Method for manufacturing conjugant, method for manufacturing semiconductor device, and semiconductor device

Abstract

To provide a method for manufacturing a conjugant formed by jointing a first member and a second member without generating void or exfoliation on the conjugant, a method for manufacturing a semiconductor device with the conjugant, and a semiconductor device with the conjugant.SOLUTION: A method for manufacturing a conjugant includes: a step ST1 of preparing a first member and a second member; a step ST2 of forming a metal paste film on the first member; a step ST3 of locating a mask jig, on which a through hole is formed, on the first member, where the mask jig is located on the first member, so that the metal paste film is positioned in the through hole; a step ST4 of performing first heat treatment for drying the metal paste film; a step ST5 of arranging the second member on the first member in contact with the metal paste film; and a step ST6 of performing second heat treatment for sintering the metal paste film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a bonded body, a method for manufacturing a semiconductor device, and a semiconductor device. [Background technology]

[0002] Conventionally, a bonding method is known in which a bonding material, which is a bonding material made by incorporating metal particles in an organic solvent (organic component), is sintered to bond one member to another. In this bonding method, a phenomenon is known in which voids are generated in the bonding material due to the evaporation of the organic solvent during sintering at high temperatures. The voids generated in the bonding material may adversely affect the bonding strength.

[0003] One way to prevent voids from occurring is to dry the bonding material, which contains organic solvents, at low temperatures for long periods of time. This method is said to be effective when the bonding area is relatively small (for example, a few square millimeters). On the other hand, when the bonding area is relatively large (for example, more than about 10 square millimeters), it becomes difficult to volatilize (dry) the organic solvent present near the center of the bonding material, so it is necessary to set a longer drying time for the bonding material. This increases the time required for bonding, which is one of the factors that reduces production efficiency.

[0004] On the other hand, in order to bond the bonding material and the members by sufficiently adhering them to each other at the interface between them, it is desirable that the organic solvent does not volatilize completely before the temperature reaches a high temperature at which the metal particles can be sintered. The organic solvent present near the center of the bonding material is less likely to volatilize, whereas the organic solvent present in the peripheral portion of the bonding material is more likely to volatilize.

[0005] For this reason, when the bonding area is relatively large, if the time for drying the bonding material is set long, the organic solvent present on the outer periphery of the bonding material will almost entirely evaporate, and peeling may occur on the outer periphery of the bonding material. To address this problem, Patent Document 1 proposes a method of applying the bonding material to be used as the bonding material multiple times. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5012239 (JP 2008-311371 A) Summary of the Invention [Problem to be solved by the invention]

[0007] The inventors evaluated conventional techniques and found that, when the bonding area is relatively large, it is still difficult to satisfactorily bond one component to another component without causing voids and peeling in the bonding material.

[0008] The present disclosure has been made to solve such problems, and one object is to provide a method for manufacturing a bonded body in which a first member and a second member are bonded without causing voids and peeling in a bonding material having a relatively large bonding area, another object is to provide a method for manufacturing a semiconductor device including such a bonded body, and yet another object is to provide a semiconductor device including such a bonded body. [Means for solving the problem]

[0009] The manufacturing method of the bonded body according to the present disclosure is a manufacturing method of a bonded body in which a first member and a second member are bonded with a bonding material, and includes the following steps: A first member having a conductive first bonding portion to which the bonding material will be bonded is prepared. A second member having a conductive second bonding portion to which the bonding material will be bonded is prepared. A paste-like conductive film in which metal particles are contained in an organic solvent is formed at the first bonding portion of the first member. A mask jig having a through hole is prepared, and the mask jig is placed on the first member. With the mask jig placed on the first member, a first heat treatment is performed on the conductive film at a first temperature lower than a temperature at which the metal particles start to sinter. The mask jig is removed from the first member, and the second member is placed on the first member in a manner that the second bonding portion of the second member contacts an upper surface of the conductive film. A second heat treatment is performed on the conductive film at a second temperature higher than the first temperature and equal to or higher than a temperature at which the metal particles start to sinter, thereby sintering the metal particles, thereby forming a bonded body in which the first member and the second member are bonded with the conductive film as a bonding material. In the process of placing the mask jig on the first member, the mask jig is placed on the first member in such a manner that the conductive film is positioned within the through hole, the side surface of the conductive film is surrounded by the wall surface of the through hole, and the upper surface of the conductive film is exposed.

[0010] The manufacturing method of the semiconductor device according to the present disclosure is a manufacturing method of a semiconductor device including a bonded body, and the step of forming the bonded body includes the following steps: preparing a first member having a conductive first bonding portion to which a bonding material will be bonded; preparing a second member having a conductive second bonding portion to which a bonding material will be bonded; forming a paste-like conductive film in which metal particles are contained in an organic solvent at the first bonding portion of the first member; preparing a masking tool having a through hole, and placing the masking tool on the first member; performing a first heat treatment on the conductive film at a first temperature lower than a temperature at which the metal particles start to sinter while the masking tool is placed on the first member; removing the masking tool from the first member, and placing the second member on the first member in a manner that the second bonding portion of the second member contacts the upper surface of the conductive film; performing a second heat treatment on the conductive film at a second temperature higher than the first temperature and equal to or higher than a temperature at which the metal particles start to sinter, thereby forming a bonded body in which the first member and the second member are bonded together using the conductive film as a bonding material. In the process of placing the mask jig on the first member, the mask jig is placed on the first member in such a manner that the conductive film is positioned within the through hole, the side surface of the conductive film is surrounded by the wall surface of the through hole, and the upper surface of the conductive film is exposed.

[0011] The semiconductor device according to the present disclosure is a semiconductor device including a bonded body, the bonded body including a first member, a second member, and a bonding material. The first member has a conductive first bonding portion. The second member has a conductive second bonding portion. The bonding material includes a first bonding material that is interposed between the first bonding portion and the second bonding portion and bonds the first member and the second member by being bonded to the first bonding portion and the second bonding portion. The distribution of the proportion of voids in a cross section of the bonding material in the thickness direction decreases from a first proportion to a second proportion lower than the first proportion from a side surface of the bonding material toward the inside of the bonding material. Effect of the Invention

[0012] According to the manufacturing method of the bonded body according to the present disclosure, a mask jig having a through hole is used, and a first heat treatment is performed to dry the conductive film in a state where the mask jig is placed on the first member in such a manner that the conductive film is positioned in the through hole, the side surface of the conductive film is surrounded by the wall surface of the through hole, and the upper surface of the conductive film is released. Then, a second heat treatment is performed to sinter the conductive film. This suppresses the volatilization of the organic solvent from the side surface of the conductive film, and allows the organic solvent to be uniformly volatilized from the upper surface of the conductive film to dry the conductive film. As a result, in the bonded body after the second heat treatment is performed on the conductive film, it is possible to suppress the occurrence of voids and peeling in the bonding material having a relatively large area.

[0013] According to the manufacturing method of the semiconductor device of the present disclosure, a mask jig having a through hole is used, and a first heating process is performed to dry the conductive film in a state where the mask jig is placed on a first member in such a manner that the conductive film is positioned in the through hole, the side surface of the conductive film is surrounded by the wall surface of the through hole, and the upper surface of the conductive film is released. Then, a second heating process is performed to sinter the conductive film. This suppresses the volatilization of the organic solvent from the side surface of the conductive film, and allows the organic solvent to be uniformly volatilized from the upper surface of the conductive film to dry the conductive film. As a result, in a semiconductor device including a bonded body after the second heating process is performed on the conductive film, it is possible to suppress the occurrence of voids and peeling in a bonding material having a relatively large area.

[0014] In the semiconductor device according to the present disclosure, the distribution of the ratio of pores in a cross section in the thickness direction of the bonding material bonding the first member and the second member decreases from a first ratio to a second ratio lower than the first ratio from the side surface of the bonding material toward the inside of the bonding material, thereby making it possible to suppress the occurrence of voids and peeling in the bonding material having a relatively large area. [Brief description of the drawings]

[0015] [Figure 1] FIG. 4 is a flowchart showing a method for manufacturing a bonded body according to the first embodiment. [Diagram 2]FIG. 4 is a cross-sectional view showing a step of a method for manufacturing a bonded body in the embodiment. [Diagram 3] 3 is a cross-sectional view showing a step performed after the step shown in FIG. 2 in the embodiment. [Figure 4] 4 is a plan view showing a step performed after the step shown in FIG. 3 in the embodiment. FIG. [Diagram 5] 5 is a cross-sectional view taken along line VV in FIG. 4 in the embodiment. [Figure 6] 6 is a cross-sectional view showing a step performed after the step shown in FIG. 4 and FIG. 5 in the embodiment. [Figure 7] 7 is a cross-sectional view showing a step performed after the step shown in FIG. 6 in the embodiment. [Figure 8] 8 is a cross-sectional view showing a step performed after the step shown in FIG. 7 in the embodiment. [Figure 9] FIG. 13 is a flowchart showing a method for manufacturing a bonded body according to a comparative example. [Figure 10] 5 is a cross-sectional view showing a step of a method for manufacturing a bonded body according to a comparative example. FIG. [Figure 11] 11 is a cross-sectional view showing a step performed after the step shown in FIG. [Figure 12] 12 is a cross-sectional view showing a step performed after the step shown in FIG. [Figure 13] 13 is a cross-sectional view showing a step performed after the step shown in FIG. 12. [Figure 14] 14 is a cross-sectional view showing a step performed after the step shown in FIG. 13. [Figure 15] FIG. 11 is a cross-sectional view for illustrating how an organic solvent volatilizes in a first heat treatment in a manufacturing method of a bonded body according to a comparative example. [Figure 16] 11A and 11B are diagrams including scanning electron microscope images showing voids and peeling that occurred in the bonding material in a bonded structure manufactured by a manufacturing method according to a comparative example. [Figure 17] FIG. 11 is a cross-sectional view for illustrating how an organic solvent volatilizes in a first heat treatment in a manufacturing method of a bonded body according to another comparative example. [Figure 18] FIG. 2 is a perspective view showing an example of a mask jig in the embodiment. [Figure 19] 19 is a cross-sectional view taken along line XIX-XIX in FIG. 18 in the embodiment. [Figure 20] FIG. 4 is a cross-sectional view showing a step of performing a first heating treatment by heat transfer heating in the embodiment. [Figure 21] FIG. 2 is a cross-sectional view for explaining how an organic solvent volatilizes in a first heat treatment in the embodiment. [Figure 22] FIG. 2 is a cross-sectional view for explaining a structure of a mask jig in the embodiment. [Figure 23] 10 is a cross-sectional view showing a state in which an organic solvent is condensed on a mask jig when a first heat treatment is performed in the embodiment; FIG. [Figure 24] FIG. 11 is a diagram showing the relationship between the time of the first heat treatment and the remaining amount of the organic solvent, and an ultrasonic inspection image showing voids and peeling that have occurred after the second heat treatment in this embodiment. [Diagram 25] FIG. 13 shows a photograph of the appearance of a metal paste film after a first heat treatment, an ultrasonic inspection image of the bonding material after a second heat treatment, and a scanning electron microscope image of a cross section of the bonding material, along with a comparative example, in this embodiment. [Figure 26] FIG. 13 is a diagram showing the distribution of the drying speed of an organic solvent after a first heat treatment for a mask jig including a mask jig according to a modified example in the embodiment. [Figure 27] FIG. 13 is a perspective view showing a mask jig according to a first modified example in the embodiment. [Figure 28] 28 is a cross-sectional view taken along line XXVIII-XXVIII in FIG. 27 in the embodiment. [Figure 29] FIG. 13 is a perspective view showing a mask jig according to a second modified example in the embodiment. [Diagram 30] 30 is a cross-sectional view taken along line XXX-XXX shown in FIG. 29 in this embodiment. [Diagram 31] FIG. 13 is a perspective view showing a mask jig according to a third modified example in the embodiment. [Diagram 32] FIG. 32 is a cross-sectional view taken along the cross-sectional line XXXII-XXXII shown in FIG. 31 in this embodiment. [Diagram 33] FIG. 13 is a perspective view showing a mask jig according to a fourth modified example in the embodiment. [Diagram 34] FIG. 34 is a cross-sectional view taken along line XXXIV-XXXIV shown in FIG. 33 in this embodiment. [Diagram 35] 10 is a cross-sectional view showing a step of a method for producing a bonded body according to the second embodiment. FIG. [Diagram 36] FIG. 11 is a first cross-sectional view illustrating a flow of hot air within a through hole in the mask jig in the embodiment. [Figure 37] FIG. 11 is a second cross-sectional view illustrating the flow of hot air within a through hole in the mask jig in the embodiment. [Figure 38] FIG. 2 is a perspective view showing a mask jig in the embodiment. [Figure 39] FIG. 39 is a cross-sectional view taken along line XXXIX-XXXIX in FIG. 38 in the embodiment. [Diagram 40] FIG. 2 is a top view showing a mask jig in the embodiment. [Diagram 41] FIG. 13 is a top view showing a mask jig according to a modified example in the embodiment. [Diagram 42] FIG. 13 is a top view showing a mask jig according to another modified example in the embodiment. [Diagram 43] FIG. 13 is a top view showing a mask jig according to still another modified example in the embodiment. [Diagram 44] FIG. 10 includes a graph showing the proportion of pores in a bonding material in each embodiment. [Diagram 45] FIG. 4 includes a scanning electron microscope image of a cross section of a bonding material after a second heat treatment in each embodiment. [Diagram 46] FIG. 11 is a top view showing a first example of a semiconductor device according to a third embodiment. [Figure 47]FIG. 47 is a cross-sectional view taken along line XLVII-XLVII shown in FIG. 46 in the embodiment. [Figure 48] FIG. 13 is a diagram showing an example of a flowchart of a method for manufacturing a semiconductor device in the embodiment. [Figure 49] FIG. 11 is a top view showing a second example of the semiconductor device in the embodiment. [Figure 50] FIG. 50 is a cross-sectional view taken along line LL in FIG. 49 in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Embodiment 1 An example of a method for producing the bonded body according to embodiment 1 will be described below. First, a process flow (flowchart) will be described.

[0017] As shown in FIG. 1, in step ST1, a first member and a second member are prepared. The first member has a first bonding portion to which a bonding material is bonded. Next, in step ST2, a metal paste film is formed on the first member as a paste-like conductive film that serves as the bonding material. Next, in step ST3, a mask jig having a through hole formed therein is placed on the first member. The mask jig is placed on the first member so that the metal paste film is positioned in the through hole.

[0018] Next, in step ST4, a first heating process is performed to dry the metal paste film. Next, in step ST5, a second member is placed on the first member. The second member has a second bonding portion to which a bonding material is bonded. The second member is placed on the first member so that the metal paste film contacts the second bonding portion. Next, in step ST6, a second heating process is performed to sinter the metal paste film. Through this second heating process, a bonded body in which the first member and the second member are bonded is manufactured.

[0019] Next, an example of a method for manufacturing a bonded body based on the above-mentioned process flow will be specifically described. As shown in FIG. 2, a first member 5 is prepared. At this time, a second member 9 (see FIG. 7) is also prepared. The first member 5 may be a substrate made of a metal such as copper or aluminum. The first member 5 may also be a substrate whose base material is ceramic or resin. The first member 5 has a first bonding portion 7 to which a bonding material will be bonded.

[0020] The first bonding portion 7 is conductive. When the first member 5 is a substrate formed from a metal, the first bonding portion 7 may be a portion of the substrate itself. When the first member 5 is a substrate whose base material is ceramic or the like, the first bonding portion 7 may be a structure in which a metal such as copper, aluminum, silver, or gold is formed on the surface of the substrate by plating or the like.

[0021] The second member 9 may be a conductive element including a portion made of a metal such as copper or aluminum. The second member 9 may also be a semiconductor element including a portion made of a ceramic or the like. The second member has a second bonding portion 11 to which a bonding material will be bonded.

[0022] The second bonding portion 11 is conductive. When the second member 9 is a conductive element, the second bonding portion 11 may be a portion itself formed of a metal such as copper or aluminum. When the second member 9 is a semiconductor element, the second bonding portion 11 may be a structure in which a metal such as copper, aluminum, silver, or gold is formed by plating or the like on a portion formed of ceramic or the like.

[0023] Next, as shown in Fig. 3, a metal paste film 13 is formed on the first bonding portion 7 of the first member 5. The metal paste film 13 is a bonding material in which metal particles are contained in an organic solvent (organic component), and is formed, for example, by a dispensing method or a printing method. The bonding material may be a low-temperature sintering type metal paste that utilizes a low-temperature sintering phenomenon due to the quantum size effect of metal particles and high surface activity. The bonding material may also be a solder paste that is prepared by heating and melting a metal such as tin and using liquid phase diffusion bonding.

[0024] Next, as shown in Figs. 4 and 5, a mask jig 21 is placed on the first member 5. A through hole 25 is formed in the mask jig 21 so as to penetrate the mask jig 21. When the mask jig 21 is placed on the first member 5, the metal paste film 13 is located in the through hole 25 of the mask jig 21. A side surface 13b of the metal paste film 13 is surrounded by a wall surface 25c of the through hole 25. An upper surface 13a of the metal paste film 13 is open. The function and effect of the mask jig 21 will be described in detail later.

[0025] Next, as shown in FIG. 6, a first heating process is performed on the metal paste film 13. At this time, as described later, the first heating process is performed by heat conduction heating. The temperature of the first heating process is, for example, about 80° C. to 120° C. The first heating process is performed, for example, in an air atmosphere or a nitrogen atmosphere. Since the metal paste film 13 is located in the through-hole 25 of the mask jig 21, the organic solvent volatilizes from the upper surface 13a of the metal paste film 13. The metal paste film 13 is dried by the volatilization of the organic solvent. Thereafter, the mask jig 21 is removed from the first member 5.

[0026] Next, as shown in FIG. 7, the second member 9 is placed on the first member 5 in such a manner that the second bonding portion 11 of the second member 9 is in contact with the metal paste film 13. Next, as shown in FIG. 8, a second heat treatment is performed on the metal paste film 13. The second heat treatment is performed at a temperature equal to or higher than the temperature at which the metal particles start to sinter. The temperature of the second heat treatment is, for example, about 200° C. to 300° C. Furthermore, the second heat treatment is preferably performed in a nitrogen atmosphere, but may be performed in an air atmosphere, a reduced pressure environment, or a vacuum environment.

[0027] The second heat treatment volatilizes the organic solvent remaining in the metal paste film 13, and sinters the metal particles. As a result, the metal paste film 13 becomes a bonding material 17 (sintered film), and the first bonding portion 7 and the second bonding portion 11 are bonded together. In this way, the bonded body 1 in which the first member 5 and the second member 9 are bonded together by the bonding material 17 is manufactured as a sintered product.

[0028] In the above-mentioned method for manufacturing the bonded body 1, a mask jig 21 is used in the first heat treatment for drying the metal paste film 13. This makes it possible to suppress the occurrence of voids and peeling. This will be described in comparison with a method for manufacturing a bonded body according to a comparative example. A process flow (flowchart) according to the comparative example is shown in Fig. 9, and specific manufacturing steps are shown in Figs. 10 to 14.

[0029] First, in step CT1 (see FIG. 9), a first member 105 having a first bonding portion 107 is prepared as shown in FIG. 10. Also, a second member 109 having a second bonding portion 111 is prepared (see FIG. 13). Next, in step CT2 (see FIG. 9), a metal paste film 113 serving as a bonding material is formed on the first bonding portion 107 of the first member 105 as shown in FIG. 11. Next, in step CT3 (see FIG. 9), a first heat treatment is performed on the metal paste film 113 as shown in FIG. 12, and the metal paste film 113 is dried.

[0030] Next, in step CT4 (see FIG. 9), the second member 109 is placed on the first member 105 in such a manner that the second bonding portion 111 of the second member 109 is in contact with the metal paste film 113, as shown in FIG. 13. Next, in step CT5 (see FIG. 9), a second heat treatment is performed on the metal paste film 113 to sinter the metal particles. As a result, the metal paste film 113 becomes a bonding material 117 (sintered film), as shown in FIG. 14, and the first bonding portion 107 and the second bonding portion 111 are bonded together. In this manner, the bonded body 101 according to the comparative example is manufactured.

[0031] 15, in the manufacturing method of bonded body 101 according to the comparative example, the first heat treatment for drying metal paste film 113 is performed in a state in which upper surface 113a and side surface 113b of metal paste film 113 are exposed (step CT3). As a result, the organic solvent is more likely to volatilize in the outer periphery of metal paste film 113 where upper surface 113a and side surface 113b of metal paste film 113 are exposed than in the portion of metal paste film 113 located more inward than the outer periphery.

[0032] For this reason, the degree of drying of the metal paste film (the amount of remaining organic solvent) varies within the surface of the metal paste film 113. As a result, in the bonded body 101 manufactured through the second heat treatment, it was confirmed that voids 211 were generated in the bonding material 117, as shown in the upper part of Fig. 16. In addition, it was confirmed that peeling 213 occurred at the outer periphery of the bonding material 117, as shown in the lower part of Fig. 16.

[0033] As another manufacturing method according to the comparative example, after forming a metal paste film on a first member, a second member is placed on the first member and a heat treatment corresponding to the second heat treatment is performed without performing the first heat treatment. In this case, as shown in FIG. 17, the organic solvent can only volatilize from the side surface of the metal paste film 113. As a result, the organic solvent remains in the center of the bonding material. Furthermore, the volatilization of the organic solvent causes voids to occur in the bonding material.

[0034] In contrast to the method for manufacturing a bonded body according to the comparative example, in the method for manufacturing a bonded body according to the first embodiment, a mask jig 21 is used when performing the first heat treatment. The inventors have found that by drying the metal paste film 13 using the mask jig 21, the amount of organic solvent contained in the metal paste film 13 can be uniformly reduced within the surface of the metal paste film 13 from the initial amount to a desired amount range. In other words, they have found that the drying speed within the surface of the metal paste film 13 can be made uniform. They have found that by performing the second heat treatment (sintering heating) in this state, no voids are generated in the bonding material 17, and no peeling occurs at the outer periphery of the bonding material 17. This will be explained step by step.

[0035] First, the structure of the mask jig 21 will be described. As shown in Fig. 18 and Fig. 19, the mask jig 21 is a frame 27 in which a through hole 25 is formed. The mask jig 21 has a first main surface 23a and a second main surface 23b that face each other. The first main surface 23a comes into contact with the first member 5. The second main surface 23b comes into contact with the second member 9.

[0036] Through hole 25 is formed from first main surface 23a toward second main surface 23b. Through hole 25 has an opening shape corresponding to the planar shape of metal paste film 13 formed in first bonding portion 7. Here, through hole 25 is formed having a rectangular opening shape corresponding to rectangular metal paste film 13. Through hole 25 is formed to have a constant opening area from first main surface 23a to second main surface 23b.

[0037] 20, in the first heating treatment, with mask jig 21 placed on first member 5, metal paste film 13 is dried by heat transfer from hot plate 51. At this time, mask jig 21 is placed on first member 5 in such a manner that metal paste film 13 is located in through hole 25 of mask jig 21, side surface 13b of metal paste film 13 is surrounded by wall surface 25c of through hole 25, and upper surface 13a of metal paste film 13 is exposed. This suppresses volatilization of the organic solvent from side surface 13b and the like of metal paste film 13.

[0038] As a result, as shown in Fig. 21, the organic solvent contained in the metal paste film 13 volatilizes more uniformly from the upper surface 13a of the metal paste film 13, and the organic solvent can be uniformly reduced to a desired amount (remaining amount) within the surface of the metal paste film 13. Thereafter, the second heat treatment is performed when the remaining amount of the organic solvent is at the desired remaining amount. As a result, it was confirmed that the generation of voids can be suppressed in the central portion of the bonding material 17, which has a relatively wide bonding area. It was also confirmed that peeling of the bonding material 17 can be suppressed in the outer periphery of the bonding material 17.

[0039] Next, the mask jig 21 that regulates (controls) the direction in which the organic solvent volatilizes will be described in detail. First, the positional relationship between the mask jig 21 and the metal paste film 13 will be described. As shown in FIG. 22, first, in one cross section of the mask jig 21 arranged on the first member 5, the length (length of one side) of the through hole 25 is set to D. The length (length of one side) of the metal paste film 13 located inside the through hole 25 is set to d. Then, it is desirable that the length D and the length d have the following length relationship.

[0040] d≦D≦MIN(d+1.0mm, d+0.1×d) Here, for MIN(a, b), if a≦b, then MIN(a, b)=a. If a>b, then MIN(a, b)=b.

[0041] Also, when there is no problem even if the mask jig 21 contacts the metal paste film 13 and a part of the metal paste film 13 is transferred, the length relationship may be D < d. It is desirable that the length D (opening size) of the through hole 25 is set to the same length from the first main surface 23a to the second main surface 23b. In addition, in order to control the volatilization of the organic solvent from the outer peripheral portion of the metal paste film 13, for example, a mask jig 21 in which a tapered through hole 25 is formed may be used. This will be described later as a variation of the mask jig 21.

[0042] Next, the height of the mask jig 21 will be described. Let the height of the mask jig 21 be H. Let the maximum value of the length (length of one side) of the metal paste film be dmax. The height H and the length dmax preferably have the following length relationship.

[0043] H ≧ dmax Also, depending on the atmosphere during the first heat treatment, the following length relationship may be present.

[0044] H ≧ 1 / (2dmax) For example, in the case of the metal paste film 13 with a side length of 10 mm square and a film thickness of about 0.1 mm, the height H of the mask jig 21 is set to about 10 mm. Let the thickness of the frame 27 be W. Regarding the thickness W, there are no particular restrictions, and it is appropriately set from the viewpoints of the process and the like.

[0045] The arrangement relationship between the mask jig 21 and the metal paste film 13 will be described in more detail. As described above, in the first heat treatment, the metal paste film 13 formed on the surface of the first member 5 and the mask jig 21 arranged so as to surround the metal paste film 13 are heated from the back surface of the first member 5 by the hot plate 51.

[0046] Therefore, a temperature difference ΔT occurs between the temperature of mask jig 21 and the temperature of metal paste film 13. For example, the temperature of the atmosphere is T0. In the first heat treatment, the target temperature of metal paste film 13 is T3, and the average temperature of mask jig 21 is T5. Then, the temperature relationship is T0 <T5<T3となる。

[0047] Here, consider the case where the temperature difference ΔT (T3-T5) between the temperature T5 of mask jig 21 and the temperature T3 of metal paste film 13 becomes large. The temperature T5 of mask jig 21 is lower than the temperature T3 of metal paste film 13. For this reason, when the temperature difference ΔT becomes large, the organic solvent (vapor) volatilized from metal paste film 13 tends to condense on the wall surface of mask jig 21, as shown in the dotted line frame DW in FIG.

[0048] If the organic solvent condenses on the wall surface of mask jig 21, the portion of metal paste film 13 located in the vicinity of the condensed organic solvent becomes more likely to dry, and there is a risk that metal paste film 13 may dry unevenly.

[0049] Therefore, in order to suppress the temperature difference between the temperature of the mask jig 21 and the temperature of the metal paste film 13, it is desirable that the first main surface 23a of the mask jig 21 and the surface of the first member 5 are in contact with each other without any gaps. Furthermore, if the thickness of the metal paste film 13 is t and the local gap is Δ, the local gap Δ may be Δ≦t. A material having a small heat capacity and high thermal conductivity is desirable as the material of the mask jig 21. For example, an aluminum-based metal is more desirable than an iron-based metal as the material of the mask jig 21.

[0050] Next, the relationship between the time for which the first heat treatment is performed in the first heat treatment (drying) and the amount of organic solvent remaining in metal paste film 13 will be described. By performing the first heat treatment on metal paste film 13, the organic solvent contained in metal paste film 13 volatilizes. As shown in the upper part of FIG. 24, the amount of organic solvent contained in metal paste film 13 decreases from the amount of organic solvent initially contained (100%) over the time of the first heat treatment. At this time, the organic solvent volatilizes faster in the outer periphery of metal paste film 13 (see dashed line graph) than in the center of metal paste film 13 (see solid line graph).

[0051] Here, if the first heat treatment is insufficient, for example, when the amount of organic solvent remaining in metal paste film 13 is m% or more (range SV1), voids are likely to occur in the sintered bonding material due to the evaporation of the remaining organic solvent in the second heat treatment, as shown in the lower left side of Fig. 24. On the other hand, if the first heat treatment is excessively performed, for example, when the amount of organic solvent remaining in metal paste film 13 is n% or less (range SV3), metal paste film 13 becomes too dry, as shown in the lower right side of Fig. 24, and the sintered bonding material and the second bonding portion of the second member do not adhere to each other in the second heat treatment, and peeling is likely to occur at the interface.

[0052] In the manufacturing method of bonded body 1 according to the first embodiment, a first heating process is performed in a state in which mask jig 21 is placed on first member 5. The first heating process is performed in a state in which side surface 13b of metal paste film 13 is surrounded by wall surface 25c of through hole 25 and upper surface 13a of metal paste film 13 is exposed. This allows the organic solvent contained in metal paste film 13 to volatilize evenly from upper surface 13a of metal paste film 13, and the organic solvent can be reduced more evenly within the surface of metal paste film 13 to a desired amount (residual amount).

[0053] That is, the amount of the organic solvent to be retained is set to fall within the range (range SV2) where no voids are generated and no peeling of the interface occurs in the second heat treatment. Specifically, as shown in the upper part of FIG. 24, the maximum amount of the organic solvent to be retained is set to an amount lower than m% of the initial amount (maximum amount % < m%). On the other hand, the minimum amount of the organic solvent to be retained is set to an amount higher than n% of the initial amount (minimum amount % > n%).

[0054] By performing the second heat treatment with the remaining amount of the organic solvent contained in the metal paste film 13 being this amount, generation of voids can be suppressed in the sintered bonding material (sintered film) in which the metal paste film 13 is sintered. Also, peeling of the bonding material can be prevented from occurring.

[0055] The inventors evaluated joining a square silicon chip (side length 10 mm) as the second member to a copper substrate as the first member using a commercially available metal paste film. The evaluation results are shown in FIG. 25.

[0056] As shown in FIG. 25, in the case of the comparative example without using the mask jig, in the metal paste film 13 that was dried by performing the first heat treatment, it was found that the remaining amount of the organic solvent was small at the outer peripheral portion of the metal paste film 13. In the bonding material (sintered film) that was subjected to the second heat treatment after the first heat treatment, generation of voids was observed. Also, it was found that peeling occurred at the outer peripheral portion of the bonding material.

[0057] On the other hand, in the case of the embodiment using the mask jig 21, in the metal paste film 13 that was dried by performing the first heat treatment, it was found that there was almost no portion where the remaining amount of the organic solvent was small compared to the case of the comparative example. In the bonding material 17 (sintered film) that was subjected to the second heat treatment after the first heat treatment, it was found that no voids or peeling occurred.

[0058] According to the evaluation by the inventors, it was found that the amount of organic solvent remaining in the metal paste film 13 after the first heat treatment is 80% for m and 50% for n. In other words, it was found that the amount of organic solvent remaining in the first heat treatment is preferably 50%<remaining amount<80% of the initial amount (100%). Thus, it was found that the manufacturing method of the bonded body 1 described above can bond the first member 5 and the second member 9 without causing voids and peeling in the bonding material 17 (sintered film) having a relatively wide bonding area.

[0059] (Modification of mask jig) As described above, it was found that by performing the first heat treatment on metal paste film 13 using mask jig 21, the organic solvent can be uniformly evaporated within the surface of metal paste film 13. In other words, it was found that the drying speed within the surface of metal paste film 13 can be made uniform.

[0060] The following describes the distribution of the drying speed within the surface of the metal paste film 13. As shown in Fig. 26, the distribution of the drying speed of the metal paste film 13 by the first heat treatment was evaluated in the cases where the above-mentioned mask jig was used and where the mask jig was not used, by dividing the metal paste film 13 into nine regions R1 to R9 in a matrix (3 x 3).

[0061] Regions R1, R3, R7, and R9 are regions located at the corners (four corners) of metal paste film 13. Region R2 is a region located between regions R1 and R3. Region R4 is a region located between regions R1 and R7. Region R6 is a region located between regions R3 and R9. Region R8 is a region located between regions R7 and R9. Region R5 is a region located in the center of metal paste film 13. In addition, the drying speed of the metal paste film in the first heat treatment was evaluated into five stages ranging from fast to slow, with 1 being a fast drying speed and 5 being a slow drying speed.

[0062] When metal paste film 13 was evaluated without using a mask jig, the drying speed of region R5 was 3, the drying speed of regions R2, R4, R6, and R8 was 2, and the drying speed of regions R1, R3, R7, and R9 was 1. In contrast, when metal paste film 13 was evaluated with a mask jig, the drying speed of region R5 was 4, the drying speed of regions R2, R4, R6, and R8 was 4, and the drying speed of regions R1, R3, R7, and R9 was 3.

[0063] Next, mask jigs 21 (21a to 21d) that have the basic shape of the above-mentioned mask jig 21 and that can adjust the distribution of the drying speed within the surface of metal paste film 13 will be described as variations of mask jig 21.

[0064] (First Modification) 27 and 28, in the mask jig 21a according to the first modification, the opening shape of the through hole 25 on the first main surface 23a side has an opening shape that faces the planar shape of the metal paste film formed in the first bonding portion. The through hole 25 is formed in such a manner that the opening cross-sectional area decreases from the first main surface 23a toward the second main surface 23b. That is, the through hole 25 is formed to have an inverse tapered shape from the first main surface 23a toward the second main surface 23b.

[0065] 26, in mask jig 21a according to the first modified example, the drying speed of regions R1, R2, R3, R4, R6, R7, R8, and R9 was found to be 5. As a result, in mask jig 21a according to the first modified example, the drying speed of the outer periphery of metal paste film 13 can be made slower than in the case of basic mask jig 21.

[0066] (Second Modification) 29 and 30, in the mask jig 21b according to the second modification, the opening shape of the through hole 25 on the first main surface 23a side has an opening shape corresponding to the planar shape of the metal paste film formed on the first bonding portion. The through hole 25 is formed in such a manner that the opening cross-sectional area increases from the first main surface 23a toward the second main surface 23b. That is, the through hole 25 is formed to have a forward tapered shape from the first main surface 23a toward the second main surface 23b.

[0067] 26, in mask jig 21b according to the second modified example, the drying speed of regions R1, R2, R3, R4, R6, R7, R8, and R9 was found to be 3. As a result, in mask jig 21b according to the second modified example, the drying speed of the outer periphery of metal paste film 13 can be made faster than in the case of basic mask jig 21.

[0068] (Third Modification) 31 and 32, in a mask jig 21 according to the third modification, a through hole 25 has a first through portion 33 and a second through portion 35. The first through portion 33 has an opening shape corresponding to the planar shape of the metal paste film 13, and is formed from the first main surface 23a toward the second main surface 23b.

[0069] The second through portion 35 communicates with the first through portion 33 and opens to the second main surface 23b. The opening cross-sectional area of ​​the second through portion 35 is smaller than the opening cross-sectional area of ​​the first through portion 33. The second through portion 35 is formed with an overhang portion 37 that protrudes inward from the wall surface of the first through portion 33.

[0070] 26, in mask jig 21c according to the third modified example, the drying speed of regions R1, R2, R3, R4, R6, R7, R8, and R9 was found to be 5. As a result, in mask jig 21c according to the third modified example, the drying speed of the outer periphery of metal paste film 13 can be made slower than in the case of basic mask jig 21.

[0071] (Fourth Modification) 33 and 34, in mask jig 21d according to the fourth modification, through hole 25 has first through portion 33 and second through portion 35. First through portion 33 has an opening shape corresponding to the planar shape of metal paste film 13, and is formed from first main surface 23a toward second main surface 23b.

[0072] The second through portion 35 communicates with the first through portion 33 and opens to the second main surface 23b. The opening cross-sectional area of ​​the second through portion 35 is smaller than the opening cross-sectional area of ​​the first through portion 33. The second through portion 35 is formed with a protrusion 39 that protrudes inward from a corner of the first through portion 33.

[0073] 26, in mask jig 21d according to the fourth modified example, the drying speed of regions R1, R3, R7, and R9 was found to be 5. As a result, in mask jig 21d according to the fourth modified example, the drying speed of the portion (corner) of the metal paste film located directly below protrusion 39 can be made slower than in the case of basic mask jig 21.

[0074] Considering the above evaluation results, by selecting the shape of mask jig 21 according to the actual manufacturing conditions of the bonded body, it is possible to control the distribution of the drying speed of metal paste film 13 in the first heat treatment, i.e., the distribution of the remaining amount of organic solvent, and thus optimize the process for manufacturing bonded body 1.

[0075] Embodiment 2 An example of a manufacturing method of a bonded body according to the second embodiment will be described. In the first embodiment, heat transfer heating from a hot plate 51 is given as an example of a technique (heating method) of the first heat treatment for drying the metal paste film 13. Here, as another example of the technique (heating method) of the first heat treatment, for example, a case where convection heating by circulating hot air from a drying furnace is applied will be described. Note that a series of manufacturing processes other than the heating method of the first heat treatment are performed according to the process flow shown in FIG. 1.

[0076] First, after steps ST1 and ST2 (see FIG. 1), in step ST3, mask jig 21e is placed on first member 5 so that metal paste film 13 is positioned in through hole 25 (see FIG. 35). Mask jig 21e has mesh structure 29 (see FIG. 36, etc.) formed thereon. The structure of mask jig 21e will be described later.

[0077] Next, in step ST4, a first heat treatment is performed by convection heating. As shown in Fig. 35, the first member 5 on which the mask jig 21e is placed is conveyed (see arrow) by a conveyor belt 53 in the production line, while hot air 65 is blown onto the metal paste film 13 and the like. At this time, since the mesh structure 29 is formed on the mask jig 21e, the metal paste film 13 can be uniformly dried. Thereafter, through steps ST5 and ST6, the bonded body 1 is manufactured.

[0078] In the above-described method for manufacturing the bonded body 1 using convection heating, first, a conveying mechanism such as the conveyor belt 53 is combined to continuously convey the first member 5 on which the mask jig 21e is placed. This enables more uniform production management on-site and improves production efficiency.

[0079] Furthermore, in the manufacturing method of the bonded body 1 to which convection heating is applied, the metal paste film 13 can be uniformly dried by using a mask jig 21e having a mesh structure 29 (see FIG. 36, etc.) formed thereon as the mask jig 21. This will be described.

[0080] As described above, in the first heating process, the organic solvent contained in metal paste film 13 volatilizes due to heating. When metal paste film 13 is dried by heat conduction heating, the volatilized organic solvent (vapor) is carried to the periphery of metal paste film 13 by the driving forces of thermal convection caused by the temperature difference between metal paste film 13 and the temperature of the atmosphere surrounding metal paste film 13, and diffusion caused by the concentration difference of the vapor. The speed at which the volatilized organic solvent is carried affects the speed at which the organic solvent contained in metal paste film 13 dries.

[0081] On the other hand, when drying metal paste film 13 by convection heating, in addition to the above-mentioned thermal convection and diffusion, forced convection due to the flow of hot air is used as a driving force to transport the volatilized organic solvent to the periphery of metal paste film 13. At this time, the speed at which the volatilized organic solvent is transported affects the speed at which the organic solvent contained in metal paste film 13 dries.

[0082] In this case, in the first heating process (see FIG. 35), it is possible to control the overall way in which hot air is applied to the first member 5 on which the mask jig 21 is placed, but it is expected that eddies will occur locally in the flow of hot air. It is also expected that the flow of hot air will become turbulent. As a result, it is expected that the flow of hot air inside the through hole 25 of the mask jig 21 will become unstable.

[0083] As shown in Fig. 36, when main flow 61b of hot air flows diagonally downward from above, it is assumed that vortex 63a and the like are generated in through hole 25 in the direction indicated by the arrow due to the position of through hole 25 and main flow 61a. On the other hand, as shown in Fig. 37, when main flow 61b of hot air flows diagonally upward from below, it is assumed that vortex 63b and the like are generated in through hole 25 in the direction indicated by the arrow due to the position of through hole 25 and main flow 61b. In these cases, there are regions where the convection speed is relatively fast and regions where it is slow near the surface of metal paste film 13, which may cause variation in the drying speed (volatilization of organic solvent).

[0084] 38, 39 and 40, in order to suppress the generation of eddies of hot air or the like in through-hole 25, a mask jig 21e having a mesh structure 29 formed on the second main surface 23b side of through-hole 25 is used as mask jig 21. A plurality of openings 31, each having a rectangular opening shape, are formed in a matrix pattern in mesh structure 29. The structure of mask jig 21e other than mesh structure 29 is similar to that of mask jig 21 shown in Figs. 18 and 19, so the same members are denoted by the same reference numerals, and description thereof will not be repeated unless necessary.

[0085] In mask jig 21e, mesh structure 29 is formed, so that main flows 61a, 61b of hot air are blocked from the flow of hot air in through hole 25, and the flow of hot air in through hole 25 can be stabilized. This allows metal paste film 13 to be uniformly dried. As a result, after the second heat treatment, it is possible to prevent voids from being generated in bonding material 17, as in the case of embodiment 1. Also, it is possible to prevent bonding material 17 from peeling off.

[0086] On the first main surface 23a side of the mask jig 21e, the through hole 25 has an opening shape corresponding to the planar shape of the metal paste film 13 (first bonding portion 7). For example, when a rectangular power semiconductor element having a relatively large area, such as an IGBT (Insulated Gate Bipolar Transistor), is mounted on the first member 5, it is desirable to make the opening shape of the through hole 25 rectangular. Also, when the shape of the first bonding portion 7 is, for example, a circular or donut shape (annular), it is desirable to make the opening shape of the through hole 25 circular or donut shape.

[0087] As shown in FIG. 39, in a cross-section of the mask jig 21e provided with the mesh structure 29, let the length (side length) of the through hole 25 be D. Let the length (side length) of the metal paste film 13 located in the through hole 25 be d. Then, it is desirable that the length D and the length d have the following length relationship, similar to the case of the mask jig 21 (see FIG. 22) described above.

[0088] d ≦ D ≦ MIN(d + 1.0 mm, d + 0.1×d) Also, when there is no problem even if the mask jig 21e contacts the metal paste film 13 and a part of the metal paste film 13 is transferred, the length relationship may be D < d. The length D (opening size) of the through hole 25 is preferably set to the same length from the first main surface 23a to the mesh structure 29. Further, as described above, in order to control the volatilization of the organic solvent from the outer peripheral portion of the metal paste film 13, for example, a mask jig 21e in which a tapered through hole 25 is formed may be used.

[0089] Regarding the mesh structure 29, when the length (opening size) of the opening 31 is r (see FIG. 40), it is desirable that the length r is, for example, approximately r ≦ 1.0 mm. Depending on the speed of the main flow 61a of the hot air 65, etc., r ≦ 2.0 mm may also be acceptable. Also, when the thickness of the mesh structure 29 is h, it is desirable that the thickness h is, for example, h ≦ r or h ≦ 1.0 mm.

[0090] By the mesh structure 29, the flow of the hot air in the through hole 25 in the mask jig 21e is blocked from the main flow 61a of the hot air, etc. If the maximum value of the length (side length) of the metal paste film is dmax, the height H and the length dmax may have the following length relationship, similar to the case of the mask jig 21 (see FIG. 22) described above.

[0091] H ≧ 1 / (2dmax) As in the case of the mask jig 21 (see FIG. 22) described above, if the thickness of the frame 27 is W, there is no particular restriction on the thickness W, and it is set appropriately from the viewpoint of the process, etc. Furthermore, the shape of the openings 31 of the mesh structure 29 is not limited to a rectangular shape. As shown in FIG. 41, the openings 31 may have a circular opening shape. Moreover, the arrangement pattern of the openings 31 may be a staggered arrangement.

[0092] Furthermore, the openings 31 of the mesh structure 29 are not limited to a uniform size and shape, and the size of the openings may be changed in order to change the area of ​​the openings depending on the position in the plane of the metal paste film 13. As shown in Fig. 42, the size of the substantially rectangular opening 31 located near the center of the mesh structure 29 may be set larger than the size of the openings 31 located on the periphery. Also, as shown in Fig. 43, the size of the circular opening 31 located near the center of the mesh structure 29 may be set larger than the size of the openings 31 located on the periphery.

[0093] By increasing the opening size of the openings 31 located near the center of the mesh structure 29, the drying speed of the organic solvent in the portion located near the center of the metal paste film 13 can be made faster than the drying speed of the organic solvent in the portion located on the periphery. In this way, the distribution of the drying speed of the organic solvent within the surface of the metal paste film 13 can be appropriately adjusted to a desired distribution by changing the opening size of the openings 31 in the mesh structure 29, etc.

[0094] (Conjugate structure) The structure of the bonded body manufactured by the manufacturing method for the bonded body explained in the first and second embodiments will be described.

[0095] A first member 5 having a first bonding portion 7 and a second member 9 having a second bonding portion 11 are bonded together by a bonding material 17 (sintered film) obtained by sintering (second heat treatment) a metal paste film 13. At this time, the metal paste film 13 is sintered (second heat treatment) in a state in which the metal paste film has been dried (first heat treatment) in advance using a mask jig 21.

[0096] When the second heat treatment (sintering) is performed on the metal paste film 13, the organic solvent remaining in the metal paste film 13 volatilizes, forming spaces in the bonding material 17. Here, spaces less than about 0.5 mm in size that will not cause defects are referred to as holes. On the other hand, spaces greater than about 0.5 mm in size that may cause defects are referred to as voids.

[0097] Next, the pores formed in the bonding material 17 will be described. Fig. 44 shows a profile of the porosity in the bonding material 17 (sintered film) of the bonded body 1. Fig. 45 shows a scanning electron microscope image of a cross section of the bonded body 1. The porosity is the ratio (proportion) of the area of ​​the pores to the area of ​​a cross section of the bonding material 17.

[0098] In the second heat treatment (sintering), the outer periphery including the side surfaces of the metal paste film 13 is directly exposed to the atmosphere, so the organic solvent evaporates faster, and the porosity is h% (10%). On the other hand, the portion of the metal paste film 13 located inside the outer periphery is sandwiched between the first member 5 (first bonding portion 7) and the second member 9 (second bonding portion 11), so the organic solvent evaporates slower, and the porosity is k% (1%).

[0099] The porosity tends to decrease rapidly from the outer periphery (side surface) of the bonding material 17 toward the inner region (see Figs. 44 and 45). The porosity decreases rapidly from h% (10%) to k% (1%) within a distance range of, for example, about 0.1 mm to 1 mm from the side surface of the bonding material 17. In this case, the gradient of the change in porosity is about 50% / mm, which means that the porosity changes by about 10% over a distance of 0.2 mm. Note that these numerical values ​​are merely examples and will vary depending on the size of the bonding material 17, the material of the bonding material 17, etc.

[0100] Embodiment 3 Here, a semiconductor device manufactured by applying the manufacturing method for the bonded body described in the first embodiment and the like will be described.

[0101] (Example 1) A semiconductor device 71 according to a first example will be described. As shown in Fig. 46 and Fig. 47, in the semiconductor device 71 as the bonded body 1, a second bonding portion 11 of a power semiconductor chip 75 as the second member 9 is bonded to a first bonding portion 7 of a substrate 73 as the first member 5 by a first bonding material 17a. In the power semiconductor chip 75, a third bonding portion 12 is formed on the surface opposite to the surface on which the second bonding portion 11 is formed. A fourth bonding portion 19 of a lead terminal 77 as the third member 18 is bonded to the third bonding portion 12 of the power semiconductor chip 75 by a second bonding material 17b.

[0102] Next, as an example of a method for manufacturing the above-mentioned semiconductor device 71, a case in which the manufacturing method described in the first embodiment is applied to both the first bonding material 17a and the second bonding material 17b will be described with reference to a flowchart.

[0103] As shown in FIG. 48, in step FC1, a first metal paste film that will become the first bonding material 17a is formed on the first bonding portion 7 of the substrate 73 (see FIG. 3). Next, in step FC2, a first mask jig is placed on the substrate 73 (see FIGS. 4 and 5). In step FC3, a second metal paste film that will become the second bonding material 17b is formed on the first bonding portion 7 of the power semiconductor chip 75 (see FIG. 3). Next, in step FC4, a second mask jig is placed on the power semiconductor chip 75 (see FIGS. 4 and 5).

[0104] Next, in step FC5, a first heat treatment is performed by heat conduction heating on the first metal paste film surrounded by the first mask jig and the second metal paste film surrounded by the second mask jig, and the first metal paste film and the second metal paste film are each dried. After that, the first mask jig and the second mask jig are removed. Next, in step FC6, the power semiconductor chip 75 is placed on the substrate 73 so that the second bonding portion 11 of the power semiconductor chip 75 contacts the dried first metal paste film.

[0105] Next, in step FC7, lead terminals 77 are placed on power semiconductor chip 75 so that the second joint portions of lead terminals 77 come into contact with the dried second metal paste film. Next, in step FC8, a second heating process is performed with power semiconductor chip 75, lead terminals 77, etc. placed on substrate 73 to sinter the first metal paste film and the second metal paste film. In this way, semiconductor device 71 is completed as joint body 1, as shown in Figs. 46 and 47.

[0106] In the semiconductor device 71 according to the first example, by applying the manufacturing method of the bonded body described in the first embodiment and the like, it is possible to suppress the peeling of the first bonding material 17a and the second bonding material 17b. Also, it is possible to suppress the generation of voids in the first bonding material 17a and the second bonding material 17b. As a result, it is possible to more firmly bond the power semiconductor chip 75 having a relatively large area to the substrate 73. Also, it is possible to more firmly bond the lead terminal 77 to the power semiconductor chip 75. As described above, in each of the first bonding material 17a and the second bonding material 17b, the porosity tends to rapidly decrease from the outer periphery (side surface) of each of the first bonding material 17a and the second bonding material 17b toward the inner region (see FIG. 44 and the like).

[0107] In the above-described method for manufacturing a semiconductor device, the power semiconductor chip 75 and the lead terminals 77 are joined by sintering a metal paste film. The method for joining the power semiconductor chip 75 and the lead terminals 77 is not limited to this, and they may be joined by using solder, for example.

[0108] In addition, as the first heating process in the manufacturing method of the semiconductor device 71 described above, a case has been described in which the first heating process utilizes heat transfer heating. However, it is also possible to perform the first heating process (drying) using convection heating as described in embodiment 2.

[0109] (Example 2) A semiconductor device 81 according to the second example will be described. As shown in Fig. 49 and Fig. 50, in the semiconductor device 81 as the bonded body 1, a second bonding portion 11 of a semiconductor package 85 as the second member 9 is bonded to a first bonding portion 7 of a heat sink 83 as the first member 5 by a bonding material 17. In the semiconductor package 85, a semiconductor element 87 is sealed with a sealing resin 89. A lead terminal 91 electrically connected to the semiconductor element 87 protrudes from the sealing resin 89.

[0110] Next, an example of a method for manufacturing the above-mentioned semiconductor device 81 will be described based on the process flow (flowchart) shown in FIG. 1, which has been described in the first embodiment.

[0111] First, in step ST1, a heat sink 83 is prepared as the first member 5. Also, a semiconductor package 85 is prepared as the second member 9. Next, in step ST2, a metal paste film that will become the bonding material 17 is formed on the first bonding portion 7 of the heat sink 83 (see FIG. 3). Next, in step ST3, a mask jig is placed on the heat sink 83 (see FIGS. 4 and 5). Next, in step ST4, a first heating process is performed on the metal paste film by heat transfer heating, and the metal paste film is dried. Thereafter, the mask jig is removed.

[0112] Next, in step ST5, the semiconductor package 85 as the second member is placed on the heat sink 83 so that the second bonding portion 11 of the semiconductor package 85 contacts the dried metal paste film. Next, in step ST6, the metal paste film is subjected to a second heat treatment to sinter the metal paste film. In this way, the semiconductor device 81 as the bonded body 1 shown in Figs. 49 and 50 is completed.

[0113] In the semiconductor device 81 according to the second example, by applying the manufacturing method of the bonded body described in the first embodiment, peeling can be suppressed at the interface between the bonding material 17 and the second bonding portion 11 of the semiconductor package 85. Also, generation of voids in the bonding material 17 can be suppressed. As a result, the semiconductor package 85 having a relatively large area can be more firmly bonded to the heat sink 83. Also, heat generated in the semiconductor package 85 can be more efficiently conducted to the heat sink 83. As described above, the porosity of the bonding material 17 shows a tendency to rapidly decrease from the outer periphery (side surface) of the bonding material 17 toward the inner region (see FIG. 44, etc.).

[0114] As the first heating process in the manufacturing method of the semiconductor device 81 described above, the first heating process using heat conduction heating has been described. However, it is also possible to perform the first heating process (drying) using convection heating as described in embodiment 2.

[0115] The methods for manufacturing a bonded body and methods for manufacturing a semiconductor device described in the respective embodiments can be variously combined as necessary.

[0116] The embodiments disclosed herein are illustrative and are not limited thereto. The present disclosure is not limited to the above-described scope, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0117] The present disclosure includes the following aspects.

[0118] [Appendix 1] A method for manufacturing a bonded body in which a first member and a second member are bonded with a bonding material, comprising the steps of: preparing the first member having a conductive first bonding portion to which the bonding material is to be bonded; preparing the second member having a conductive second bonding portion to which the bonding material is to be bonded; forming a paste-like conductive film, which is made by incorporating metal particles in an organic solvent, on the first bonding portion of the first member; preparing a mask jig having a through hole and placing the mask jig on the first member; performing a first heat treatment on the conductive film at a first temperature that is lower than a temperature at which the metal particles start to sinter while the mask jig is placed on the first member; removing the mask jig from the first member, and placing the second member on the first member in such a manner that the second bonding portion of the second member contacts an upper surface of the conductive film; a step of performing a second heat treatment on the conductive film at a second temperature that is higher than the first temperature and is equal to or higher than a temperature at which the metal particles start to sinter, thereby sintering the metal particles, thereby forming the bonded body in which the first member and the second member are bonded together using the conductive film as the bonding material; Equipped with A method for manufacturing a bonded body, wherein in the process of placing the mask jig on the first member, the mask jig is placed on the first member in such a manner that the conductive film is positioned within the through hole, the side of the conductive film is surrounded by the wall surface of the through hole, and the top surface of the conductive film is released.

[0119] [Appendix 2] In the step of performing the first heat treatment, the organic solvent contained in the conductive film is volatilized, thereby drying the conductive film; The method for manufacturing a bonded body according to claim 1, wherein the time for drying the conductive film is set to a time that does not cause voids to be generated in the bonding material and does not cause peeling of the bonding material after the conductive film that has been subjected to the first heating treatment is subjected to the second heating treatment.

[0120] [Appendix 3] In the step of preparing a mask jig, A first main surface that will contact the first member; a second main surface opposite to the first main surface; having 3. The method for manufacturing a bonded body according to claim 1, wherein a mask jig is prepared, the through hole being formed so as to penetrate the mask jig from the first main surface to the second main surface.

[0121] [Appendix 4] In the step of preparing a mask jig, The method for manufacturing a bonded body according to claim 3, wherein the mask jig is prepared so that the through hole extends from the first main surface to the second main surface and has an opening shape corresponding to a planar shape of the conductive film formed at the first bonding portion.

[0122] [Appendix 5] In the step of preparing a mask jig, the mask jig is prepared such that, on the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed on the first bonding portion, and an opening cross-sectional area of ​​the through hole decreases from the first main surface toward the second main surface.

[0123] [Appendix 6] In the step of preparing a mask jig, the mask jig is prepared such that, on the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed on the first bonding portion, and an opening cross-sectional area of ​​the through hole increases from the first main surface toward the second main surface.

[0124] [Appendix 7] In the step of preparing a mask jig, The through hole is In the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed in the first bonding portion, and a first through portion extending from the first main surface toward the second main surface; a second penetration portion communicating with the first penetration portion and opening to the second main surface; having 4. The method for manufacturing a bonded body according to claim 3, wherein the mask jig is provided with an eave portion that protrudes inward from a wall surface of the through hole in the second through portion.

[0125] [Appendix 8] In the step of preparing a mask jig, The through hole is In the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed in the first bonding portion, and a first through portion extending from the first main surface toward the second main surface; a second penetration portion communicating with the first penetration portion and opening to the second main surface; having The method for manufacturing a bonded body described in Appendix 3, wherein the mask jig is prepared such that, at the corner portion of the second through portion, a protrusion is formed that protrudes inward from a wall surface of the through hole.

[0126] [Appendix 9] 9. The method for producing a bonded body according to any one of claims 1 to 8, wherein in the step of performing the first heat treatment, the conductive film is heated by heat conduction heating.

[0127] [Appendix 10] 9. The method for producing a bonded body according to any one of claims 1 to 8, wherein in the step of performing the first heat treatment, the conductive film is heated by convection heating.

[0128] [Appendix 11] 11. The method for manufacturing a bonded body according to claim 10, wherein in the step of preparing a mask jig, the mask jig is prepared in which a mesh structure having an opening is formed in the through hole.

[0129] [Appendix 12] 12. The method for manufacturing a bonded body according to claim 11, wherein in the step of preparing a mask jig, the mask jig is prepared, on which the mesh structure including the openings having different opening sizes is formed.

[0130] [Appendix 13] A method for manufacturing a semiconductor device including a bonded body, comprising the steps of: The step of forming the bonded body includes: preparing a first member having a conductive first bonding portion to which a bonding material is to be bonded; preparing a second member having a conductive second bonding portion to which the bonding material is to be bonded; forming a paste-like conductive film, which is made by incorporating metal particles in an organic solvent, on the first bonding portion of the first member; preparing a mask jig having a through hole and placing the mask jig on the first member; performing a first heat treatment on the conductive film at a first temperature that is lower than a temperature at which the metal particles start to sinter while the mask jig is placed on the first member; removing the mask jig from the first member, and placing the second member on the first member in such a manner that the second bonding portion of the second member contacts an upper surface of the conductive film; a step of performing a second heat treatment on the conductive film at a second temperature that is higher than the first temperature and is equal to or higher than a temperature at which the metal particles start to sinter, thereby sintering the metal particles, thereby forming the bonded body in which the first member and the second member are bonded together using the conductive film as the bonding material; Equipped with A method for manufacturing a semiconductor device, wherein in the process of placing the mask jig on the first member, the mask jig is placed on the first member in such a manner that the conductive film is positioned within the through hole, the side of the conductive film is surrounded by the wall surface of the through hole, and the top surface of the conductive film is released.

[0131] [Appendix 14] In the step of performing the first heat treatment, the organic solvent contained in the conductive film is volatilized, thereby drying the conductive film; The method for manufacturing a semiconductor device according to claim 13, wherein the time for drying the conductive film is set such that, after the conductive film that has been subjected to the first heating treatment is subjected to the second heating treatment, no voids are generated in the bonding material and no peeling occurs in the bonding material.

[0132] [Appendix 15] The method for manufacturing a semiconductor device according to claim 13 or 14, wherein in the step of preparing the first member, the first member includes a substrate having a conductive material located on at least a surface of the first joint portion.

[0133] [Appendix 16] 16. The method for manufacturing a semiconductor device according to any one of claims 13 to 15, wherein in the step of preparing the second member, the second member includes either a conductive element or a semiconductor element. [Industrial Applicability]

[0134] INDUSTRIAL APPLICABILITY The present disclosure is effectively utilized in a manufacturing method for manufacturing a bonded body by sintering a paste-like conductive film in which metal particles are contained in an organic solvent. [Explanation of symbols]

[0135] 1 bonded body, 3 semiconductor device, 5 first member, 7 first bonding portion, 9 second member, 11 second bonding portion, 12 third bonding portion, 13 metal paste film, 13a upper surface, 13b side surface, 17 bonding material, 17a first bonding material, 17b second bonding material, 18 third member, 19 fourth bonding portion, 21, 21a, 21b, 21c, 21d, 21e mask jig, 23a first main surface, 23b second main surface, 25 through hole, 25c wall surface, 27 frame, 29 mesh structure, 31 opening, 33 first through portion, 35 second through portion, 37 eaves portion, 39 protrusion portion, 51 hot plate, 53 conveyor belt, 55 roller, 61a, 61b main flow, 63a, 63b flow, 65 hot air, 71 semiconductor device, 73 Substrate, 75 power semiconductor chip, 77 lead terminal, 81 semiconductor device, 83 heat sink, 85 semiconductor package, 87 semiconductor element, 89 sealing resin, 91 lead terminal, R1, R2, R3, R4, R5, R6, R7, R8, R9 area, r length, DW dotted frame.

Claims

1. A method for manufacturing a bonded body in which a first member and a second member are bonded with a bonding material, comprising the steps of: preparing the first member having a conductive first bonding portion to which the bonding material is to be bonded; preparing the second member having a conductive second bonding portion to which the bonding material is to be bonded; forming a paste-like conductive film, which is made by incorporating metal particles in an organic solvent, on the first bonding portion of the first member; preparing a mask jig having a through hole and placing the mask jig on the first member; performing a first heat treatment on the conductive film at a first temperature that is lower than a temperature at which the metal particles start to sinter while the mask jig is placed on the first member; removing the mask jig from the first member, and placing the second member on the first member in such a manner that the second bonding portion of the second member contacts an upper surface of the conductive film; a step of subjecting the conductive film to a second heat treatment at a second temperature that is higher than the first temperature and equal to or higher than a temperature at which the metal particles start to sinter, thereby forming the bonded body in which the first member and the second member are bonded together using the conductive film as the bonding material by sintering the metal particles; Equipped with A method for manufacturing a joint, wherein in the process of placing the mask jig on the first member, the mask jig is placed on the first member in such a manner that the conductive film is positioned within the through hole, the side of the conductive film is surrounded by the wall surface of the through hole, and the top surface of the conductive film is released.

2. In the step of performing the first heat treatment, the organic solvent contained in the conductive film is volatilized, thereby drying the conductive film; 2. The method for manufacturing a bonded body according to claim 1, wherein the time for drying the conductive film is set such that, after the conductive film that has been subjected to the first heat treatment is subjected to the second heat treatment, no voids are generated in the bonding material and no peeling occurs in the bonding material.

3. In the step of preparing a mask jig, A first main surface that will contact the first member; a second main surface opposite to the first main surface; having The method for manufacturing a bonded body according to claim 1 , wherein the mask jig is prepared so that the through hole is formed to penetrate the mask jig from the first main surface to the second main surface.

4. In the step of preparing a mask jig, 4. The method for manufacturing a bonded body according to claim 3, wherein the mask jig is prepared so that the through hole extends from the first main surface to the second main surface and has an opening shape corresponding to the planar shape of the conductive film formed at the first bonding portion.

5. In the step of preparing a mask jig, 4. The method for manufacturing a bonded body according to claim 3, wherein the mask jig is prepared such that, on the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed on the first bonding portion, and an opening cross-sectional area of ​​the through hole decreases from the first main surface toward the second main surface.

6. In the step of preparing a mask jig, 4. The method for manufacturing a bonded body according to claim 3, wherein the mask jig is prepared such that, on the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed on the first bonding portion, and an opening cross-sectional area of ​​the through hole increases from the first main surface toward the second main surface.

7. In the step of preparing a mask jig, The through hole is In the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed in the first bonding portion, and a first through portion extending from the first main surface toward the second main surface; a second penetration portion communicating with the first penetration portion and opening to the second main surface; having The method for manufacturing a bonded body according to claim 3 , wherein the mask jig is provided with an eave portion that protrudes inward from a wall surface of the through hole in the second through portion.

8. In the step of preparing a mask jig, The through hole is In the first main surface, the through hole has a first opening shape corresponding to a planar shape of the conductive film formed in the first bonding portion, and a first through portion extending from the first main surface toward the second main surface; a second penetration portion communicating with the first penetration portion and opening to the second main surface; having The method for manufacturing a bonded body according to claim 3 , wherein the mask jig is provided with a protrusion that protrudes inward from a wall surface of the through hole at a corner portion of the second through portion.

9. The method for producing a bonded body according to claim 1 , wherein in the step of performing the first heat treatment, the conductive film is heated by heat conduction heating.

10. The method for producing a bonded body according to claim 1 , wherein in the step of performing the first heat treatment, the conductive film is heated by convection heating.

11. The method for manufacturing a bonded body according to claim 10 , wherein in the step of preparing a mask jig, the mask jig is prepared in which a mesh structure having an opening is formed in the through hole.

12. The method for manufacturing a bonded body according to claim 11 , wherein in the step of preparing a mask jig, the mask jig is prepared on which the mesh structure including the openings having different opening sizes is formed.

13. A method for manufacturing a semiconductor device including a bonded body, comprising the steps of: The step of forming the bonded body includes: preparing a first member having a conductive first bonding portion to which a bonding material is to be bonded; preparing a second member having a conductive second bonding portion to which the bonding material is to be bonded; forming a paste-like conductive film, which is made by incorporating metal particles in an organic solvent, on the first bonding portion of the first member; preparing a mask jig having a through hole and placing the mask jig on the first member; performing a first heat treatment on the conductive film at a first temperature that is lower than a temperature at which the metal particles start to sinter while the mask jig is placed on the first member; removing the mask jig from the first member, and placing the second member on the first member in such a manner that the second bonding portion of the second member contacts an upper surface of the conductive film; a step of subjecting the conductive film to a second heat treatment at a second temperature that is higher than the first temperature and equal to or higher than a temperature at which the metal particles start to sinter, thereby forming the bonded body in which the first member and the second member are bonded together using the conductive film as the bonding material by sintering the metal particles; Equipped with A method for manufacturing a semiconductor device, wherein in the process of placing the mask jig on the first member, the mask jig is placed on the first member in such a manner that the conductive film is positioned within the through hole, the side of the conductive film is surrounded by the wall surface of the through hole, and the top surface of the conductive film is released.

14. In the step of performing the first heat treatment, the organic solvent contained in the conductive film is volatilized, thereby drying the conductive film; 14. The method for manufacturing a semiconductor device according to claim 13, wherein the time for drying the conductive film is set so as not to cause voids in the bonding material and not to cause peeling of the bonding material after the second heating treatment is performed on the conductive film that has been subjected to the first heating treatment.

15. 15. The method for manufacturing a semiconductor device according to claim 13, wherein in the step of preparing the first member, the first member includes a substrate having a conductive material located at least on a surface of the first bonding portion.

16. The method for manufacturing a semiconductor device according to claim 13 , wherein in the step of preparing the second member, the second member includes either a conductive element or a semiconductor element.

17. A semiconductor device including a junction, The conjugate is A first member having a conductive first joint; a second member having a conductive second joint; a bonding material including a first bonding material interposed between the first bonding portion and the second bonding portion and bonded to the first bonding portion and the second bonding portion to bond the first member and the second member; Equipped with A semiconductor device, wherein a distribution of the proportion of voids in a cross section of the bonding material in the thickness direction decreases from a first proportion to a second proportion lower than the first proportion from a side of the bonding material toward the inside of the bonding material.

18. the first member includes a substrate made of any one of a metal, a ceramic, and a resin; The semiconductor device according to claim 17 , wherein the second member includes one of a conductive element and a semiconductor element.

19. the second member has a conductive third joint portion, the joint body includes a third member having a conductive fourth joint portion, the bonding material includes a second bonding material that is interposed between the third bonding portion and the fourth bonding portion and is bonded to the third bonding portion and the fourth bonding portion to bond the second member and the third member, The semiconductor device according to claim 18 , wherein the third member includes a lead terminal.

20. the first member includes a heat sink; The semiconductor device according to claim 17 , wherein the second component includes a semiconductor package.

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