Conductive bonding material, manufacturing method of conductive bonding material and bonding member

Abstract

To provide a conductive bonding material consisting of a metal powder molding, the conductive bonding material capable of being enlarged in area and approximated in a film state, and a manufacturing method thereof.SOLUTION: In a conductive bonding material consisting of a molding of a metal powder formed on a substrate and having a predetermined area, the metal powder is a powder consisting of a metal such as gold of which the purity is 99.9 mass% or more and the average grain diameter is 0.005 μm or more and 1.0 μm or less. The conductive bonding material is divided into a first region and a second region, which is a residual region, in a planar view, both a minimum dimension L1 of the first region and a minimum dimension L2 of the second region are 5 μm or more and a ratio of L1 and L2 is 0.25 or more and 4 or less. In the conductive bonding material, a clearance between the first region and the second region in a cross-sectional view is less than 1 μm and the conductive bonding material is in such a mode that it can be approximated in a film state. Examples of concrete shapes of the first region may include a lightning pattern, a waveform pattern, a concentric circle pattern, and a wave crest pattern.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a conductive bonding material that is applicable to bonding processes such as die bonding and flip chip mounting of semiconductor chips, and a manufacturing method thereof, and a bonding member including the conductive bonding material. [Background technology]

[0002] The applicant of the present application has proposed a method for manufacturing various devices in which a conductive bonding material made of a compact of metal powder is applied to die bonding, flip chip mounting, and the like (Patent Documents 1 to 4). This conductive bonding material is a sintered or dried body of metal powder made of a high-purity metal in a specified particle size range. In addition, a metal paste in which the above-mentioned metal powder is dispersed in a solvent is used as a precursor to form the conductive bonding material. In the bonding process using the applicant's conductive bonding material, the metal paste is applied to a substrate or base material such as a device, and then dried or fired to form a conductive bonding material, and then a member to be bonded such as a semiconductor element is placed on the conductive bonding material and heated under pressure to sinter the metal powder and complete the bonding.

[0003] The conductive bonding material made of the metal powder compact of the applicant of the present application has many advantages. That is, the conductive bonding material made of metal powder can be bonded at a temperature of 300°C or less. This allows bonding at low temperatures to be achieved with metal brazing materials (gold brazing, silver brazing, etc.) that have long been used as bonding materials. Such low-temperature bonding is useful for suppressing thermal damage to substrates, semiconductor elements, etc. Bonding with a metal powder compact is also effective from the viewpoint of ensuring the bonding strength of the bonded portion. In the bonding process, necking progresses and the metal particles themselves undergo plastic deformation inside the heated and pressurized metal powder sintered body, reducing the internal voids and densifying the material. The densified conductive bonding material can firmly bond semiconductor elements, etc., to the substrate. Furthermore, the metal paste, which is the precursor of the conductive bonding material, has good coating and printing properties when the solvent, etc. are appropriately configured, so that the bonding material can be easily formed into a desired shape.

[0004] Due to these advantages, the range of application of conductive bonding materials made of metal powder compacts is being considered to extend beyond various semiconductor elements made of Si-based semiconductors (single crystal Si, SiC, etc.) to bonding processes for power devices made of compound semiconductors such as Ga-based semiconductors (GaAs, GaN, GaP). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-324523 A [Patent Document 2] JP 2014-067917 A [Patent Document 3] Patent Publication No. 2021-125522 [Patent Document 4] Patent No. 5202714 specification Summary of the Invention [Problem to be solved by the invention]

[0006] Due to the expansion of the range of applications as described above, conductive joining materials made of metal powder compacts are required to have improved properties other than the low-temperature joinability that has been known up to now. For example, in joining power devices and the like that are expected in the future, the compound semiconductors mounted thereon are relatively fragile, so a reduction in the pressure applied during joining is required. The above-mentioned Patent Document 3 discloses a conductive joining material that can be joined even with low pressure by applying a metal powder compact with adjusted deformation resistance having predetermined parameters.

[0007] In addition, the bonding material needs to be made larger in area for bonding power devices and the like, whose chip size increases with increasing capacity. In this regard, it is inherently difficult to make conductive bonding materials with metal paste as a precursor large in area. In the manufacture of conductive bonding materials on a substrate, a resist is usually applied to the substrate, and then exposed and developed to open through holes in the resist, and a metal paste is applied and filled in the holes, and then dried and baked to form a conductive bonding material with a desired pattern. At this time, since the metal paste contains a solvent in addition to the metal powder, the through hole is filled with an excess of metal paste relative to its depth, taking into account the volume reduction due to the evaporation of the solvent after drying and baking. The metal powder that protrudes from the through hole is then scraped off and removed with a squeegee or the like, but the surface of the conductive bonding material may be gouged out due to the action of shear stress during scraping, resulting in a loss of flatness. The decrease in flatness becomes more pronounced as the scraping distance increases, making it difficult to make the conductive bonding material large in area.

[0008] The above-mentioned Patent Document 3 also proposes a conductive bonding material that takes into consideration both a large area and flatness. In this prior document, multiple conductive bonding materials are set and are arranged close to each other with an interval of 1 μm. In this way, a pseudo-integral film-like bonding material composed of multiple conductive bonding materials can be obtained.

[0009] However, even if the conductive bonding material of Patent Document 3 is approximated to a film, there are still gaps. And even if the gaps are minute, about 1 μm, they can affect the conductivity and heat dissipation at the junctions of the device.

[0010] The present invention has been made under the above-mentioned background. The purpose of the present invention is to provide a conductive bonding material made of a molded body of a specified metal powder by the applicant of the present application, which can increase the area in which the metal powder molded body is formed and minimize the gaps in the area, thereby providing a conductive bonding material that is closer to a film-like form than ever before, and a method for manufacturing the same. [Means for solving the problem]

[0011] The present inventors have considered that in order to increase the area of ​​a conductive bonding material made of a metal powder compact, it is preferable to carry out the process of applying a metal paste and forming a metal powder compact in two stages. If it is unavoidable to form a gap of 1 μm or more when manufacturing a compact of a metal powder using a metal paste as a precursor, it is possible to manufacture a compact with a gap intentionally in the first stage, and fill the gap with a metal paste in the second stage and dry it to form an integrated compact.

[0012] However, according to the study by the inventors, even in such a two-stage manufacturing process, depending on the width of the gap between the molded bodies formed in the first stage, it has been confirmed that the metal powder of the metal paste cannot be sufficiently filled in the gap in the second stage. For example, referring to the above Patent Document 3, the inventors have confirmed that when a conductive bonding material is formed while leaving a gap of 1 μm or more (4 μm) and a metal paste is further applied to fill the gap, the metal powder stops at the top of the gap (near the opening) and cannot be filled to the bottom of the gap (near the substrate). Although the size (particle size) of the metal powder in the metal paste itself is smaller than the gap, it does not reach the bottom of the gap due to the influence of the viscosity and surface tension of the metal paste.

[0013] Therefore, the inventors conducted research to find suitable shape and size conditions based on the two-stage process of forming a metal powder compact, and as a result, arrived at the conductive bonding material of the present invention.

[0014] That is, the present invention provides a conductive bonding material consisting of a metal powder compact having a predetermined area formed on a substrate, wherein the metal powder constituting the compact is a powder consisting of one or more metals selected from the group consisting of gold, silver, platinum, and palladium with a purity of 99.9% by mass or more and an average particle size of 0.005 μm or more and 1.0 μm or less, wherein the conductive bonding material is divided into a first region and a second region which is the remaining region, in a planar view, wherein both the minimum dimension L1 of the first region and the minimum dimension L2 of the second region are 5 μm or more, and the ratio L1 / L2 of L1 to L2 is 0.25 or more and 4 or less, and further wherein the conductive bonding material has a gap between the first region and the second region in a cross-sectional view of less than 1 μm.

[0015] Here, the minimum dimensions L1, L2 of the first and second regions are preferably 140 μm or less.

[0016] The first region may have a shape in which two or more unit squares having a side length equal to the minimum dimension L1 are successively formed in a regular pattern.Furthermore, the first region may have a shape in which a curve having a line width equal to the minimum dimension L1 is successively formed in a regular pattern.

[0017] The bonding member according to the present invention includes a base material and at least one of the conductive bonding materials described above.

[0018] The conductive bonding material according to the present invention is formed by carrying out two steps of applying a predetermined metal paste and drying and sintering it. That is, the method for producing a conductive bonding material according to the present invention is a method for producing a conductive bonding material using a metal paste containing one or more metals selected from the group consisting of gold, silver, platinum, and palladium at 99.9 mass % or more and a metal powder having an average particle size of 0.005 μm to 1.0 μm, and includes a step of covering a substrate surface with a resist, a first step of forming a first through hole in a region corresponding to a first region of the resist, filling the first through hole with the metal paste, and then forming a compact of the metal powder contained in the metal paste, a second step of forming a second through hole in a region corresponding to a second region of the resist after the first step, filling the second through hole with the metal paste, and then forming a compact of the metal powder contained in the metal paste, and a step of removing the remaining resist. Effect of the Invention

[0019] As described above, the conductive bonding material according to the present invention is divided and segmented into a first region and a second region with appropriate dimensions. This allows the area of ​​the metal powder molding to be increased while narrowing the gap more than ever before. The conductive bonding material according to the present invention can exhibit more effective heat dissipation and conductivity than ever before. Furthermore, the present invention makes it easy to achieve both an increase in the area of ​​a conductive bonding material and ensuring flatness, which was previously difficult. [Brief description of the drawings]

[0020] [Figure 1] 1A to 1C are diagrams illustrating the planar shape, cross-sectional structure, and minimum dimensions of one embodiment of a conductive bonding material according to the present invention. [Diagram 2] FIG. 2 is a diagram showing a specific example of a planar shape of a conductive bonding material of the present invention that is formed of a unit square. [Diagram 3] FIG. 2 is a diagram showing a specific example of a conductive bonding material according to the present invention having a planar shape formed of a curve. [Figure 4] 1 is a diagram showing an example of the overall shape of a conductive bonding material of the present invention; [Figure 5a]FIG. 2 is a diagram (first region) illustrating a process for forming a conductive bonding material of the present invention. [Figure 5b] FIG. 3 is a diagram (second region) illustrating the process for forming the conductive bonding material of the present invention. [Figure 6] 1A to 1C are diagrams illustrating a mode of use of a bonding member to which the conductive bonding material of the present invention is applied. [Figure 7] Photographs of the manufacturing process of the conductive bonding material of the embodiment. [Figure 8] Photographs of the appearance and cross section of the conductive bonding material produced in the examples. [Figure 9] Photographs of the appearance and cross section of the conductive bonding material produced in the reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] (A) First and second regions of conductive bonding material The configuration and embodiment of the present invention will be described below with reference to specific examples. Figure 1 shows an example of a specific embodiment of the conductive bonding material according to the present invention. As shown in Figure 1(a), this conductive bonding material has a rectangular shape as a whole in a plan view, and is formed with a first region in which a plurality of zigzag patterns are aligned. The remaining regions, that is, the gaps between the zigzag patterns, become the second regions. In this conductive bonding material, the first region and the second region are both made of a compact of metal powder of the same metal type and particle size.

[0022] FIG. 1(b) is a diagram showing the cross-sectional structure of this conductive bonding material. There is a fine gap between the metal powder compact in the first region and the metal powder compact in the second region, and this gap divides the first region and the second region. The cause of this gap is due to the method of forming the metal powder compact, which is performed in two stages, which will be described later. However, even though it is called a gap, the distance between the first region and the second region in the present invention is less than 1 μm. Therefore, it is narrower than the gap (1 μm or more) in the conventional technology (Patent Document 3), and can act as a continuous film-like conductive bonding material more than before. The gap between the first region and the second region in the present invention is preferably 0.8 μm or less, more preferably 0.5 μm or less.

[0023] The minimum dimensions L1 and L2 of the first and second regions are the minimum dimensions among the dimensions measured at any position of the metal powder compact in each region. For example, as shown in Fig. 1(c), in the conductive bonding material of this embodiment, the first region is formed with a zigzag pattern of straight lines of the same width, and the minimum dimension L1 of the first region is the line width. On the other hand, the minimum dimension L2 of the second region in Fig. 1 corresponds to the minimum value of the interval between the aligned zigzag patterns.

[0024] In the present invention, both the minimum dimension L1 of the first region and the minimum dimension L2 of the second region must be 5 μm or more. In the process of forming a metal powder compact using a metal paste, the minimum dimensions L1 and L2 are the minimum width of the hole into which the metal powder is filled. According to the inventors' study, if the width of the hole is less than 5 μm, it becomes difficult to fill the bottom of the hole with the metal powder. As a result, the contact area of ​​the conductive bonding material with the base material decreases, which reduces heat dissipation and conductivity.

[0025] It is preferable that the minimum dimensions L1 and L2 are both 10 μm or more. Moreover, the larger the minimum dimensions L1 and L2, the easier it is to fill the metal powder at each stage. However, if the minimum dimensions are excessively large, there is a possibility that the surface of the metal powder will be gouged out significantly when the excess metal powder is scraped off, resulting in loss of flatness. From this viewpoint, it is preferable that the minimum dimensions L1 and L2 are 140 μm or less, and more preferably 80 μm or less.

[0026] In addition, taking into consideration the relationship between the first region and the remaining second region, the ratio L1 / L2 of the minimum dimension L1 of the first region and the minimum dimension L2 of the second region is set to 0.25 to 4. The smaller this difference in dimensions is, the more patterns of the same width are formed, and the more reliable the filling of the metal powder tends to be. L1 / L2 is preferably 0.5 to 2, and more preferably 0.8 to 1.25.

[0027] In the conductive bonding material according to the present invention, the planar shapes of the divided first and second regions can be determined on the premise that their minimum dimensions L1 and L2 satisfy the above-mentioned relationship. Therefore, the first region may be a shape of an array of simple rectangles, and the remainder may be the second region.

[0028] However, in order to stably form the metal powder compacts in both regions, it is preferable that the planar shape of the first region is a pattern having a bent portion. In the conductive bonding material of the present invention, which is manufactured through the stepwise processes of the first and second processes described below, the metal powder compact in the first region is already formed when the metal powder compact in the second region is formed. In forming the metal powder compact, a scraping process is required to remove the excess metal powder, and at that time, the metal powder compact in the first region may be subjected to a shear force and may be deformed or damaged. Therefore, by forming the first region into a bent pattern, the shear strength of the metal powder compact in the first region is ensured in the vertical, horizontal and diagonal directions. This makes it possible to stably form a metal powder compact with little risk of deformation, etc.

[0029] Specifically, the first region is formed in a regular pattern of two or more unit squares with the minimum dimension L1 as the side length. Two or more unit squares are formed in a regular pattern of unit squares connected vertically, horizontally, or diagonally. The first region may also be formed in a regular pattern of continuous curves with the minimum dimension L1 as the line width. Continuous curves are not limited to cases where the ends of curves are connected to each other, but also include cases where one part of a curve is connected to another part of a curve. Continuous curves also include circles and spiral patterns.

[0030] More specific examples of the planar shape of the conductive bonding material consisting of the first region and the remaining second region include the pattern-like shapes shown in Figures 2 and 3. The specific example shown in Figure 2 is a pattern of unit squares with a side length of L1, such as a checkered pattern and a straight wave pattern. The snake pattern in Figure 1 also falls into this category. The snake pattern and wave pattern in Figure 2 are patterns formed by successive unit squares with a minimum dimension of L1 and lines with a line width of L1. The checkered pattern in Figure 2 can also be said to be a pattern of unit squares with a minimum dimension of L1 continuing in a diagonal direction. On the other hand, Figure 3 shows specific examples of the first region mainly consisting of curves, such as a concentric circle pattern and a blue sea wave pattern.

[0031] The shape and dimensions of the first and second regions combined, i.e., the overall shape and dimensions of the conductive bonding material of the present invention, are not particularly limited. As shown in Fig. 4, the overall shape of the conductive bonding material may be rectangular or circular. The dimensions are also set arbitrarily, taking into consideration the members to be bonded, such as elements to be bonded.

[0032] (B) Structure of metal powder compact The first and second regions of the conductive bonding material according to the present invention are both metal powders made of one or more metals selected from the group consisting of gold (Au), silver (Ag), platinum (Pt) and palladium (Pd), having a purity of 99.9% by mass or more and an average particle size of 0.005 μm to 1.0 μm.

[0033] The purity of the metal constituting the metal powder is set to 99.9% by mass or more in order to impart the metal powder with the plastic deformability required for a joining material. The conductive joining material of the present invention is densified from the state of a compact to a state close to a bulk metal to form a joining part. High purification of the metal powder is an essential condition for causing plastic deformation by pressure in the joining process. When the purity of the metal powder is low, less than 99.9% by mass, the hardness of the metal powder increases, making it difficult for plastic deformation of the metal particles themselves to occur in the joining process, and preventing compressive deformation of the compact. In particular, it becomes difficult to form a suitable joining part in a situation where the pressure applied during joining is low.

[0034] The reason why the average particle size of the metal powder is set to 1.0 μm or less is that metal powder with a particle size exceeding 1.0 μm tends to have too large gaps between particles when used as a conductive bonding material. If the voids in the conductive bonding material are large, densification is hindered in the bonding process, making it difficult to obtain a suitable bonding strength. On the other hand, the reason why the lower limit of the average particle size of the metal powder is set to 0.005 μm is that if the particle size is less than this, the powder is likely to aggregate when made into a paste. And the reason why the constituent metal is set to any one of gold, platinum, silver, and palladium is that these metals have good conductivity and good deformability when made into a pure metal. In addition, the present invention does not prevent the use of a mixture of multiple powders with different average particle sizes as long as the average particle size is in the range of 0.005 μm to 1.0 μm.

[0035] The metal powder compact is not limited to a sintered metal powder, but includes an unsintered state (hereinafter referred to as a dried body) in which metal powder is layered and dried. A sintered metal powder is a compact formed by strong bonding between metal powders due to necking or thermal diffusion. A dried metal powder is a compact formed by relatively weak bonding between metal powders, in which the metal powders are in contact with each other but no necking or thermal diffusion occurs. Therefore, the hardness of each metal powder in the dried body is approximately the same before and after it is made into a compact. Note that, even if the bonding is weak, it is not so weak that the compact collapses when used in a joining process or the like. In the present invention, whether the metal powder compact is formed as a sintered body or a dried body is determined in consideration of the pressure required in the subsequent joining process. For example, when bonding at low pressure is required, the application of a dried body is preferable. This is because a compact made of metal powder that is formed by drying and has little thermal change can be densified at low pressure.

[0036] The metal powder compacts in the first and second regions may both be sintered or dried, or one of them may be a sintered body and the other a dried body.

[0037] The metal powder compact constituting the conductive bonding material of the present invention preferably has a relative density of 50% or more and 95% or less with respect to the bulk material. The relative density is the value expressed as a percentage (%) obtained by dividing the true density of the metal by the measured density of the conductive bonding material (relative density (%) = [(measured density of the conductive bonding material) / (true density of the metal)] × 100). The relative density of a sintered body tends to be high, while the relative density of a dried body tends to be lower than that of a sintered body.

[0038] In addition, in the conductive bonding material of the present invention, the metal powder compact is divided into a first region and a second region, and the minimum dimensions L1 and L2 of the regions are specified, so that the conductive bonding material has a large area and excellent flatness. Regarding flatness, the ratio of the maximum amount of hollowing to the average thickness of the metal powder compact is 50% or less. This standard applies to both the first and second regions. The average thickness of the compact is the average value when the thickness is observed and measured at multiple points on an arbitrary cross section. The maximum amount of hollowing is the deviation from the average thickness at the portion with the smallest thickness. The thickness of the conductive bonding material of the present invention is not particularly limited.

[0039] The conductive bonding material made of the above-described molded body of metal powder undergoes thermal diffusion between the metal particles when heated after bonding, and changes into a dense sintered body, which can firmly bond the semiconductor chip and the substrate. The conductive bonding material according to the present invention is a bonding member that has an appropriate hardness while suppressing deformation resistance when pressure is applied. Positioning of the semiconductor chip, etc. during bonding can also be performed accurately and with high precision.

[0040] (C) A joining member having a conductive joining material The conductive bonding material according to the present invention is formed on the surface of a suitable substrate and used as a bonding member. The substrate is a member for supporting the conductive bonding material in order to efficiently handle the conductive bonding material. The substrate may be a substrate for a semiconductor device or the like. In this case, the conductive bonding material according to the present invention is formed on the substrate, and then an element or the like is bonded to the substrate to form a device. The conductive bonding material according to the present invention can also be applied to a transfer substrate (Patent Document 4). In this case, the conductive bonding material is once formed on the transfer substrate, and then transferred to the substrate or the like of the device to function as a bonding material for the element or the like.

[0041] Regarding the material of the substrate, any material may be used as long as it can hold the conductive bonding material. For example, materials such as glass, quartz, silicon, or ceramics are exemplified. The shape and dimensions of the substrate are not particularly limited, and a rectangular, circular, polygonal, or other flat plate may be used. The substrate may be only the above-mentioned glass or silicon, or a thin film made of a metal or an oxide of these metals may be formed on the surface of the substrate. This thin film becomes a base film that improves the adhesion between the substrate and the conductive bonding material. The base film is made of a metal or a metal oxide such as Ti, Cr, Cu, or Ni, and can be made of at least one thin film layer. The thickness of the base film is preferably 5 nm to 300 nm.

[0042] The bonding member of the present invention may have only one conductive bonding material formed on a base material, or may have a plurality of conductive bonding materials formed on the base material.

[0043] The bonding member according to the present invention may have an intermediate film made of a metal or an oxide of the metal between the conductive bonding material and the substrate. The intermediate film, like the undercoat film described above, can adjust the adhesion between the conductive bonding material and the substrate, thereby ensuring the ease of handling of the conductive bonding material and the bonding quality. That is, the intermediate film can prevent the conductive bonding material from falling off when the bonding member is handled, and can suppress the conductive bonding material from remaining on the substrate when the conductive bonding material is peeled off from the substrate in the bonding process.

[0044] The material of the intermediate film is preferably one or more metals selected from the group consisting of Au, Ag, Pt, and Pd, and more preferably the same metal as the conductive bonding material. The reason for selecting these materials is to increase the affinity between the intermediate film and the metal constituting the conductive bonding material while reducing the resistance. Pure metals and alloys of the above metals can be used as long as they do not interfere with this purpose. The intermediate film can also be composed of at least one thin film. In addition, an intermediate film may be formed between the substrate and the conductive bonding material together with the above-mentioned undercoat film, or only an intermediate film may be formed.

[0045] The intermediate film may be a single layer or multiple layers. When multiple intermediate films are formed, the intermediate films may be made of the same metal or different metals. However, the intermediate film in contact with the conductive bonding material is preferably made of the same metal as the conductive bonding material.

[0046] The thickness of the intermediate film is preferably 5 nm or more and 300 nm or less. If it is less than 5 nm, the above effect is weak, and if it exceeds 300 nm, there is no difference in the effect and it only increases the material cost. When forming a plurality of intermediate films, it is preferable that the total thickness is in the above range.

[0047] The intermediate film is provided at least between the conductive bonding material and the substrate. The intermediate film may be present only on the bottom surface of the conductive bonding material, or may be formed on the entire surface of the substrate. The intermediate film may also be present in the gap between adjacent conductive bonding materials. Furthermore, the intermediate film may be present at least on the bottom surface of the conductive bonding material, but may also be formed on the side surface of the conductive bonding material.

[0048] (D) Method for producing conductive bonding material Next, an embodiment of the method for producing a conductive bonding material according to the present invention will be described. The conductive bonding material according to the present invention is basically formed by applying a metal paste containing a predetermined metal powder onto a substrate, and drying or sintering the metal paste to form a molded body. As described above, in the present invention, in order to form a molded body of metal powder having a narrowed gap, the molded body is divided into first and second regions, and the process of forming the molded body of the metal powder is carried out twice in stages for each region as the first and second processes. In the following description of the method for producing a conductive bonding material according to the present invention, the preparatory process for the substrate (I) resist coating process and through hole formation process, the common process for the first and second processes (II) filling the through holes by applying a metal paste, and (III) forming a molded body from the metal powder will be described, and then the overall process will be described.

[0049] (I) Resist coating process and through-hole formation process The metal powder compacts in the first and second regions of the conductive bonding material of the present invention are assumed to be formed in a pattern as shown in FIG. 2 and the like. Since they have more complex shapes than compacts with simple shapes such as rectangles, it is preferable to form them by patterning using a resist (protective film). Regarding the resist, a photoresist used in normal device manufacturing is preferable, but there is no restriction on the photosensitive wavelength or the type such as positive type or negative type. There is no restriction on the method of applying the resist, and the same method as in the past can be applied. Then, after forming a coating film with the resist, a through hole patterned according to the shape of the first region is formed. A through hole is a hole that penetrates the resist film and reaches the bottom surface (substrate surface) from the resist surface. The through hole forming process involves exposure and etching of the resist, and these methods are also generally applied.

[0050] (II) Filling the through holes by applying metal paste After the above preparation process of coating with resist and forming through holes, a metal paste is applied to the substrate. The metal paste is constituted as a slurry in which one or more metal powders selected from the group consisting of gold powder, silver powder, platinum powder, and palladium powder, each having a purity of 99.9 mass% or more and an average particle size of 0.005 μm to 1.0 μm, are dispersed in an organic solvent. The organic solvent preferably has a boiling point of 250° C. or less. The reason for setting the boiling point of the organic solvent to 250° C. or less is that drying requires a high temperature and a long time, which causes necking to form between the metal particles of the molded body, inhibiting the movement of the metal particles due to the pressure applied during bonding, thereby reducing the bonding strength.

[0051] As organic solvents that can be used in the present invention, branched saturated aliphatic dihydric alcohols, monoterpene alcohols, halocarbons, etc. can be applied. More specifically, as branched saturated aliphatic dihydric alcohols, propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, and derivatives thereof such as 2,4-diethyl-1,5-pentanediol can be used. As the monoterpene alcohol, citronellol, geraniol, nerol, menthol, terpineol (α, β), carveol, thuyl alcohol, pinocampheol, β-fenchyl alcohol, dimethyloctanol, hydroxycitronellol, 2,4-diethyl-1,5-pentanediol, trimethylpentanediol monoisobutyrate, and derivatives thereof can be used. As the chain saturated hydrocarbon, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, and derivatives thereof can be used. Compounds obtained by condensation reaction of monovalent carboxylic acid and polyhydric alcohol are also effective, such as triethylene glycol di-2-ethylhexanoate and triethylene glycol di-2-ethylbutanoate. As the organic solvent of halocarbons, tetrachloroethylene, tetrabromoethylene, tetraiodoethylene, and trichloromethane can be used. In addition, since the boiling point of an organic solvent tends to depend on its carbon number, it is preferable that the applied solvent has 5 to 20 carbon atoms. From this viewpoint, aromatic hydrocarbons may be used, and for example, terpineol, menthanol, and alkylbenzenes used as solvents for thick film pastes are functionally acceptable. As for the organic solvent, one type of organic solvent may be used, but a mixture of two or more organic solvents with different boiling points may also be used.By using organic solvents having low and high boiling points, the organic solvent with the low boiling point can be removed by evaporation during the process of adjusting the content of metal particles, making the adjustment easier.

[0052] The method of applying the metal paste to the substrate is not particularly limited, and various methods can be used depending on the size of the substrate, such as spin coating, screen printing, inkjet, and blade coating. The metal paste can be applied at room temperature and pressure. However, it may be applied in a reduced pressure atmosphere. In particular, when applying the metal paste to a substrate on which a pattern has been formed using a resist, it is preferable to apply the metal paste in a reduced pressure atmosphere in order to sufficiently fill the pores with the metal paste.

[0053] (III) Metal powder compact forming process The metal powder filled in the through holes by applying the metal paste is dried or sintered to become a metal powder compact. Whether to dry or sinter in this process is determined based on the required strength of the compact and the required pressure when used as a joining material.

[0054] When the metal powder compact is dried, the drying process heats the metal paste without applying pressure to form a compact while volatilizing and removing the organic solvent in the paste. As the processing conditions for the drying process, the drying temperature is less than 100°C. If the process is performed at a high temperature exceeding this temperature, the metal powder will be sintered even without applying pressure, and a part or the whole of the compact will become a sintered body. The drying temperature is preferably 65°C or less, and more preferably 60°C or less. The lower limit of the drying temperature is sufficient as long as it is a temperature at which the organic solvent can be volatilized or higher. However, in order to form a dried body that shows suitable deformation when pressure is applied during bonding, it is preferable to set the temperature at 20°C or higher. The atmosphere for the drying process may be under atmospheric pressure, but may also be a vacuum atmosphere of 0.01 Pa to 40 kPa. Vacuum drying contributes to lowering the drying temperature, and in that case, the temperature is preferably 10°C to 30°C. The drying time under these drying process conditions is preferably 0.1 hours to 1 hour. These drying processes are carried out under relatively mild thermal conditions, and generally allow the solvent to be removed without destroying the arrangement of the metal powder in the metal paste.

[0055] When the compact of the metal powder is made into a sintered body, the sintering conditions are preferably a heating temperature of 80°C or more and 300°C or less. At temperatures below 80°C, it is difficult to obtain a sintered state. Furthermore, if sintering is performed at a temperature exceeding 300°C, the sintering proceeds excessively, causing necking between the metal powders to proceed and resulting in strong bonding, making it difficult to form a dense joint when subjected to a joining process. Furthermore, the present invention aims to achieve joining at 300°C or less from the viewpoint of protecting the joining members. The heating time during sintering is preferably 5 minutes or more and 120 minutes or less. Furthermore, when forming a sintered body, the above-mentioned drying treatment may be performed as a preliminary step before sintering.

[0056] The above drying or sintering process can produce the conductive bonding material and bonding member according to the present invention. As described above, the bonding member including the conductive bonding material of the present invention may include at least one intermediate film between the conductive bonding material and the substrate. In this case, the intermediate film is preferably formed after the application of the resist and the formation of the through holes and before the application of the metal paste. This allows the intermediate film to be selectively formed between the conductive bonding material and the substrate. In addition, by forming the intermediate film after the application of the resist and covering the resist with a metal, it is possible to prevent the solvent of the metal paste from directly contacting the resist, and to reduce damage to the resist caused by the solvent. In addition, for the formation of the intermediate film, a normal thin film forming process such as sputtering, vacuum deposition, and chemical vapor deposition can be applied.

[0057] A specific embodiment of the method for producing a conductive bonding material of the present invention, which has the above-mentioned basic steps (I) to (III), will be described with reference to Figures 5a and 5b. This specific embodiment is a process including forming an intermediate film between the conductive bonding material and the substrate. Figure 5a illustrates the first step of forming a compact of metal powder in the first region, and Figure 5b illustrates the second step of forming a compact of metal powder in the second region, thereby completing the production of the conductive bonding material according to the present invention.

[0058] Referring to FIG. 5a, first, a substrate 1 is prepared and a resist 2 is applied to the substrate 1 (FIG. 5a(i)). A Ti film or the like may be formed in advance as an undercoat film on the substrate 1. Then, a photomask 3 having a pattern that will become the first region is used to expose and etch the resist in the area that will become the first region, thereby forming a through hole 4 (FIG. 5a(ii)). Next, an intermediate film 5 made of gold or the like is formed on the bottom surface of the through hole and on the surface of the resist (FIG. 5a(iii)).

[0059] Next, a metal paste 6 is applied onto the resist 2 of the substrate 1, and the through holes 4 in the first region are filled with metal powder (FIG. 5a(iv)). A drying process is then performed to form a metal powder compact (FIG. 5a(v)), and excess metal powder is removed with a squeegee or the like to form a metal powder compact corresponding to the first region (FIG. 5a(vi)).

[0060] After the first region is formed in the above-mentioned first step, a metal powder compact is formed in the second region in the second step. In the second step, it is necessary to remove the resist in the portion corresponding to the second region by exposing and etching it. Here, the intermediate film remaining on the entire resist surface is once removed by etching, and then a metal film 8 is formed on the resist surface other than the first and second regions by masking 3 (FIG. 5b(i)). Then, exposure and etching are performed to form a through hole 9 that will become the second region (FIG. 5b(ii)), and further, an intermediate film 5 is formed on the bottom surface of the through hole (FIG. 5b(iii)). In addition to this embodiment, after the intermediate film is removed from the entire resist surface by etching, only the resist in the second region may be exposed and etched using a photomask.

[0061] After forming the through holes corresponding to the second region, metal paste 6 is applied as in the first process to fill the through holes with metal powder, and a drying process is performed to form a metal powder compact for the second region (Figure 5b (iv)). Thereafter, excess metal powder is removed (Figure 5b (v)). Finally, the resist is removed to form a metal powder compact 10 for the second region, and the conductive bonding material 11 of the present invention is produced (Figure 5b (vi)).

[0062] (E) Aspects of the bonding method using a conductive bonding material The conductive bonding material made of the metal powder compact according to the present invention is suitably used for bonding a substrate of a semiconductor device, etc., and a bonded material such as an element or chip, etc. Three specific examples of bonding methods to which this conductive bonding material is applied are described with reference to Figs. 6(a), (b), and (c).

[0063] 6(a), a substrate such as a device is used as the base material of the bonding member of the present invention, and a bonded member is bonded to the bonding member having a conductive bonding material formed on the substrate. In the bonding process, the bonded member is placed on the conductive bonding material, and then pressure and heat are applied to sinter the metal powder of the conductive bonding material to form a densified bonded portion.

[0064] The pressure in the bonding process is set in consideration of the pressure that the semiconductor chips to be bonded can withstand. Semiconductor chips that have relatively high strength, such as Si-based semiconductor chips, can be bonded with a pressure of 30 MPa or less. On the other hand, for bonding compound semiconductor chips, which tend to have low strength and be brittle, the pressure is preferably 10 MPa or less, and 5 MPa or less is particularly preferable. The lower limit of the pressure is preferably 1 MPa or more, regardless of the type of semiconductor chip. If the pressure is less than 1 MPa, the deformation of the metal powder is difficult to progress, and the bonded portion cannot be densified.

[0065] The main purpose of the heating in the bonding process is to enhance the plastic deformability of the metal powder and assist in densification by pressure application. This heating is also expected to promote sintering of the metal powder in part or the whole of the conductive bonding material. The heating temperature is preferably 80°C or higher and 300°C or lower. If the temperature is lower than 80°C, the plastic deformability of the metal particles cannot be enhanced and strong bonding cannot be obtained. If the temperature exceeds 300°C, there is a concern that the semiconductor chip and the substrate may be damaged.

[0066] The heating temperature is set in consideration of the heat resistance of the semiconductor chip and the substrate. For example, in the case of a resin-based organic substrate, if the glass transition temperature (Tg) is exceeded, physical properties such as mechanical strength and dielectric constant may change significantly. The heating temperature for such a substrate with low heat resistance is preferably 230°C or less, and more preferably 200°C or less. The present invention can contribute to reducing the heating temperature as well as reducing the pressure in the bonding process. The conductive bonding material is heated from either or both of the semiconductor chip side and the substrate side. It is preferable that the heating from either side is within the above range.

[0067] The heating time (pressurizing time) in the bonding process affects the bonding strength between the conductive bonding material and the bonded member and the density of the conductive bonding material, with the bonding strength and density increasing with increasing time. Even with a relatively short heating time of 0.5 to 120 seconds, it is possible to compress and deform the conductive bonding material and bond the semiconductor chip and substrate. Furthermore, a stronger bond can be achieved by setting the heating time to 10 to 120 minutes.

[0068] After the above-mentioned bonding step, the conductive bonding material may be heated. By carrying out such post-heat treatment, the metal powder is sintered (post-sintered) and the voids inside the conductive bonding material are reduced or decreased, so that the material can be further densified. For example, the heating time in the bonding step may be set to 0.5 seconds or more and 120 seconds or less, and then the material may be bonded and then heated for post-sintering.

[0069] The heating temperature for post-sintering the conductive bonding material is preferably 100°C or higher and 300°C or lower. If the temperature is lower than 100°C, the desired progress of sintering and densification cannot be expected. If the temperature exceeds 300°C, sintering will proceed excessively, and only the joint will become too hard. This heating temperature is also set in consideration of the heat resistance temperature of the semiconductor chip and the substrate. Therefore, the heating temperature for substrates with low heat resistance, such as resin-based organic substrates, is preferably 230°C or lower, and more preferably 200°C or lower.

[0070] The heating time for post-sintering is preferably 10 minutes or more and 120 minutes or less. If it is less than 10 minutes, the desired sintering cannot be completed, and if it is heated for more than 120 minutes, further densification cannot be expected. The heat treatment for sintering may be performed without pressure, but may also be performed with pressure. If pressure is applied, it is preferable to apply pressure at 10 MPa or less.

[0071] In the embodiment of the bonding step shown in Fig. 6(b), the base material of the bonding member functions as a support material for forming and supporting the conductive bonding material, and the conductive bonding material is bonded to a substrate of a device other than the base material together with the bonded member. In this embodiment, the conductive bonding material is mounted (fixed) to the bonded member such as an element by applying pressure and heat, and then the bonded member and the conductive bonding material are picked up from the base material. Then, the picked-up conductive bonding material and bonded member are placed on the substrate of the device or the like and bonded by applying pressure and heat.

[0072] The fixing conditions when mounting the conductive bonding material on the bonded member are preferably a pressure of 1 MPa or more and 5 MPa or less, and a heating temperature of 100° C. or more and 200° C. or less. After mounting the bonded member, the semiconductor chip is picked up from the substrate to obtain a semiconductor chip with the conductive bonding material fixed thereto.

[0073] The bonded members to which the conductive bonding material is fixed are then placed on a substrate such as a device, and pressure and heat are applied to bond the bonded members to the substrate. The pressure, heat, and pressure and heating time in this bonding process are preferably set to a pressure of 1 MPa to 30 MPa and a heating temperature of 80°C to 300°C. Details of the preferred conditions are the same as those for the bonding process of the embodiment shown in Fig. 6(a) above.

[0074] In this embodiment of the bonding step, post-sintering may be performed in which the conductive bonding material is heated under the same conditions as in the embodiment of FIG. 6(a) described above.

[0075] In addition, there is no limitation on the material, shape, and size of the substrate of the device to which the member to be bonded is bonded in this manner. It can be used for resin-based organic substrates, and is also useful for substrates (wafers) made of Si-based materials and ceramic substrates.

[0076] In the embodiment of the bonding step in FIG. 6(c), the conductive bonding material on the base material is transferred to a substrate such as a device, and then a bonded member such as an element is bonded to the substrate. This embodiment is the same as the embodiment in FIG. 6(b) in that the base material of the bonding member is used as a support for the conductive bonding material. In this embodiment, a substrate such as a device is placed on the bonding material on which the conductive bonding material has been formed, and the conductive bonding material is transferred to the substrate by heating, and the substrate is then picked up. Then, a bonded member such as an element is placed on the conductive bonding material transferred to the substrate, and bonded by applying pressure and heat.

[0077] The conductive bonding material of the bonding member is preferably heated when transferred to the substrate so that the conductive bonding material to be transferred reaches 100 to 200°C. This is to facilitate the transfer of the conductive bonding material from the substrate of the bonding member to the substrate. The conductive bonding material may be heated together with the substrate of the bonding member. In addition, it is preferable to apply pressure with a stress equal to or less than the yield strength of the conductive bonding material while heating.

[0078] The pressure, heat, and pressurizing / heating time in the bonding process for bonding the substrate to which the conductive bonding material has been transferred to the substrate are preferably set to a pressure of 1 MPa to 30 MPa and a heating temperature of 80°C to 300°C. The details of the suitable conditions are the same as those of the bonding process of the embodiment of Fig. 6(a) described above. Heating for post-sintering may also be performed in this bonding process.

[0079] In the specific embodiment of the bonding process of Fig. 6(a) to (c) described above, it is preferable to form a metal film on the bonding surface between the substrate of a device or the like and the bonded member of an element or the like. This is to improve the adhesion between the substrate and the bonded member. The metal film can be formed on either or both of the bonding surface of the bonded member and the substrate. The metal film is preferably made of one or more metals selected from Au, Ag, Pt, and Pd, and may have a single-layer structure or a multi-layer structure. In addition, the surface (layer) in contact with the conductive bonding material is more preferably made of the same metal as the conductive bonding material. EXAMPLES

[0080] A specific embodiment of the present invention will be described. In this embodiment, a metal paste (gold paste) using gold powder as the metal powder was prepared, and a conductive bonding material and a bonding member were manufactured. Then, a bonding test of a semiconductor chip using this bonding member was carried out.

[0081] [Preparation of gold paste] A metal paste (gold paste) was prepared by mixing gold powder (average particle size: 0.3 μm) with a purity of 99.9% by mass produced by the wet reduction method with tetrachloroethylene (product name: Asahi Park Roll) as an organic solvent. The gold powder content of the gold paste was 90% by mass. The particle size of the gold powder was measured using a scanning electron microscope (SEM). The observed image (30,000x) was analyzed, and the particle sizes of 100 gold particles were measured to calculate the average particle size.

[0082] [Formation of the first region (first step)] A conductive bonding material consisting of the first and second regions was manufactured according to the same process as shown in Fig. 5a and b above. A silicon wafer (diameter 150 mmφ, plate thickness 0.6 mm) was used as the substrate. A Ti film (thickness 50 nm) was formed as an undercoat film on the entire surface of the substrate. First, a resist was applied to a thickness of 10 μm on the entire surface of the substrate, and then a Cr metal photomask having a zigzag pattern similar to that of Fig. 1 was placed over the substrate and exposed to light. The resist in the portion that would become the first region was removed with an etching solution to form a through hole. Then, a gold film with a thickness of 200 nm was formed as a metal film by sputtering.

[0083] Next, the gold paste prepared above was dropped onto the substrate and spread with a spatula using a blade coating method to fill the through-holes with gold powder. After applying the gold paste, the gold powder in the through-holes was vacuum dried to form a compact. The vacuum drying conditions were an atmosphere of 10 -1 The metal powder compact was then heated at room temperature for 1 hour at 20 Pa. The excess gold powder was then scraped off with a squeegee to form the first region of the metal powder compact. Figure 7(a) is a photograph of the first region of the metal powder compact at this stage taken from above. In this figure, the dark colored parts are the metal powder compact and the light colored parts are the resist.

[0084] [Formation of the second region (second process)] After the gold film on the resist surface was removed by etching, the first and second regions were masked and a gold film (200 nm) was formed again, and exposure and etching were performed under the same conditions as above to remove the resist in the second region and form a through hole that would become the second region. A gold film (200 nm) was sputtered onto the bottom of this through hole. Figure 7(b) is a photograph of the metal powder compact in the first region at this stage, taken from above. In this figure, the dark colored parts are the metal powder compacts and the light colored parts are the through holes.

[0085] The gold paste was applied to the through holes corresponding to the second region, dried, and then the gold powder was removed. The gold paste application method and drying conditions were the same as those in the first process.

[0086] Finally, the gold film on the surface of the remaining resist was removed by etching, and the resist was peeled off. As a result, a conductive bonding material having a metal powder compact in the first and second regions was produced. FIG. 8 shows an appearance photograph (FIG. 8(a)) from above of the conductive bonding material produced in this example, and a cross-sectional photograph (FIG. 8(b)) of the center of the pattern. The first and second regions are very close to each other, with a gap of about 0.5 μm. The conductive bonding material is essentially a continuous film. In this example, the minimum dimension L1 of the snake pattern part, which is the first region, is the line width of the pattern, which is 20 μm. The second region is the gap between the patterns, and its minimum dimension L2 is 20 μm (L1 / L2=1). Regarding the flatness of the conductive bonding material, the average thickness was 11 μm, and the maximum amount of gouging was 3 μm. Since the ratio of the maximum amount of gouging to the average thickness was 27%, it was confirmed that the flatness of the conductive bonding material of this example was good.

[0087] [Reference example] As a reference example, the application and drying of metal paste was performed in two stages based on a pattern referring to the conventional technology (Patent Document 3). In this reference example, as shown in FIG. 9(a), rectangular (20 μm×20 μm) metal powder compacts were formed at intervals of 4 μm using the same base material and gold paste as in the example. The same gold paste was then applied to fill the gaps in the formed metal powder compacts and dried. The method of forming the metal powder compacts at this time was basically the same as in the example.

[0088] FIG. 9(b) is a cross-sectional photograph of the conductive bonding material of the reference example obtained after the second gold paste was applied and dried. As shown in the figure, the gold powder is filled near the surface of the metal powder compact, so it can be said that the conductive bonding material is flat and has no gaps on the surface. However, the metal powder is not filled to the bottom of the gaps, so the gaps at the interface with the substrate remain as they are. The gaps in the conductive bonding material of this reference example are 4 μm, which is not very large, but if the area of ​​the conductive bonding material is increased, the proportion of the gaps will also increase, and there is a concern that the heat dissipation will decrease accordingly. It is considered necessary to form an appropriate gap (5 μm or more) when forming a metal powder compact using metal paste in two stages.

[0089] [Bonding test] A semiconductor chip bonding test was carried out using the bonding member manufactured in the above-mentioned embodiment. Here, based on the embodiment explained above with reference to FIG. 6(b), the conductive bonding material of the bonding member was bonded and transferred to the semiconductor chip, which was then bonded to a substrate. First, a Si chip (plate thickness 0.525 mm×2 mm□) was transferred as the semiconductor chip to the conductive bonding material of the bonding member. Metal films of Ti (thickness 50 nm), Pt (thickness 50 nm), and Au (thickness 200 nm) were previously formed on the bonding surface of the Si chip.

[0090] After placing the Si chip on the conductive bonding material, the conductive bonding material was transferred to the Si chip by pressing and heating. The heating conditions for this transfer process were a substrate side temperature of 200°C and a semiconductor chip side temperature of 200°C. The pressure was 1.7 MPa and applied for 10 minutes. After heating and pressing, the Si chip and the transferred conductive bonding material were picked up.

[0091] The Si chip was placed on a substrate and bonded to the substrate via the conductive bonding material by pressing and heating. The heating conditions for this bonding process were a substrate side temperature of 250° C. and a semiconductor chip side temperature of 250° C. The pressure was 1.7 MPa and applied for 60 minutes.

[0092] After the semiconductor chips were bonded in the above process, the shear strength of the bonded portion was measured. The shear strength was measured using a die shear measuring device at a shear speed of 100 μm / s and a step back interval of 100 μm, and the shear load was divided by the area of ​​the semiconductor chip (2 mm square). As a result, the shear strength of the bonded portion in the example was about 10 MPa, and it was confirmed that sufficient bond strength was obtained. [Industrial Applicability]

[0093] As described above, the conductive bonding material according to the present invention is divided into a first region and a second region formed by applying and forming a metal paste in two stages, but the gap between them is extremely narrow, and the conductive bonding material is essentially a continuous film. The conductive bonding material according to the present invention can be made large in area, even though it uses a metal paste as a precursor. The present invention exhibits excellent heat dissipation and conductivity as a conductive bonding material applied to die bonding and flip chip mounting of semiconductor elements to substrates. [Explanation of symbols]

[0094] 1. Substrate (substrate) 2. Resist 3. Photomask 4 Through hole (first area) 5 Interlayer 6 Metal Paste 7 Metal powder compact (first area) 8 Metal Film 9 Through hole (second area) 10 Metal powder compact (second area) 11 Conductive bonding materials 12 Joining materials C. Joined material (semiconductor chip) S Device Board

Claims

1. In a conductive bonding material comprising a metal powder compact having a predetermined area formed on a substrate, The metal powder constituting the compact is a powder made of one or more metals selected from the group consisting of gold, silver, platinum, and palladium having a purity of 99.9 mass% or more and having an average particle size of 0.005 μm or more and 1.0 μm or less, The conductive bonding material is divided into a first region and a second region that is a remaining region in a plan view, a minimum dimension L1 of the first region and a minimum dimension L2 of the second region are both 5 μm or more, and a ratio L1 / L2 of L1 to L2 is 0.25 or more and 4 or less; Furthermore, the conductive bonding material is characterized in that, in a cross-sectional view, a gap between the first region and the second region is less than 1 μm.

2. 2. The conductive bonding material according to claim 1, wherein the minimum dimension L1 of the first region and the minimum dimension L2 of the second region are 140 [mu]m or less.

3. 3. The conductive bonding material according to claim 1, wherein the first region is formed in a regular pattern of two or more successive unit squares each having a side length of the minimum dimension L1.

4. 3. The conductive bonding material according to claim 1, wherein the first region is formed in a regular pattern of continuous curves having a line width of a minimum dimension L1.

5. A bonding member comprising a substrate and the conductive bonding material according to claim 1 or 2.

6. 6. The bonding member according to claim 5, further comprising an undercoat film made of a metal or a metal oxide and / or an intermediate film made of a metal or a metal oxide between the substrate and the conductive bonding material.

7. 3. The method for producing a conductive bonding material according to claim 1 or 2, wherein a metal paste containing metal powder having an average particle size of 0.005 μm or more and 1.0 μm or less and made of one or more metals selected from the group consisting of gold, silver, platinum, and palladium having a purity of 99.9 mass% or more is used, Coating the substrate surface with a resist; a first step of forming a first through hole in a region corresponding to a first region of the resist, filling the first through hole with the metal paste, and then forming a compact of the metal powder contained in the metal paste; a second step of forming a second through hole in a region corresponding to the second region of the resist after the first step, filling the second through hole with the metal paste, and then forming a molded body of the metal powder contained in the metal paste; removing residual resist; A method for producing a conductive bonding material comprising the steps of:

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