time during which the temporary compression body 101 is heated to at least one of the melting points of the first metal material and the second metal material may be 5 seconds or more. In the main bonding process, the time during which the temporary compression body 101 is heated to at least 220°C may be 5 seconds or more.

[0033] Before being heated to the final bonding temperature, the pre-bonded body 101 may be heated in a pressurized atmosphere at a constant preheating temperature that is lower than the melting points of the first metal material and the second metal material. Heating at this preheating temperature may contribute to suppressing voids in the connection. The time for which the pre-bonded body 101 is heated at the constant preheating temperature may be 1 minute or more, or 2 minutes or more, or 20 minutes or less, or 15 minutes or less. The preheating temperature may be higher than the pre-bonding temperature, and may be 160°C or more, 165°C or more, or 170°C or more. The preheating temperature may be 200°C or less, 195°C or less, 190°C or less, 185°C or less, or 180°C or less.

[0034] The pressure of the pressurized atmosphere in the heating furnace 50 is set appropriately depending on the size and number of circuit components, etc. The pressure of the pressurized atmosphere may be, for example, above atmospheric pressure and not more than 1 MPa. A higher pressure may contribute to, for example, suppressing voids and improving connectivity. A lower pressure may contribute to suppressing fillets. From these perspectives, the pressure of the pressurized atmosphere may be, for example, above atmospheric pressure and not more than 0.90 MPa, or 0.20 MPa to 0.80 MPa.

[0035] A plurality of pre-bonded bodies may be heated collectively in one heating furnace 50. The pressurized atmosphere allows the pre-bonded bodies to be pressurized with high uniformity. Heating the pre-bonded bodies in a pressurized atmosphere also tends to suppress the formation of fillets, which are adhesive layers that protrude from the outer periphery of the connection body, compared to when the pre-bonded bodies are heated and pressurized using a pressing member.

[0036] The thermosetting adhesive layer 3 and the thermosetting adhesive that forms it will be described in detail below.

[0037] The thermosetting adhesive layer 3 may be a layer formed from 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.

[0038] Thermosetting resins are compounds that form crosslinked polymers through a curing reaction, examples of which include epoxy resins. The epoxy resin can be a compound having two or more epoxy groups. Examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, naphthalene epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, phenol aralkyl epoxy resins, biphenyl epoxy resins, triphenylmethane epoxy resins, and dicyclopentadiene epoxy resins. These can be used alone or in combination of two or more. The weight-average molecular weight of the epoxy resin is usually less than 10,000. In this specification, the weight-average molecular weight refers to the value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0039] The content of the epoxy resin may be 5% by mass or more and 75% by mass or less, 10% by mass or more and 50% by mass or less, or 15% by mass or more and 35% by mass or less, based on the mass of the thermosetting adhesive layer 3 or the total mass of the components of the thermosetting adhesive other than the solvent.

[0040] The curing agent is a component that promotes the curing reaction of the thermosetting resin. Examples of the curing agent when the thermosetting resin is an epoxy resin include a phenolic resin-based curing agent, an acid anhydride-based curing agent, an amine-based curing agent, an imidazole-based curing agent, and a phosphine-based curing agent. The curing agent may include one or more selected from the group consisting of a phenolic resin-based curing agent, an acid anhydride-based curing agent, an amine-based curing agent, and an imidazole-based curing agent, or may include an imidazole-based curing agent.

[0041] 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 may be used alone or in combination of two or more.

[0042] The equivalent ratio of the phenolic resin-based curing agent to the epoxy resin (phenolic hydroxyl group / epoxy group, molar ratio) may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0, from the viewpoints of good curability, adhesiveness, and storage stability.

[0043] Examples of the acid anhydride curing agent include methylcyclohexanetetracarboxylic dianhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, and ethylene glycol bisanhydrotrimellitate, which may be used alone or in combination of two or more.

[0044] The equivalent ratio of the acid anhydride curing agent to the epoxy resin (acid anhydride group / epoxy group, molar ratio) may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0 from the viewpoint of good curability, adhesion, and storage stability.

[0045] Amine-based curing agents are compounds having an amino group, examples of which include dicyandiamide.

[0046] The equivalent ratio of the amine curing agent to the epoxy resin (amine / epoxy group, molar ratio) may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0 from the viewpoint of good curability, adhesion, and storage stability.

[0047] The imidazole-based 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'-undecylimidazolyl-(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 isocyanuric 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 curing property, storage stability and connection reliability, 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'-ethyl The imidazole curing agent may be selected from 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. These may be used alone or in combination of two or more. Microcapsules containing these may also be used as latent curing agents.

[0048] 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.

[0049] Examples of phosphine-based curing agents include triphenylphosphine, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra(4-methylphenyl)borate, and tetraphenylphosphonium(4-fluorophenyl)borate.

[0050] 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.

[0051] The polymer component can contribute to the heat resistance and film-forming properties of the thermosetting adhesive layer. Examples of the polymer component include phenoxy resin, polyimide resin, polyamide resin, polycarbodiimide resin, cyanate ester resin, acrylic resin, polyester resin, polyethylene resin, polyethersulfone resin, polyetherimide resin, polyvinyl acetal resin, urethane resin, and acrylic rubber. The polymer component may be a copolymer containing a partial structure corresponding to a resin or rubber selected from these. From the viewpoint of heat resistance and film-forming properties, the polymer component may contain one or more selected from phenoxy resin, polyimide resin, acrylic rubber, cyanate ester resin, and polycarbodiimide resin. The polymer component may contain one or more selected from phenoxy resin, polyimide resin, and acrylic rubber. 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).

[0052] The glass transition temperature (Tg) of the polymer component may be 200°C or less, 50°C or more to 200°C or less, 50°C or more to 180°C or less, or 50°C or more to 150°C or less, from the viewpoint of the adhesiveness of the film-like thermosetting adhesive to circuit components. When the Tg of the polymer component is 50°C or more, the tack (viscous) force of the thermosetting adhesive tends to be appropriately weak. When the Tg of the polymer component is 200°C or less, the thermosetting adhesive tends to properly fill unevenness due to connection portions of circuit components, etc., and as a result, the effect of void suppression tends to be relatively greater. Here, Tg refers to the value measured using a DSC (DSC-Pyrs1, manufactured by PerkinElmer Co., Ltd.) under conditions of a sample weight of 10 mg, a heating rate of 10°C / min, and an air atmosphere.

[0053] 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 may be 200,000 or less.

[0054] The ratio Ca / Cd (mass ratio) of the epoxy resin content Ca to the polymer component content Cd may be 0.01 to 5, 0.05 to 3, or 0.1 to 2. When the ratio Ca / Cd is 0.01 or more, better curability and adhesive strength are likely to be obtained. When the ratio Ca / Cd is 5 or less, better film formability is likely to be obtained.

[0055] The thermosetting adhesive layer 3 and the thermosetting adhesive may contain a fluxing agent. The fluxing agent may be, for example, a compound having a group represented by formula (1). The fluxing agent may be a single type of compound represented by formula (1) or a combination of two or more types. In formula (1), R １ represents an electron-donating group. Examples of the electron-donating group include an alkyl group, a hydroxyl group, an amino group, an alkoxy group, and an alkylamino group. The electron-donating group may be an alkyl group, a hydroxyl group, or an alkoxyl group, or may be an alkyl group.

[0056] R １may be an alkyl group having 1 to 10 carbon atoms or 1 to 5 carbon atoms. The alkyl group may be linear or branched, or may be linear. When the alkyl group is linear, the number of carbon atoms in the alkyl group may be equal to or less than the number of carbon atoms in the main chain containing the carboxylic acid, from the viewpoint of steric hindrance.

[0057] R １ may be an alkoxy group having 1 to 10 carbon atoms or 1 to 5 carbon atoms. The alkyl group portion of the alkoxy group may be linear or branched, or may be linear. When the alkyl group portion of the alkoxy group is linear, the number of carbon atoms may be equal to or less than the number of carbon atoms in the main chain containing the carboxylic acid, from the viewpoint of steric hindrance.

[0058] R １ The alkylamino group as may be, for example, a monoalkylamino group or a dialkylamino group. The number of carbon atoms in the monoalkylamino group may be 1 to 10, or 1 to 5. The alkyl group portion of the monoalkylamino group may be linear or branched, or may be linear. The number of carbon atoms in the dialkylamino group may be 1 to 20, or 1 to 10. The alkyl group portion of the dialkylamino group may be linear or branched, or may be linear.

[0059] The fluxing agent may be a compound having two carboxyl groups (dicarboxylic acid). A compound having two carboxyl groups is less likely to volatilize at high temperatures during connection than a compound having one carboxyl group (monocarboxylic acid), and can further suppress the occurrence of voids. A compound having two carboxyl groups can further suppress the increase in viscosity of the adhesive during storage, connection work, etc., compared to a compound having three or more carboxyl groups. As a result, the connection reliability of the semiconductor device can be further improved.

[0060] The fluxing agent may contain a compound represented by the following formula (2): １ represents an electron-donating group, R ２represents 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 fluxing agent containing the compound represented by formula (2) can contribute to improving the reflow resistance and connection reliability of a semiconductor device.

[0061] The fluxing agent may include a compound in which an electron-donating group is 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.

[0062] The melting point of the fluxing agent may be 150°C or lower, 140°C or lower, or 130°C or lower. The melting point of the fluxing agent may be 25°C or higher, or 50°C or higher. The melting point of the fluxing agent can be measured, for example, by using an apparatus in which a capillary tube filled with a sample is attached to a double-tube thermometer and heated in a hot bath. The melting point of the fluxing agent may be higher than the temporary compression bonding temperature for forming the temporary compression bonded body.

[0063] The content of the fluxing agent may be 0.5 to 10 mass %, or 0.5 to 5 mass %, based on the mass of the thermosetting adhesive layer 3 or the total mass of the components of the thermosetting adhesive other than the solvent.

[0064] 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.

[0065] Examples of inorganic fillers include glass, silica, alumina, titanium oxide, carbon black, mica, and boron nitride. The inorganic filler may be one or more selected from silica, alumina, titanium oxide, and boron nitride, or silica, alumina, and boron nitride. The filler may be whiskers, examples of which include aluminum borate, aluminum titanate, zinc oxide, calcium silicate, magnesium sulfate, and boron nitride.

[0066] The organic filler may be a resin filler, examples of which include particles containing a resin selected from polyurethane, polyimide, methyl methacrylate resin, and methyl methacrylate-butadiene-styrene copolymer resin (MBS).

[0067] 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 the components of the thermosetting adhesive other than the solvent.

[0068] The thermosetting adhesive layer 3 and the thermosetting adhesive may further contain other components such as an ion trapper, an antioxidant, a silane coupling agent, a titanium coupling agent, and a leveling agent. These may be used alone or in combination of two or more.

[0069] The thermosetting adhesive for forming the thermosetting adhesive layer 3 may further contain a solvent that dissolves or disperses each component. A film-like thermosetting adhesive can be produced by applying a solvent-containing thermosetting adhesive (resin varnish) to a substrate film and drying the coating.

[0070] The solvent used in preparing the resin varnish is selected from those capable of uniformly dissolving or dispersing each component. The solvent can 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.

[0071] Examples of the substrate film include polyolefin films such as polypropylene film and polymethylpentene film, polyester films such as polyethylene terephthalate film and polyethylene naphthalate film, polyimide film, and polyetherimide film. The substrate film may be a single-layer film made of these films, or a multilayer film made of two or more types of films.

[0072] When the thermosetting adhesive layer 3 has high fluidity near the onset temperature, good conductivity is likely to be ensured. Therefore, the thermosetting adhesive layer 3 may exhibit a shear viscosity of 10,000 Pa·s or less, 9,000 Pa·s or less, 8,000 Pa·s or less, 7,000 Pa·s or less, 6,000 Pa·s or less, 5,000 Pa·s or less, 4,000 Pa·s or less, 3,000 Pa·s or less, or 2,000 Pa·s or less at a temperature 20°C lower than the onset temperature. The thermosetting adhesive layer 3 may exhibit a shear viscosity of 500 Pa·s or more, or 1,000 Pa·s or more at a temperature 20°C lower than the onset temperature.

[0073] The shear viscosity of the thermosetting adhesive layer 3 at 40° C. may be 10,000 Pa·s or more, 200,000 Pa·s or less, or 150,000 Pa·s or less.

[0074] The minimum shear viscosity (minimum melt viscosity) of the thermosetting adhesive layer 3 may be 500 Pa·s or more and 3000 Pa·s or less, or 800 Pa·s or more and 2500 Pa·s or less. When the minimum melt viscosity of the thermosetting adhesive layer 3 is in this range, voids tend to be less likely to remain in the adhesive layer. Furthermore, in the temporary pressure-bonding step, the thermosetting adhesive tends to be easily and sufficiently removed from between the connected portions.

[0075] The shear viscosity of the thermosetting adhesive layer 3 at each temperature and the minimum shear viscosity value can be values ​​read from a viscosity curve showing the relationship between shear viscosity (complex viscosity) and temperature obtained when measuring the viscoelasticity of a sample of the thermosetting adhesive layer 3 under conditions of a heating rate of 10°C / min, a frequency of 10 Hz, and a strain of 1%. The sample for viscoelasticity measurement may be, for example, a laminate having a thickness of 300 to 450 μm obtained by laminating multiple thermosetting adhesive layers. The viscosity measurement device may be, for example, an ARES manufactured by TA Instruments.

[0076] The shear viscosity of the thermosetting adhesive layer 3 can be adjusted within a desired range, for example, by adjusting the type and content of the polymer component or filler.

[0077] The gel time of the thermosetting adhesive layer 3 may be 10 seconds or more and 30 seconds or less at 200°C. Having the gel time in this range can contribute to suppressing residual voids and improving 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 gels. The gel time of the thermosetting adhesive layer 3 can be adjusted by the type and content of the curing agent, etc.

[0078] The present invention is not limited to the following examples. 1. Raw materials (a) Epoxy resin - Multifunctional solid epoxy resin having a triphenolmethane skeleton (EP1032H60, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 800 to 2000) - Bisphenol F type liquid epoxy resin (YL983U, manufactured by Mitsubishi Chemical Corporation, molecular weight: approximately 336) - Flexible semi-solid epoxy resin (YX7110B80, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 1000 to 5000) (b) Hardener - 2,4-Diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (2MAOK-PW, manufactured by Shikoku Chemicals Corporation) (c) Polymer component - Phenoxy resin (FX-293, manufactured by Nippon Steel Chemical & Material Co., Ltd., Tg: approximately 160°C, weight average molecular weight: 40,000 to 50,000) (d) Fluxing agent Glutaric acid (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: about 98°C) (e) Filler Inorganic filler Silica filler (SE2030, manufactured by Admatechs Co., Ltd., average particle size: 500 nm) Epoxy silane surface-treated silica filler (SE2030, manufactured by Admatechs Co., Ltd., average particle size: about 500 nm) Methacrylic surface-treated nano silica filler (YA050C, manufactured by Admatechs Co., Ltd., average particle size: about 50 nm) Organic filler Resin filler (EXL-2655, manufactured by Dow Chemical Japan, core-shell type organic fine particles)

[0079] 2. Preparation of film-like thermosetting adhesives Two types of film-like thermosetting adhesives A and B (thickness 40 μm) were prepared by applying a resin varnish containing each raw material in the ratio (parts by mass) shown in Table 1 to a substrate film and drying the coating.

[0080] DSC (Differential Scanning Calorimetry) DSC was measured for thermosetting adhesive A or B under the following conditions: Sample amount: 10 mg Heating rate: 10°C / min Air or nitrogen atmosphere The onset temperature, peak temperature, and heat generation amount were determined for the exothermic peak that showed the largest heat generation amount in the obtained DSC curve. Thermosetting adhesives A and B showed an integrated exothermic peak including two maximum points. The onset temperature was determined as the temperature at the intersection of the tangent to the curve at the position where the gradient of the exothermic peak curve, on the lower temperature side of the two maximum points, is greatest and the extension of the baseline of the DSC curve. The peak temperature is the temperature at the highest of the two maximum points.

[0081] Reaction rate Thermosetting adhesives A and B were heated at 150°C or 170°C for 30 seconds. After heating, the thermosetting adhesives were measured by DSC under the same conditions as above, and the calorific value Q1 of the exothermic peak was determined. The reaction rate was calculated from Q1 and the calorific value Q0 of the thermosetting adhesive before heating using the following formula: Reaction rate (%) = {(Q0 - Q1) / Q0} x 100

[0082] Shear Viscosity The thermosetting adhesive was laminated using a laminator to form a laminate with a thickness of 500 μm or more. A measurement sample having a size of 10.0 mm x 10.0 mm was cut out from the laminate. The shear viscosity (viscosity coefficient) of the measurement sample was measured under the following conditions using a viscoelasticity measuring device (trade name: ARES-G2, manufactured by TA Instruments). The shear viscosity and the minimum melt viscosity (minimum melt viscosity) at 40°C, 80°C, 130°C, 150°C, or 160°C were determined from a viscosity curve showing the relationship between shear viscosity and temperature. Table 1 also shows the temperature at which the minimum melt viscosity was observed. Mode: Shear Heating rate: 10°C / min Frequency: 10 Hz Strain: 1%

[0083]

[0084] 3. Manufacturing of Semiconductor Device Pre-Compression Bonding Step The following first semiconductor chip and second semiconductor chip were prepared. First semiconductor chip: A semiconductor chip having Cu pillars and solder bumps (melting point: approximately 217°C) containing Sn-Ag alloy on the Cu pillars, with connecting portions provided at different pitches along the periphery and inside the chip body (size: 7.3 mm square, thickness: 50 μm, total height of Cu pillars and Sn-Ag solder: approximately 45 μm, number of bumps: 1048 pins, bump pitch along the periphery: 80 μm, inner bump pitch: 300 μm, product name: WALTS-TEG CC80, manufactured by Waltz Corporation). Second semiconductor chip: A second semiconductor chip having Ni-plated and Au-plated (melting point: approximately 1065°C) connecting portions provided at different pitches along the periphery and inside the chip body (chip size: 10 mm square, thickness: 100 μm, product name: WALTS-TEG IP80, manufactured by Waltz Corporation).

[0085] A film of thermosetting adhesive A or B cut to a size of 7.3 mm square was attached to the connection surface of the first semiconductor chip, where the connection portion was provided. The first semiconductor chip with the thermosetting adhesive attached was picked up using the pressure head of a flip-chip bonder (FCB3, manufactured by Panasonic Corporation). The picked-up first semiconductor chip was placed on a second semiconductor chip placed on a stage, with the thermosetting adhesive sandwiched between the first and second semiconductor chips. The resulting stack was then heated and pressed using the pressure head of the flip-chip bonder, thereby obtaining a temporary pressure-bonded body. The temporary pressure-bonded bodies were fabricated under several conditions of temperature, time, and pressure shown in Table 2. The temperature is the set temperature of the pressure head, and the pressure is the load applied to the entire first semiconductor chip by the pressure head.

[0086] Main pressure bonding process Each pre-bonded body was heated in a heating furnace (pressure reflow machine, VPF300HP, manufactured by Synapex Co., Ltd.) under a pressurized atmosphere of 0.8 MPa to form a connection body (semiconductor device) for evaluation having a first semiconductor chip and a second semiconductor chip. The temperature of the pressurized atmosphere was changed under the following temperature conditions C1 or C2. C1: Heating at 3 ° C / sec, and then holding at 260 ° C (main pressure bonding temperature) for 10 minutes (time at temperature above the melting point of the solder containing Sn-Ag alloy: approximately 630 seconds) 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 pressure bonding temperature) for 0.1 seconds (time at temperature above the melting point of the solder containing Sn-Ag alloy: approximately 30 seconds)

[0087] 4. Evaluation (1) Connectivity Conduction The conduction state between the connections of the temporary crimped body and the connection body was measured using a digital multimeter (CDM-09N, manufactured by Custom Co., Ltd.). OK: Conduction was confirmed at the connection on the inner circumference. NG: Conduction was not confirmed at the connection on the inner circumference.

[0088] Solder condition The cross section of the connection was observed using an SEM (scanning electron microscope SU1510, manufactured by Hitachi High-Tech Corporation). The solder condition at the cross section of the connection was evaluated according to the following criteria: A: No defects or voids B: Defects or voids present C: Solder crushed D: Poor connection (connections not in contact with each other) Figure 5 is a photograph of the connection in the connection body of Example 4, where the solder condition was A. Figure 6 is a photograph of the connection in the connection body of Example 2, where the solder condition was B. Figure 7 is a photograph of the connection in the connection body of Comparative Example 2, where the solder condition was C. Figure 8 is a photograph of the connection in the connection body of Comparative Example 1, where the solder conditions were C and D.

[0089] (2) Voids The state of remaining voids inside the connection body after full pressure bonding was evaluated using SAM (ultrasound digital imaging diagnostic device IS-350, manufactured by Insight Co., Ltd.). It was confirmed that the voids had been properly removed in all connection bodies.

[0090]

[0091] As shown in Table 2, it was confirmed that by combining a pre-pressing process involving heating to a pre-pressing temperature equal to or higher than the onset temperature and a main pressure bonding process involving pressurization in a pressurized atmosphere at a low pressure of 1.50 MPa or less, deformation of the connection (solder crushing) can be suppressed while ensuring good conductivity.

[0092] 1...first circuit member, 2...second circuit member, 3...thermosetting adhesive layer, 11...metal pillar, 12...bump, 15...first connection portion, 25...second connection portion, 41, 42...pressure member, 50...heating furnace, 100...laminated body, 101...temporarily pressure-bonded body, 102...connection body (semiconductor device).

Claims

1. A method for manufacturing a semiconductor device, comprising: heating and pressurizing a laminate having a first circuit member having a first connecting portion containing a first metallic material, a second circuit member having a second connecting portion containing a second metallic material, and a thermosetting adhesive layer, with the thermosetting adhesive layer being interposed between the first circuit member and the second circuit member, by a pair of opposing pressing members, thereby forming a temporary pressure-bonded body in which the first connecting portion and the second connecting portion are in contact; and heating the temporary pressure-bonded body to a predetermined full pressure bonding temperature in a pressurized atmosphere, thereby forming a connection body in which the first connecting portion and the second connecting portion are electrically connected by metallic bonding between the first metallic material and the second metallic material, wherein the first circuit member is a semiconductor chip or a semiconductor wafer, and the second circuit member is a wired circuit board, a semiconductor chip, or a semiconductor wafer; and the laminate is pressed by the pair of pressing members at a predetermined pressure of 1.50 MPa or less, A method in which, during part or all of the time while the laminate is heated and pressurized by the pair of pressing members, at least one of the pair of pressing members is heated to a predetermined pre-compression temperature, the pre-compression temperature being a temperature that is equal to or higher than the onset temperature of the thermosetting adhesive layer and lower than the main compression temperature, the onset temperature being the onset temperature of the heat generation peak showing the largest heat generation amount in a DSC curve obtained by differential scanning calorimetry under conditions in which a sample of the thermosetting adhesive layer is heated at a heating rate of 10°C / min, and the main compression temperature being a temperature that is equal to or higher than at least one of the melting point of the first metal material or the melting point of the second metal material.

2. The method according to claim 1, wherein the predetermined pressure is greater than or equal to 0.94 MPa and less than or equal to 1.50 MPa.

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

4. The method according to claim 1, wherein the laminate is heated and pressed by the pair of pressing members for 5 seconds or less.

5. The method according to claim 1, wherein the thermosetting adhesive layer exhibits a shear viscosity of 10,000 Pa·s or less at a temperature 20° C. lower than the onset 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 during which the pre-bonded body is heated under the pressurized atmosphere to a temperature equal to or higher than at least one of the melting point of the first metal material and the melting point of the second metal material is 60 seconds or less.

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

8. The method of claim 1, wherein the thermosetting adhesive layer comprises: 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.

9. The method of claim 8, wherein the polymeric component has a glass transition temperature of 200° C. or less.

10. The method of claim 1, wherein the thermosetting adhesive layer exhibits a shear viscosity of 10,000 Pa·s or greater at 40°C.

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