Method for manufacturing joined body

Abstract

The present invention addresses the problem of providing a method for manufacturing a joined body, with which it is possible to achieve a joined body that has a low conduction resistance and a high joining strength. A method for manufacturing a joined body according to the present invention includes a joining step for forming a joined body by joining an anisotropic conductive joining member and an electrode member. The anisotropic conductive joining member has: an insulating base material that is formed of an inorganic material; and a plurality of conduction paths that penetrate the insulating base material in the thickness direction, and are provided so as to be insulated from each other, while being formed of conductive members. Each of the conduction paths has a protruding portion that protrudes from at least one surface of the insulating base material. The joining step includes a process for performing heating in the presence of 2% by volume or more of formic acid, in a state in which the protruding portion of each conduction path and the electrode member are in contact with each other.

Description

Manufacturing method of the bonded body

[0001] The present invention relates to a method for producing a bonded body.

[0002] Metal-filled microstructures (devices) formed by filling micropores in an insulating substrate with metal have recently attracted attention in the field of nanotechnology, and are expected to be used, for example, as anisotropically conductive bonding materials. This anisotropically conductive bonding material can be inserted between an electronic component such as a semiconductor element and a circuit board and electrically connected therebetween simply by applying pressure. Therefore, it is widely used as an electrical connection material for electronic components such as semiconductor elements, and as an inspection connector for functional testing. In particular, electronic components such as semiconductor elements are being significantly downsized. Conventional methods for directly connecting a wiring board, such as wire bonding, flip-chip bonding, and thermocompression bonding, cannot adequately ensure connection stability. Therefore, anisotropically conductive bonding materials are attracting attention as electronic connection materials.

[0003] As a microstructure that can be used for such an anisotropic conductive joining member, for example, Patent Document 1 discloses a "1×10 ６ ~1 x 10 １０ / mm ２ The document describes a microstructure comprising an insulating substrate having through micropores with a pore diameter of 10 to 500 nm at a density of 1000 nm, wherein the through micropores are filled with a metal at a filling rate of 30% or more, and a polymer layer is provided on at least one surface of the insulating substrate ([Claim 1]), and also describes that when protruding portions of the filled metal (conductive paths) in the microstructure are joined to connecting wiring (electrode members) of an electronic component by thermocompression bonding, the polymer layer reinforces the bond (

[0021] [Fig. 1]).

[0004] JP 2010-067589 A

[0005] The present inventors have found that when the microstructure described in Patent Document 1 is used for bonding without using a polymer layer in order to reduce the electrical resistance (conduction resistance) after bonding, there is room for improvement in the conduction resistance and the bonding strength may also be poor.

[0006] Therefore, an object of the present invention is to provide a method for producing a bonded body that can provide a bonded body having low electrical resistance and high bonding strength.

[0007] As a result of intensive research to achieve the above object, the present inventors have found that a bonded body having low electrical resistance and high bonding strength can be produced by a bonding step of bonding an anisotropic conductive bonding member and an electrode member, which includes a heating treatment in the presence of 2% by volume or more of formic acid while the protruding portion of the conductive path is in contact with the electrode member, and have completed the present invention. That is, the present inventors have found that the above object can be achieved by the following configuration.

[0008] [1] A method for producing a bonded body, the method including a bonding step of bonding an anisotropically conductive bonding member and an electrode member to produce a bonded body, the anisotropically conductive bonding member having an insulating base material made of an inorganic material and a plurality of conductive paths made of a conductive member penetrating the insulating base material in a thickness direction and insulated from one another, each conductive path having a protruding portion protruding from at least one surface of the insulating base material, the bonding step including a heating treatment in the presence of 2% by volume or more of formic acid while the protruding portion of each conductive path is in contact with the electrode member. [2] A method for producing a bonded body according to [1], wherein the heating temperature in the bonding step is 150 to 250°C. [3] A method for producing a bonded body according to [1] or [2], wherein the heating time in the bonding step is 3 minutes or more. [4] A method for producing a bonded body according to any one of [1] to [3], wherein the arithmetic mean height of the protruding portion of each conductive path is 100 nm to 5,000 nm. [5] The method for producing a joined body according to any one of [1] to [4], wherein the concentration of formic acid in the joining step is 15% by volume or less. [6] The method for producing a joined body according to any one of [1] to [5], further comprising a temporary joining step of temporarily joining an anisotropically conductive joining member and an electrode member before the joining step. [7] The method for producing a joined body according to any one of [1] to [6], wherein the conductive path contains copper. [8] The method for producing a joined body according to any one of [1] to [7], wherein the insulating base material contains an anodized aluminum film.

[0009] As will be described below, the present invention can provide a method for producing a bonded body that can provide a bonded body having low electrical resistance and high bonding strength.

[0010] FIG. 1 is a front view of a schematic diagram showing an example of a preferred embodiment of an anisotropically conductive bonding member used in the method for manufacturing a bonded body of the present invention. FIG. 2 is a cross-sectional view taken along the section line IB-IB in FIG. 1. FIG. 3 is a graph showing a first example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention. FIG. 4 is a graph showing a second example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention. FIG. 5 is a graph showing a third example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention. FIG. 6 is a graph showing a fourth example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention. FIG. 7 is a graph showing a fifth example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention. FIG. 8 is a graph showing a sixth example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention. FIG. 9 is a graph showing a seventh example of bonding conditions in the bonding step of the method for manufacturing a bonded body of the present invention.

[0011] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the upper and lower limits. In this specification, the upper or lower limit of a numerical range described in a stepwise manner may be replaced with the upper or lower limit of another stepwise manner. In this specification, the upper or lower limit of a numerical range described in a stepwise manner may be replaced with a value shown in the Examples. In this specification, each component may be a single substance corresponding to the component, or two or more substances may be used in combination. When two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified.

[0012] [Method for Manufacturing Bonded Body] The method for manufacturing a bonded body of the present invention (hereinafter also referred to as "the manufacturing method of the present invention") includes a bonding step of bonding an anisotropically conductive bonding member and an electrode member to produce a bonded body. The anisotropically conductive bonding member includes an insulating base material made of an inorganic material and a plurality of conductive paths made of a conductive member that penetrate the insulating base material in the thickness direction and are insulated from each other, and each conductive path has a protruding portion that protrudes from at least one surface of the insulating base material. The bonding step includes a treatment of heating the protruding portions of each conductive path and the electrode member in contact with each other in the presence of 2% or more by volume of formic acid.

[0013] As described above, in the present invention, the bonding step of bonding an anisotropic conductive bonding member and an electrode member to produce a bonded body includes a heating process in the presence of 2% by volume or more of formic acid while the protruding portions of the conductive paths are in contact with the electrode member, thereby producing a bonded body with low electrical resistance and high bonding strength. The mechanism behind this is not clear in detail, but is presumed to be as follows. First, the electrical resistance increases as oxidation progresses on the surface of the protruding portions of the conductive paths over time. Therefore, in the present invention, the bonding step includes a heating process in the presence of 2% by volume or more of formic acid while the protruding portions of the conductive paths are in contact with the electrode member, and the formic acid functions as a reducing gas, thereby suppressing oxidation of the surface of the protruding portions, thereby producing a bonded body with low electrical resistance and high bonding strength.

[0014] [Anisotropic conductive bonding member] Next, the configuration of the anisotropic conductive bonding member used in the manufacturing method of the present invention will be described with reference to Figures 1 and 2. The anisotropic conductive bonding member 1 shown in Figures 1 and 2 has an insulating substrate 2 and a plurality of conductive paths 3 made of a conductive material. As shown in Figures 1 and 2, the conductive paths 3 are insulated from each other and penetrate the insulating substrate 2 in the thickness direction Z (Z1: the direction from the back surface to the front surface in Figure 1, Z2: the direction from the front surface to the back surface in Figure 1). As shown in Figure 2, the conductive paths 3 have protruding portions 3a and 3b protruding from the surfaces 2a and 2b of the insulating substrate 2. Here, "insulated from each other" means that the conductive paths present inside the insulating substrate (thickness direction) are insulated from each other inside the insulating substrate.

[0015] <Insulating substrate> The insulating substrate of the anisotropically conductive bonding member is made of an inorganic material and has an electrical resistivity (10 １４ There are no particular limitations on the insulating base material as long as it has a resistivity of about Ω cm. Note that the phrase "made of an inorganic material" does not limit the insulating base material to one made of only inorganic materials, but rather refers to an insulating base material whose main component is an inorganic material (50 mass % or more).

[0016] Examples of the insulating substrate include a metal oxide substrate, a metal nitride substrate, a glass substrate, a ceramic substrate (e.g., silicon carbide, silicon nitride, etc.), a carbon substrate (e.g., diamond-like carbon, etc.), a polyimide substrate, and composite materials thereof. The insulating substrate may also be a material in which a film is formed on an organic material having through holes with an inorganic material containing 50 mass % or more of a ceramic material or a carbon material.

[0017] In the present invention, the insulating substrate is preferably a metal oxide substrate, more preferably an anodized film of a valve metal, because micropores having a desired average opening diameter are formed as through-holes, and the conductive paths described below are easily formed.Here, specific examples of the valve metal include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, etc.Among these, an anodized film of aluminum (substrate) is preferred because it has good dimensional stability and is relatively inexpensive.

[0018] In the present invention, the thickness of the insulating substrate (the portion indicated by reference numeral 6 in FIG. 2) is preferably 1 μm to 1000 μm, more preferably 5 μm to 500 μm, and even more preferably 10 μm to 300 μm. When the thickness of the insulating substrate is within this range, the insulating substrate becomes easy to handle. Here, the thickness of the insulating substrate refers to the average value of thicknesses measured at 10 points when a cross section of an anisotropic conductive bonding member is observed with a field emission scanning electron microscope.

[0019] In the present invention, the spacing between the conductive paths in the insulating substrate is preferably 5 nm to 800 nm, more preferably 10 nm to 200 nm, and even more preferably 20 nm to 60 nm. When the spacing between the conductive paths in the insulating substrate is within this range, the insulating substrate functions satisfactorily as an insulating partition wall. Here, the spacing between the conductive paths refers to the width between adjacent conductive paths (the portion indicated by reference numeral 7 in FIG. 2 ), and refers to the average value of the width between adjacent conductive paths measured at 10 points when the cross section of the metal-filled microstructure is observed at 200,000 times magnification using a field emission scanning electron microscope.

[0020] The conductive paths of the anisotropically conductive bonding member are made of conductive materials and extend through the insulating base material in the thickness direction, are insulated from one another, and have protruding portions that protrude from the surface of the insulating base material.

[0021] (Conductive Member) The conductive member constituting the conductive path has an electrical resistivity of 10３ There are no particular limitations on the material as long as it has a resistivity of Ω cm or less, and specific examples thereof include gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni), indium-doped tin oxide (ITO), etc. Among these, from the viewpoint of electrical conductivity, copper, gold, aluminum, and nickel are preferred, copper and gold are more preferred, and copper is even more preferred.

[0022] (Protruding Portion) The protruding portion of the conductive path is a portion of the conductive path that protrudes from the surface of the insulating substrate.

[0023] In the present invention, the aspect ratio of the protruding portion of the conductive path (height of the protruding portion / diameter of the protruding portion) is preferably 0.5 or more and less than 50, more preferably 0.8 to 20, and even more preferably 1 to 10, for the reason that sufficient insulation in the planar direction can be ensured if the protruding portion is crushed when joining to an electrode member described later.

[0024] Furthermore, in the present invention, the arithmetic mean height of the protruding portions of the conductive paths is preferably 100 nm to 5000 nm, more preferably 100 to 2000 nm, and even more preferably 200 to 1000 nm, because this results in lower electrical resistance. Similarly, the diameter of the protruding portions of the conductive paths is preferably greater than 5 nm and not greater than 10 μm, more preferably 20 nm to 1000 nm. Here, the height of the protruding portions of the conductive paths refers to the average value obtained by observing the cross section of the metal-filled microstructure with a field emission scanning electron microscope at 20,000x magnification and measuring the height of the protruding portions of the conductive paths at 10 points. Similarly, the diameter of the protruding portions of the conductive paths refers to the average value obtained by observing the cross section of the metal-filled microstructure with a field emission scanning electron microscope and measuring the diameter of the protruding portions of the conductive paths at 10 points.

[0025] <Other Shapes> The conductive paths are columnar, and the diameter thereof (the portion indicated by reference numeral 8 in FIG. 2) is preferably more than 5 nm and not more than 10 μm, similar to the diameter of the protruding portion, and more preferably 20 nm to 1000 nm.

[0026] The conductive paths are insulated from one another by the insulating substrate, and their density is 20,000 / mm ２ It is preferable that the density is 2 million / mm or more. ２ More preferably, it is 10 million particles / mm or more. ２ More preferably, it is 50 million particles / mm or more. ２ It is particularly preferable that the number of particles is 100 million / mm or more. ２ More preferably, it is equal to or greater than this.

[0027] Furthermore, the center-to-center distance between adjacent conductive paths (the portion indicated by reference numeral 9 in FIGS. 1 and 2) is preferably 20 nm to 500 nm, more preferably 40 nm to 200 nm, and even more preferably 50 nm to 140 nm.

[0028] [Electrode Member] The electrode member used in the manufacturing method of the present invention is not particularly limited as long as it has an electrode. Examples of the electrode member include electronic components such as semiconductor elements, semiconductor devices, printed wiring boards, and printed circuit boards.

[0029] <Semiconductor Element> In semiconductor elements, the functions of the semiconductor element are distinguished by the operation of the semiconductor element. Examples of semiconductor functions include calculations such as a central processing unit (CPU) or a graphics processing unit (GPU), storage such as a memory, conversion such as a converter, filtering, and sensing. When these functions are integrated into a single chip or unit, the functions of the integrated chip are identified. When the identified functions are different, the semiconductor elements are different.

[0030] Specific examples of such semiconductor elements include logic LSIs (Large Scale Integration), ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), ASSPs (Application Specific Standard Products), microprocessors (e.g., CPUs, GPUs, etc.), memories (e.g., DRAMs (Dynamic Random Access Memory), SRAMs (Static Random Access Memory), HMCs (Hybrid Memory Cubes), MRAMs (Magnetic RAMs), PCMs (Phase-Change Memory), ReRAMs (Resistive RAMs), FeRAMs (Ferroelectric RAMs), flash memories, etc.), LEDs (Light Emitting Diodes), power semiconductor devices, analog ICs (Integrated Circuits), DC (Direct Current)-DC (Direct Current) converters, insulated gate bipolar transistors (IGBTs), MEMS (Micro Electro Mechanical Systems) such as acceleration sensors, pressure sensors, vibrators, and gyro sensors, GPSs (Global Positioning Systems), FMs (Frequency Modulation Modulation). Modulation), NFC (Nearfield communication), RFEM (RF Expansion Module), MMIC (Monolithic Microwave Integrated Circuit), WLAN (Wireless Local Area Network), discrete elements, BSI (Back Side Illumination), CIS (Contact Image Sensor), camera module, passive device, SAW (Surface Acoustic Wave) filter, RF (Radio Frequency) filter, RFIPD (Radio Frequency Integrated PassiveDevices), BB (Broadband), etc. The semiconductor element may also have a TSV (Through Silicon Via) or a TGV (Through-Glass Via).

[0031] The composition of the semiconductor constituting the semiconductor element is not particularly limited, and examples of the semiconductor composition include diamond, silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide, and silicon-on-insulator (SOI).

[0032] <Semiconductor Device> A semiconductor device is a collection of multiple semiconductor elements that perform a specific function, but also includes devices that simply transmit electrical signals. A semiconductor device may also be, for example, a logic device with a two-dimensional (2D), two-and-a-half-dimensional (2.5D), or three-dimensional (3D) architecture. A semiconductor device may also be, for example, a DRAM stack in which multiple DRAMs are stacked, or a configuration in which a DRAM stack and a logic LSI are stacked.

[0033] The semiconductor device may also include a printed wiring board, a heat sink, etc. The semiconductor device may also include digital, analog, or mixed-signal peripheral circuits in addition to the semiconductor elements described above. More specifically, the semiconductor device may include a peripheral device layer having one or more of a page buffer, a row decoder, a column decoder, a sense amplifier, a driver, a charge pump, a transistor, a diode, a resistor, or a capacitor.

[0034] Furthermore, the semiconductor device may have an element region in addition to the semiconductor elements described above. The element region is a region in which various element component circuits, etc., for functioning as electronic elements are formed. The element region may include, for example, a region in which a memory circuit such as a flash memory, a logic circuit such as a microprocessor and an FPGA (field-programmable gate array), etc., is formed, and a region in which a communication module such as a wireless tag and wiring are formed. In addition to the above, a MEMS may be formed in the element region. Examples of MEMS include sensors, actuators, and antennas. Examples of sensors include various sensors for acceleration, sound, light, etc.

[0035] [Steps in the manufacturing method] The manufacturing method of the present invention is not particularly limited as long as the joining step of joining the anisotropically conductive joining member and the electrode member includes a heating treatment in the presence of 2 volume % or more of formic acid while the protruding portion of the conductive path and the electrode member are in contact with each other. Note that, hereinafter, the joining of the anisotropically conductive joining member and the electrode member in the joining step is also referred to as "main joining." Furthermore, the manufacturing method of the present invention preferably includes a temporary joining step of temporarily joining the anisotropically conductive joining member and the electrode member before the joining step.

[0036] <Temporary Bonding Process> The term "temporary bonding" in the temporary bonding process refers to holding the anisotropically conductive bonding member on the objects to be joined in an aligned state with respect to the objects to be joined (i.e., temporarily fixing the anisotropically conductive bonding member until the joining process described below). Therefore, the temporary bonding maintains the aligned state but is not permanently fixed. When the anisotropically conductive bonding member and the electrode members to be joined are temporarily fixed, the anisotropically conductive bonding member is held aligned with the electrode members. The temporary bonding process is carried out by bringing at least two members into close contact with each other. In this case, the pressure conditions are not particularly limited, but are preferably 10 MPa or less, more preferably 5 MPa or less, and particularly preferably 1 MPa or less. Similarly, the temperature conditions in the temporary bonding process are not particularly limited, but are preferably 0°C to 300°C, more preferably 10°C to 200°C, and particularly preferably room temperature (23°C) to 100°C. Equipment from companies such as Toray Engineering, Shibuya Kogyo Co., Ltd., Shinkawa Corporation, and Yamaha Motor Co., Ltd. can be used for the temporary bonding process.

[0037] <Bonding process> The above-mentioned bonding process can be carried out in any suitable manner, as long as it includes a heating process in the presence of 2% by volume or more of formic acid while the protruding portion of the conductive path and the electrode member are in contact with each other.

[0038] The atmosphere for this bonding is not particularly limited as long as it contains 2% or more by volume of formic acid. It may be air, an inert gas (e.g., nitrogen gas, argon gas, etc.), a reducing gas (e.g., a carboxylic acid other than formic acid, hydrogen, etc.), or a mixed gas atmosphere of an inert gas and a reducing gas. Techniques using such gases include solder fusion bonding techniques and bonding techniques using fine metal particles. For example, formic acid can be introduced together with an inert gas after evacuating the gas inside the container. In the present invention, Amager's law is assumed to hold true for the volume ratio of each component in the atmosphere. The amount of each component can be quantified using a device such as gas chromatography.

[0039] The concentration of formic acid in the atmosphere for this bonding is 2% by volume or more, and the upper limit is preferably the explosion limit or less, more preferably 17% by volume or less, specifically, 2 to 16% by volume, more preferably 2 to 15% by volume.

[0040] In the present invention, the bonding may be performed under a reduced pressure atmosphere. The pressure under the reduced pressure atmosphere is not particularly limited, but it is preferably 10 ５ Pa to 10 －５ Pa, and preferably 10 ２ Pa to 10 －５ It is more preferable that the pressure is 100 Pa. The heating may be performed in a vacuum atmosphere.

[0041] In the present invention, the heating temperature in this bonding is not particularly limited, but is preferably 150 to 250°C, and more preferably 150 to 200°C, because this results in lower electrical resistance. The temperature rise rate during heating can be selected from 10°C / min to 10°C / sec depending on the performance of the heating stage or the heating method. It is also possible to heat in a stepwise manner, dividing the materials into several stages and successively increasing the heating temperature to bond them.

[0042] In the present invention, the pressure conditions for this joining are not particularly limited, but are preferably 30 MPa or less, and more preferably 0.1 MPa to 20 MPa. The maximum load under the pressure conditions is preferably 1 MN or less, and more preferably 0.1 MN or less. The pressure method can be selected to apply pressure quickly or in steps depending on the physical properties such as the strength of the objects to be joined.

[0043] Furthermore, in the present invention, the heating time for this bonding is not particularly limited, but is preferably 3 minutes or more, and more preferably 3 to 10 minutes, because this reduces the electrical resistance and increases the bonding strength.

[0044] The apparatus used for the above-mentioned main bonding may be, for example, wafer bonding apparatus from various companies such as Mitsubishi Heavy Industries Machine Tools, Bondtech, PMT Co., Ltd., Ayumi Industries, Tokyo Electron (TEL), EVG, SUSS Microtec K.K. (SUSS), and Musashino Engineering.

[0045] In the present invention, the atmosphere, heating and pressurization durations, and the order of these can be modified as needed. For example, a procedure can be implemented in which a first pressurization step is performed after a vacuum is established, followed by heating and raising the temperature, followed by a second pressurization step, which is maintained for a certain period of time, followed by unloading and cooling, followed by returning to atmospheric pressure once the temperature has reached a certain level. This procedure can be rearranged in various ways, such as applying pressure in atmospheric air, followed by heating in a vacuum, or by performing vacuum, pressurization, and heating all at once. Examples of these combinations are shown in Figures 3 to 9. Furthermore, using a mechanism that individually controls the in-plane pressure and heat distribution during bonding can improve bonding yield. Similar modifications can be made to the temporary bonding process; for example, performing it in an inert atmosphere can suppress oxidation of the electrode surface of the semiconductor element. Furthermore, bonding can be performed while applying ultrasonic waves.

[0046] FIGS. 3 to 9 are graphs showing first to seventh examples of bonding conditions for the bonding step of the method for manufacturing a bonded body of the present invention. FIGS. 3 to 9 show the atmosphere, heating temperature, applied pressure (load), and processing time during bonding, where V indicates the degree of vacuum. L indicates the load, and T indicates the temperature. A high degree of vacuum in FIGS. 3 to 9 indicates a low pressure. Regarding the atmosphere, heating temperature, and load during bonding, for example, as shown in FIGS. 3 to 5, the temperature may be increased after applying a load under reduced pressure. Alternatively, as shown in FIGS. 6, 8, and 9, the timing of applying the load and the timing of increasing the temperature may be synchronized. As shown in FIG. 7, the temperature may be increased before applying the load. Alternatively, as shown in FIGS. 6 and 7, the timing of reducing the pressure and the timing of increasing the temperature may be synchronized. The temperature may be increased in a stepwise manner as shown in FIGS. 3, 4, and 8, or in two stages as shown in FIG. 9. The load may also be applied in a stepwise manner as shown in FIGS. 5 and 8. The pressure may be reduced before the load is applied as shown in Figures 3, 5, 7, 8 and 9, or the pressure may be reduced and the load may be applied at the same time as shown in Figures 4 and 6. In this case, the pressure is reduced and the bonding is performed simultaneously.

[0047] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0048] [Example 1] [Preparation of anisotropic conductive bonding member] <Preparation of aluminum substrate> A molten aluminum alloy containing 0.06% by mass of Si, 0.30% by mass of Fe, 0.005% by mass of Cu, 0.001% by mass of Mn, 0.001% by mass of Mg, 0.001% by mass of Zn, and 0.03% by mass of Ti, with the remainder being Al and inevitable impurities, was prepared. After molten aluminum alloy treatment and filtration, a 500 mm thick, 1200 mm wide ingot was produced by DC (Direct Chill) casting. Then, the surface was scraped off to an average thickness of 10 mm using a facing mill, and the ingot was soaked at 550 ° C for about 5 hours. When the temperature was reduced to 400 ° C, it was rolled into a 2.7 mm thick plate using a hot rolling mill. Further, the aluminum substrate was subjected to heat treatment at 500°C using a continuous annealing machine, and then cold-rolled to a thickness of 1.0 mm to obtain an aluminum substrate of JIS 1050. This aluminum substrate was formed into a wafer having a diameter of 200 mm (8 inches), and then subjected to the following treatments.

[0049] <Electrolytic Polishing Treatment> The above-mentioned aluminum substrate was subjected to electrolytic polishing treatment using an electrolytic polishing solution having the following composition under conditions of a voltage of 25 V, a solution temperature of 65°C, and a solution flow rate of 3.0 m / min. A carbon electrode was used as the cathode, and a GP0110-30R (manufactured by Takasago Machinery Co., Ltd.) was used as the power source. The flow rate of the electrolyte was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation). (Electrolytic Polishing Solution Composition) 85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 660 mL, pure water 160 mL, sulfuric acid 150 mL, and ethylene glycol 30 mL

[0050] <Anodizing Treatment Step> Next, the aluminum substrate after electrolytic polishing treatment was subjected to anodizing treatment by the self-ordering method according to the procedure described in JP 2007-204802 A. The aluminum substrate after electrolytic polishing treatment was subjected to a 5-hour pre-anodizing treatment in a 0.50 mol / L oxalic acid electrolytic solution under the conditions of a voltage of 40 V, a solution temperature of 16 ° C, and a solution flow rate of 3.0 m / min. Thereafter, the aluminum substrate after pre-anodizing treatment was subjected to a film removal treatment by immersing it in a mixed aqueous solution (liquid temperature: 50 ° C) of 0.2 mol / L chromic anhydride and 0.6 mol / L phosphoric acid for 12 hours. Thereafter, a re-anodizing treatment was performed for 3 hours and 45 minutes in a 0.50 mol / L oxalic acid electrolytic solution under the conditions of a voltage of 40 V, a solution temperature of 16 ° C, and a solution flow rate of 3.0 m / min, to obtain an anodized film with a film thickness of 30 μm. In both the pre-anodizing treatment and the re-anodizing treatment, a stainless steel electrode was used as the cathode, and a GP0110-30R power supply (manufactured by Takasago Machinery Co., Ltd.) was used. A NeoCool BD36 (manufactured by Yamato Scientific Co., Ltd.) was used as the cooling device, and a Pair Stirrer PS-100 (manufactured by EYELA Tokyo Rikakikai Co., Ltd.) was used as the stirring / heating device. Furthermore, the flow rate of the electrolyte was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE Corporation).

[0051] <Barrier Layer Removal Process> Next, using the same treatment solution and treatment conditions as those used in the anodizing process described above, an electrolytic treatment (electrolytic removal process) was performed while continuously decreasing the voltage from 40 V to 0 V at a voltage drop rate of 0.2 V / sec. Thereafter, an etching treatment (etching removal process) was performed by immersing the anodized film in an aqueous phosphoric acid solution (concentration: 5% by mass, solution temperature: 30°C) for 30 minutes, removing the barrier layer at the bottom of the micropores in the anodized film and exposing the aluminum through the micropores. The average opening diameter of the micropores present in the anodized film after the barrier layer removal process was 60 nm. The average opening diameter was calculated by taking surface photographs (magnification: 50,000x) using a field emission scanning electron microscope (FE-SEM) and measuring 50 points. The average thickness of the anodized film after the barrier layer removal process was 30 μm. The average thickness was calculated by cutting the anodized film in the thickness direction with a focused ion beam (FIB), taking surface photographs of the cross section with an FE-SEM (magnification: 50,000 times), and averaging the measurements at 10 points. The density of micropores in the anodized film was approximately 100 million / mm. ２ The micropore density was measured and calculated by the method described in paragraphs

[0168] and

[0169] of JP 2008-270158 A. The degree of ordering of the micropores present in the anodic oxide film was 92%. The degree of ordering was measured and calculated by the method described in paragraphs

[0024] to

[0027] of JP 2008-270158 A, using a FE-SEM to take a surface photograph (magnification: 20,000 times).

[0052] <Metal Filling Step> Next, electrolytic plating was performed using the aluminum substrate as the cathode and platinum as the cathode. Specifically, a copper plating solution having the composition shown below was used, and constant-current electrolysis was performed to produce a metal-filled microstructure in which copper was filled into the micropores. Here, constant-current electrolysis was performed using a plating device manufactured by Yamamoto Plating Tester Co., Ltd. and a power supply (HZ-3000) manufactured by Hokuto Denko Corporation. After confirming the deposition potential by performing cyclic voltammetry in the plating solution, the process was performed under the conditions shown below. (Copper Plating Solution Composition and Conditions) Copper sulfate 100 g / L Sulfuric acid 50 g / L Hydrochloric acid 15 g / L Temperature 25°C Current density 10 A / dm ２

[0053] <Polishing Step> Next, the surface of the metal-filled structure was subjected to a CMP (Chemical Mechanical Polishing) treatment, polishing 5 μm from the surface to smooth the surface. PNANERLITE-7000 manufactured by Fujimi Incorporated was used as the CMP slurry. The surface of the anodized film after the micropores were filled with metal was observed with an FE-SEM, and the presence or absence of metal sealing in 1,000 micropores was observed to calculate the sealing rate (number of sealed micropores / 1,000), which was 96%. Furthermore, the anodized film after the micropores were filled with metal was cut in the thickness direction with an FIB, and a surface photograph (magnification 50,000 times) of the cross section was taken with an FE-SEM to confirm the interior of the micropores. It was found that the interior of the sealed micropores was completely filled with metal.

[0054] <Substrate Removal Step> Next, the aluminum substrate was dissolved and removed by immersion in a 20% by mass aqueous solution of mercury chloride (mercury bicarbonate) at 20° C. for 3 hours, thereby producing a metal-filled microstructure.

[0055] <Polishing step> Next, the back surface of the metal-filled microstructure, i.e., the surface from which the aluminum substrate had been removed, was subjected to CMP (Chemical Mechanical Polishing) treatment to polish it by 5 μm, thereby smoothing the back surface of the metal-filled microstructure. As the CMP slurry, PNANERLITE-7000 manufactured by Fujimi Inc. was used.

[0056] <Trimming process> After the substrate removal process, the metal-filled microstructure was immersed in an aqueous sodium hydroxide solution (concentration: 5% by mass, liquid temperature: 20°C), and the immersion time was adjusted so that the height of the protruding parts was 500 nm, thereby selectively dissolving the surface of the aluminum anodized film.Then, the structure was washed with water and dried to produce an anisotropic conductive bonding member with protruding copper cylinders as conductive paths.

[0057] [Fabrication of Bonded Assembly (Bonding Process)] A TEG chip (Test Element Group chip) with Cu pads and an interposer were prepared. These included a daisy chain pattern for measuring conduction resistance and a comb-tooth pattern for measuring insulation resistance. The insulating layer was made of SiN. The TEG chip had a chip size of 8 mm square, and the ratio of electrode area (copper post) to chip area was 25%. The electrodes had a diameter of 5 μm and a height of 7 μm, and the thickness of the insulating layer between the electrodes was 2 μm. The TEG chip corresponds to the semiconductor member. Since the interposer included lead wiring around the periphery, a chip size of 10 mm square was prepared. Furthermore, when bonding, the TEG chip, the anisotropic conductive bonding material, and the interposer were stacked in this order, specifically, the protruding portions of the conductive paths on one surface of the anisotropic conductive bonding material were brought into contact with the electrodes of the TEG chip, and the protruding portions of the conductive paths on the other surface of the anisotropic conductive bonding material were brought into contact with the electrodes of the interposer, and then the stacked state was introduced into a chamber. Thereafter, the chamber was evacuated to remove 10% of the heat. ２The pressure was reduced to a pressure of 10 Pa or less. Formic acid and nitrogen were introduced into the chamber, and the gas in the chamber was sampled, and the amount of formic acid was quantified using gas chromatography. Next, the flow rate of formic acid was adjusted so that the amount of formic acid was 2% by volume. Next, the exhaust rate was adjusted to 1×10 ４ The pressure in the chamber was kept constant at 180°C for 5 minutes using a wafer bonding device manufactured by EVG. At this time, the TEG chip and the Cu pad of the interposer were aligned using alignment marks formed in advance on the corners of the chip to prevent misalignment.

[0058] [Comparative Examples 1 to 3 and Examples 2 to 19] Bonded bodies were produced in the same manner as in Example 1, except that the presence or absence of protruding portions of the conductive paths, the arithmetic mean height of the protruding portions of the conductive paths, the conductive path area ratio, the material of the conductive paths, the presence or absence of temporary bonding (100°C x 1 MPa x 3 min), the concentration of reducing gas (formic acid or hydrogen), the presence or absence of heating during bonding, the heating temperature, and the heating time were changed as shown in Tables 1 and 2. The arithmetic mean height of the protruding portions of the conductive paths was adjusted by the immersion time in an aqueous sodium hydroxide solution (concentration: 5% by mass, liquid temperature: 20°C) in the trimming step, and the conductive path area ratio was adjusted by the immersion time in an aqueous phosphoric acid solution (concentration: 5% by mass, liquid temperature: 30°C) used in the etching treatment in the barrier layer removal step.

[0059] [Resistance Evaluation] For each of the bonded structures produced in Examples 1 to 19 and Comparative Examples 1 to 3, a probe was brought into contact with the lead wiring pad of the daisy chain pattern portion of the interposer, and a conductivity evaluation was performed in the atmosphere. Resistance measurements were performed using a Keithley source meter as the measuring device. Based on the resistance value results, evaluation was performed according to the following criteria. The evaluation results are shown in Tables 1 and 2 below. <Evaluation criteria for conduction resistance> A: Resistance value less than 10 times the design resistance B: Resistance value 10 to 100 times the design resistance C: Resistance value 100 to 1000 times the design resistance D: Resistance value 1000 times or more the design resistance <Evaluation criteria for insulation resistance> A: Resistance value 1 GΩ or more B: Resistance value 1 MΩ to 1 GΩ C: Resistance value 1 KΩ to 1 MΩ D: Resistance value less than 1 KΩ

[0060] [Bonding Strength] The shear strength of each of the bonded structures produced in Examples 1 to 19 and Comparative Examples 1 to 3 was measured using a universal bond tester Dage-4000 (manufactured by Nordson Advanced Technologies Co., Ltd.). Next, the bonding strength per area of ​​the TEG chip was calculated from the obtained shear strength and evaluated according to the following criteria. The evaluation results are shown in Tables 1 and 2 below. A: Bonding strength of 20 MPa or more B: Bonding strength of 10 MPa or more but less than 20 MPa C: Bonding strength of less than 10 MPa

[0061]

[0062]

[0063] The results shown in Tables 1 and 2 above indicate that when there are no protruding portions in the conductive paths, the conduction resistance is high (Comparative Example 1). Furthermore, when the concentration of formic acid is 0.8% by volume, the conduction resistance is high and the bonding strength is poor (Comparative Example 2). Furthermore, when bonding is performed at room temperature (25°C) without heating, the conduction resistance is high and the bonding strength is poor (Comparative Example 3).

[0064] In contrast, it was found that when the conductive path has a protruding portion and the bonding step includes heating the protruding portion of the conductive path in contact with the electrode member in the presence of 2 volume % or more of formic acid, a bonded body with low electrical resistance and high bonding strength can be obtained (Examples 1 to 19). Furthermore, a comparison of Examples 1, 2, 8, and 9 revealed that the electrical resistance was further reduced when the heating temperature in the bonding step was 150 to 250°C. Furthermore, a comparison of Examples 1, 3, 10, and 11 revealed that the electrical resistance was further reduced and the bonding strength was further increased when the heating time in the bonding step was 3 minutes or more (particularly 3 to 10 minutes). Furthermore, a comparison of Examples 1, 4, 12, 13, and 14 revealed that the electrical resistance was further reduced when the arithmetic mean height of the protruding portion of the conductive path was 100 nm to 5000 nm.

[0065] REFERENCE SIGNS LIST 1 Anisotropic conductive bonding member 2 Insulating substrate 2a, 2b Surface of insulating substrate 3 Conductive path 3a, 3b Protruding portion of conductive path 6 Thickness of insulating substrate 7 Spacing between conductive paths 8 Diameter of conductive path 9 Center-to-center distance (pitch) of conductive paths

Claims

1. A method for producing a bonded body, comprising a bonding step of bonding an anisotropic conductive bonding member and an electrode member to produce a bonded body, wherein the anisotropic conductive bonding member comprises an insulating base material made of an inorganic material and a plurality of conductive paths made of a conductive member which penetrate the insulating base material in the thickness direction and are insulated from one another, each of the conductive paths having a protruding portion protruding from at least one surface of the insulating base material, and the bonding step comprises a treatment of heating the protruding portions of each of the conductive paths in contact with the electrode member in the presence of 2 volume % or more of formic acid.

2. The method for producing a bonded body according to claim 1, wherein the heating temperature in the bonding step is 150 to 250°C.

3. The method for producing a bonded body according to claim 1 or 2, wherein the heating time in the bonding step is 3 minutes or more.

4. The method for producing a joint body according to claim 1 or 2, wherein the arithmetic mean height of the protruding portion of each of the conductive paths is 100 nm to 5000 nm.

5. The method for producing a bonded body according to claim 1 or 2, wherein the concentration of formic acid in the bonding step is 15 volume % or less.

6. A method for producing a joint body according to claim 1 or 2, further comprising a temporary joining step of temporarily joining the anisotropic conductive joint member and the electrode member prior to the joining step.

7. The method for producing a joint body according to claim 1 or 2, wherein the conductive paths contain copper.

8. The method for producing a joint body according to claim 1 or 2, wherein the insulating substrate includes an anodized aluminum film.