JP6566634B2 - Junction structure and manufacturing method of junction structure - Google Patents

Description

  The present invention relates to a bonded structure and a method for manufacturing the bonded structure.

  It is known that a plurality of members are integrated and joined by bringing a plurality of members into contact with each other and welding. Generally, fusion welding or brazing is known as welding.

  The fusion welding is performed by heating the boundary of the contacted member to a high temperature and dissolving it locally. However, when performing fusion welding, corrosion or fatigue deterioration may occur in the bonding region and its vicinity.

  In the brazing, the joining member is joined by melting the filler in a state in which the solder having a melting point lower than that of the joining member is filled between the joining members and then solidifying. By brazing, joining can be performed without dissolving the joining member itself. By using a hard brazing (for example, silver brazing and aluminum brazing) as a brazing brazing, it is possible to realize a joint having a relatively high mechanical strength (Patent Document 1). Patent Document 1 discloses a joined body in which a hard solder is filled in a gap between a ceramic and a metal tube to join the ceramic and the metal tube.

JP 2013-193094 A

  However, when brazing using a hard solder, it is necessary to heat to a high temperature exceeding 500 ° C. Further, when using aluminum brazing as a hard brazing, it is necessary to braze in a vacuum atmosphere, and it has not been possible to easily perform joining at a low temperature.

  This invention is made | formed in view of said subject, The objective is to provide the manufacturing method of the junction structure which can be favorably and easily joined also in a low-temperature environment, and a junction structure. is there.

  A bonded structure according to the present invention includes a semiconductor element, a wiring, and a metal film. The metal film joins the semiconductor element and the wiring. The metal constituting the metal film is diffused by stress migration.

  In one embodiment, the coefficient of thermal expansion of the material constituting the semiconductor element and / or the material constituting the wiring is lower than the coefficient of thermal expansion of the metal constituting the metal film.

  The joined structure according to the present invention includes a first member, a second member, and a metal film. The first member includes a metal member or an insulating member. The second member includes a metal member or an insulating member. The metal film joins the first member and the second member. The metal constituting the metal film is diffused by stress migration.

  In a certain embodiment, the thermal expansion coefficient of the material which comprises the said 1st member and / or the material which comprises the said 2nd member is lower than the thermal expansion coefficient of the metal which comprises the said metal film.

  In one embodiment, the metal film has a laminated structure in which a plurality of metal layers are laminated, and the plurality of metal layers are made of the same metal.

  In one embodiment, the crystal state of the metal constituting the metal film is a fine crystal or a columnar crystal.

  The bonded structure according to the present invention includes a first member, a thermal stress absorber, a second member, a first metal film, and a second metal film. The first member includes a metal member or an insulating member. The second member includes a metal member or an insulating member. The first metal film bonds the first member and the thermal stress absorber. The second metal film bonds the thermal stress absorbing material and the second member. At least one of the metal constituting the first metal film and the metal constituting the second metal film is diffused by stress migration.

  In one embodiment, the coefficient of thermal expansion of the material constituting the thermal stress absorbing material is lower than the coefficient of thermal expansion of the metal constituting the first metal film and the coefficient of thermal expansion of the metal constituting the second metal film. .

  In one embodiment, at least one of the first metal film and the second metal film has a stacked structure in which a plurality of metal layers are stacked, and the plurality of metal layers are made of the same metal. It is configured.

  In one embodiment, the crystal state of the metal constituting the first metal film and / or the metal constituting the second metal film is a fine crystal or a columnar crystal.

  In one embodiment, the thermal stress absorber is provided with a through hole or a depression.

  The method for manufacturing a bonded structure according to the present invention includes a step of preparing a laminated body in which a semiconductor element and a wiring are laminated through a metal film, and heating the laminated body to stress-migrate the metal constituting the metal film. And a bonding step of bonding the semiconductor element and the wiring.

  The method for manufacturing a bonded structure according to the present invention includes a step of preparing a laminate in which a first member including a metal member or an insulating member and a second member including a metal member or an insulating member are stacked via a metal film. And a bonding step of heating the laminated body, diffusing the metal constituting the metal film by stress migration, and bonding the first member and the second member.

  The manufacturing method of the joined structure according to the present invention includes a first member including a metal member or an insulating member, a thermal stress absorber, a second member including the metal member or the insulating member, the first member, and the thermal stress absorption. A step of preparing a laminate in which a first metal film positioned between a material and a second metal film positioned between the thermal stress absorbing material and the second member is prepared, and the first metal At least one of the film and the second metal film is heated, the metal constituting the first metal film and / or the second metal film is diffused by stress migration, and the first member and / or the second metal film is diffused. A joining step of joining the member and the thermal stress absorbing material.

  In one embodiment, the joining step includes a step of heating to a temperature of 100 ° C. or higher and 400 ° C. or lower.

  According to the present invention, it is possible to provide a bonded structure that can be bonded easily and easily even in a low temperature environment.

It is a mimetic diagram of an embodiment of a joined structure by the present invention. (A) is a figure which shows the SEM photograph of the heated silver film surface on a silicon substrate, (b) is the elements on larger scale of (a), (c) is sectional drawing of (b). . (A) And (b) is a schematic diagram for demonstrating the manufacturing method of the joining structure shown in FIG. (A)-(d) is a schematic diagram for demonstrating the manufacturing method of the joining structure of this embodiment. It is a schematic diagram of the junction structure of this embodiment. It is a schematic diagram of the junction structure of this embodiment. It is a mimetic diagram of an embodiment of a joined structure by the present invention. (A)-(e) is a schematic diagram for demonstrating the manufacturing method of the joining structure shown in FIG. It is a schematic diagram which shows an example of the thermal-stress absorber in the joining structure shown in FIG. It is a schematic diagram which shows another example of the thermal-stress absorption material in the joining structure shown in FIG. It is a schematic diagram which shows another example of the thermal-stress absorber in the joining structure shown in FIG. It is a mimetic diagram of an embodiment of a joined structure by the present invention. (A)-(d) is a schematic diagram for demonstrating the manufacturing method of the joining structure shown in FIG. (A) is the figure which showed the cross section of the silver film in which stress migration generate | occur | produced, (b) is the elements on larger scale of (a), (c) is the schematic diagram for demonstrating the stress migration of a metal It is. It is a schematic diagram for demonstrating joining by the stress migration of a metal. (A) is typical sectional drawing of the joining structure of Example 1, (b) is a perspective view of the joining structure of Example 1. FIG. (A) is a schematic diagram for demonstrating the structure of the joining structure of Example 2, (b) is a figure which shows the SEM photograph which expanded the area | region B of (a), (c) is (a) 2) is a view showing an SEM photograph in which a region C of FIG. (A) is a schematic diagram of the junction structure of Example 3, (b) is a diagram showing an SEM photograph in which the region B of (a) is enlarged, and (c) is a partially enlarged view of (b). It is.

  Embodiments of a bonded structure and a method for manufacturing the bonded structure according to the present invention will be described below. However, the present invention is not limited to the following embodiments, and the following embodiments may be appropriately changed. In order to avoid redundant description, overlapping descriptions may be omitted as appropriate, but the gist of the invention is not limited.

  With reference to FIG. 1, an embodiment of a bonded structure according to the present invention will be described. FIG. 1 shows a schematic diagram of a bonded structure 100 of the present embodiment. The bonded structure 100 includes a semiconductor element 110, a metal film 120, and a wiring 130. In the bonding structure 100, the semiconductor element 110, the metal film 120, and the wiring 130 are stacked in this order, and the metal film 120 bonds the semiconductor element 110 and the wiring 130 together.

  In the bonded structure 100 of the present embodiment, the metal constituting the metal film 120 diffuses due to stress migration, so that the semiconductor element 110 and the wiring 130 are bonded via the metal film 120. Specifically, when a stress gradient occurs in the metal film 120, the metal constituting the metal film 120 diffuses, and as a result, the bonded state is maintained. Stress migration occurs at any of the interface between the semiconductor element 110 and the metal film 120, the interface between the metal film 120 and the wiring 130, and the inside of the metal film 120.

  Bonding in the bonding structure 100 is realized by stress migration generated in the metal film 120. Stress migration is a material that has a high coefficient of thermal expansion as a result of a stress gradient generated in the material due to the difference in thermal expansion caused by the temperature change when the temperature changes while materials with different coefficients of thermal expansion are in contact with each other. This is a phenomenon in which these elements move. It is known that stress migration may cause defects (for example, voids or cracks) and cause failure of semiconductor devices and the like.

  The bonded structure 100 of the present embodiment realizes good bonding by using such stress migration. Specifically, when the temperature is changed while two kinds of materials having a large difference in thermal expansion coefficient are in contact with each other, a stress gradient is generated in the metal film 120. This gradient causes stress migration, and the metal of the metal film 120 diffuses so as to overflow from the surface. When the metal of the metal film 120 is diffused, the metal is integrated by filling an uneven gap at the interface between the semiconductor element 110 and the metal film 120, the interface between the metal film 120 and the wiring 130, or the interface inside the metal film 120. Thus, the semiconductor element 110 and the wiring 130 are favorably bonded by the metal film 120. Note that the occurrence of stress migration can be confirmed by photographing the junction cross section using an apparatus such as a scanning electron microscope (SEM). Further, in the formation of the bonding portion, the growth of the bonding necking can be promoted by forming nanoparticles or an amorphous nanostructure by a surface reaction in the bonding atmosphere.

  Until now, when joining two members, it was common to perform heat treatment (for example, sintering) at a high temperature. On the other hand, in the present embodiment, as described above, the semiconductor element 110 and the wiring 130 are bonded using stress migration of the metal constituting the metal film 120. Since stress migration occurs at a temperature lower than a general sintering temperature, the bonded structure 100 of the present embodiment can realize good bonding even in a low temperature environment. Further, even when the heat resistance of either the semiconductor element 110 or the wiring 130 is low, the semiconductor element 110 and the wiring 130 can be favorably bonded. In addition, since a large-scale apparatus such as a heating furnace is not required, bonding can be performed at a low cost with a simple process. Furthermore, bonding can be performed using inexpensive and versatile metals such as copper.

  Hereinafter, the semiconductor element 110, the metal film 120, and the wiring 130 constituting the bonded structure 100 will be described.

(Semiconductor element 110)
The material constituting the semiconductor element 110 is, for example, silicon, carbon, silicon carbide, gallium nitride, gallium nitride formed on silicon, silicon nitride, or aluminum nitride.

(Metal film 120)
The metal constituting the metal film 120 is, for example, copper, silver, zinc, gold, palladium, aluminum, nickel, cobalt, or iron. The metal constituting the metal film 120 is preferably copper, silver, zinc, aluminum, cobalt, or nickel in order to have a thermal expansion coefficient that is excellent in versatility and cost performance and can easily generate stress migration. . The thickness of the metal film 120 is preferably 0.5 μm or more and 30.0 μm or less in order to have excellent bonding strength and easily generate stress migration.

  The metal film 120 may be composed of a plurality of stacked metal layers. When the metal film 120 has a laminated structure, the metals constituting the plurality of metal layers may be the same type of metal or different types of metals. The metal diffused by the stress migration moves so as to fill the unevenness at the interface between the semiconductor element 110 and the metal film 120, the interface between the layers in the metal film 120, or the interface between the metal film 120 and the wiring 130.

The thermal expansion coefficient (linear expansion coefficient) of the metal constituting the metal film 120 is preferably higher than the thermal expansion coefficient (linear expansion coefficient) of the material constituting the semiconductor element 110. For example, the thermal expansion coefficient of the metal constituting the metal film 120 is 10.0 × 10 ⁻⁶ or more, and the thermal expansion coefficient of the material constituting the semiconductor element 110 is 0.1 × 10 ⁻⁶ or more and 10.0 × 10. Less than ^-6 . In particular, the ratio of the thermal expansion coefficient of the metal constituting the metal film 120 to the thermal expansion coefficient of the material constituting the semiconductor element 110 (the thermal expansion coefficient of the metal constituting the metal film 120 / the thermal expansion of the material constituting the semiconductor element 110). Ratio) is preferably 2.0 or more.

  The crystal state of the metal constituting the metal film 120 is preferably a fine crystal (a fine crystal state with a submicron unit) or a columnar crystal. When the crystal state is a columnar crystal, the metal constituting the metal film 120 diffuses along the surface or the crystal grain boundary, so that stress migration can be performed more easily than a metal having an equiaxed crystal with a coarse crystal state. It can be generated and the bonding state becomes good.

  In the bonded structure 100, a suitable combination of the material forming the semiconductor element 110 and the metal forming the metal film 120 (semiconductor element 110 / metal film 120) effectively generates stress migration and has a good bonding state. For example, gallium nitride / silver, silicon carbide / silver, gallium nitride / copper, or silicon carbide / copper.

(Wiring 130)
The material constituting the wiring 130 is, for example, copper, silver, zinc, gold, palladium, aluminum, niobium, nickel, cobalt, molybdenum, tungsten, titanium, or iron. The metal constituting the wiring 130 is preferably copper, iron, or silver in order to have a thermal expansion coefficient that is excellent in versatility and cost performance and can easily generate stress migration.

The thermal expansion coefficient (linear expansion coefficient) of the material forming the wiring 130 is preferably lower than the thermal expansion coefficient (linear expansion coefficient) of the metal forming the metal film 120 in order to improve bonding by stress migration. . For example, the thermal expansion coefficient of the material constituting the wiring 130 is 0.1 × 10 ⁻⁶ or more and less than 20.0 × 10 ⁻⁶ . In particular, the ratio of the thermal expansion coefficient of the material constituting the metal film 120 to the thermal expansion coefficient of the material constituting the wiring 130 (thermal expansion coefficient of the metal constituting the metal film 120 / thermal expansion coefficient of the material constituting the wiring 130). Is preferably 2.0 or more.

  In the bonded structure 100, a suitable combination of the metal forming the metal film 120 and the material forming the wiring 130 (metal film 120 / wiring 130) effectively generates stress migration and improves the bonding state. Thus, for example, silver / molybdenum, silver / tungsten, silver / niobium, silver / titanium, copper / molybdenum, copper / tungsten, copper / niobium, or copper / titanium.

  Hereinafter, an example of the thermal expansion coefficient of the material constituting the semiconductor element 110 and the thermal expansion coefficient of the material constituting the metal film 120 and the wiring 130 will be shown. Here, the thermal expansion coefficient is a linear expansion coefficient, and the unit of the thermal expansion coefficient is “1 / K”.

Example of coefficient of thermal expansion of material constituting semiconductor element 110 Silicon: 2.6 × 10 ⁻⁶
Silicon carbide: 3.7 × 10 ⁻⁶
Gallium nitride: 3.0 × 10 ⁻⁶
Silicon nitride: 3.0 × 10 ⁻⁶
Aluminum nitride: 5.0 × 10 ⁻⁶
Alumina: 7.2 × 10 ⁻⁶

Example of thermal expansion coefficient of metal constituting metal film 120 and wiring 130 Aluminum: 23.0 × 10 ⁻⁶
Iron: 12.0 × 10 ^-6
Cobalt: 13.0 × 10 ⁻⁶
Nickel: 12.8 × 10 ⁻⁶
Gold: 14.3 × 10 ⁻⁶
Copper: 16.8 × 10 ⁻⁶
Zinc: 30.2 × 10 ⁻⁶
Silver: 18.9 × 10 ⁻⁶
Palladium: 11.8 × 10 ⁻⁶
Tungsten: 4.5 × 10 ⁻⁶
Molybdenum: 4.8 × 10 ⁻⁶
Niobium: 8.0 × 10 ^-6
Titanium: 11 × 10 ⁻⁶

  It is preferable that the metal constituting the metal film 120 is not oxidized and there is almost no oxide film on the surface of the metal film 120. This is because even if a stress gradient is generated in the metal film 120, diffusion bonding does not occur sufficiently in the oxidized metal, which becomes a main cause of bonding failure. In order to avoid surface oxidation, heating for bonding may be performed in a reducing atmosphere or a vacuum atmosphere. Alternatively, the joining is preferably performed under conditions (temperature or atmosphere) that promote a redox reaction on the surface of the metal.

  Here, the stress migration of metal will be described with reference to FIG. FIG. 2 (a) is a view showing an SEM photograph after the silver film on the silicon surface is heated at 250 ° C. 2 (b) is a partially enlarged view of FIG. 2 (a), and FIG. 2 (c) is a view showing an SEM photograph of the cross section of FIG. 2 (b).

  2 (a), 2 (b), and 2 (c), when the stress migration of silver is manifested by heating, the surface of the silver film bulges up so as to overflow from the inside. It can be confirmed that it was formed. In the present embodiment, by using such metal stress migration, the raised metal (for example, silver) diffuses so as to rise from the surface, and the interface between the semiconductor element 110 and the metal film 120, the metal film 120. By filling the unevenness present at the interface between these layers or at the interface between the metal film 120 and the wiring 130, a good bonding state is realized.

  Here, with reference to FIG. 3, the manufacturing method of the joining structure 100 of this embodiment is demonstrated.

  First, as shown to Fig.3 (a), the laminated body L is prepared. In the stacked body L, the semiconductor element 110 and the wiring 130 are stacked via the metal film 120. For example, after the metal film 120 is formed on the semiconductor element 110, the stacked body L may be manufactured by bringing the wiring 130 into contact with the metal film 120. Alternatively, after forming the metal film 120 on the wiring 130, the stacked body L may be manufactured by bringing the semiconductor element 110 into contact with the metal film 120.

  The crystal state of the metal constituting the metal film 120 is preferably a fine crystal or a columnar crystal. In this case, the crystal state of the metal is preferably a fine crystal or a columnar crystal in at least a part of the surface of the wiring 130. For example, the metal film 120 is formed by sputtering, plating, or vapor deposition.

  Next, as illustrated in FIG. 3B, when the stacked body L is heated, the metal constituting the metal film 120 is diffused by stress migration, and the semiconductor element 110 and the wiring 130 are joined. The heating temperature of the laminate L is preferably 100 ° C. or higher and 400 ° C. or lower, and more preferably 150 ° C. or higher and 300 ° C. or lower.

  Heating may be performed at atmospheric pressure or in vacuum. Alternatively, the heating may be performed in an inert gas or reducing (eg, argon, nitrogen, hydrogen, or formic acid) atmosphere.

  In the case where the metal film 120 is made of a metal that easily oxidizes, an oxide film may be formed on the surface of the metal film 120. Since the metal may not be diffused well in the presence of the oxide film, the heating is preferably performed in a vacuum or while removing the oxide film. In order to remove the oxide film, for example, heating may be performed in an atmosphere of hydrogen or formic acid (gas). For example, when the metal constituting the metal film 120 is silver, the heating may be performed at atmospheric pressure. Or when the metal which comprises the metal film 120 is copper, it is preferable that a heating is performed in a vacuum.

  According to the present embodiment, since the semiconductor element 110 and the wiring 130 are bonded by utilizing metal diffusion due to stress migration, the bonding can be performed well even at a relatively low heating temperature of 400 ° C. or less. Therefore, damage to the semiconductor element 110 or the wiring 130 due to heat during heating, or generation of voids in the vicinity of the joint portion between the semiconductor element 110 and the wiring 130 can be suppressed. Moreover, since the manufacturing method of this embodiment uses metal diffusion due to stress migration, bonding can be performed at a relatively low pressure. For example, bonding can be performed with no pressure or a pressure of 1 MPa or less.

  Next, with reference to FIG. 4, the manufacturing method of the junction structure 100 of this embodiment is demonstrated. The method for manufacturing a bonded structure according to the present embodiment includes a metal film forming step, a laminate manufacturing step, and a bonding step.

(Metal film forming process)
As shown in FIG. 4A, a metal film 120 a is formed on the surface of the semiconductor element 110. The metal film 120a is formed, for example, by sputtering, plating, or vapor deposition. The method of the sputtering process is not particularly limited, and for example, RF (high frequency) sputtering and DC (direct current) sputtering can be employed. The plating method is not particularly limited, and for example, electrolytic plating or electroless plating can be employed. Alternatively, the deposition method is not particularly limited, and for example, vacuum deposition using resistance heating can be employed. Note that the metal film 120a may be formed of a plurality of metal layers.

  Further, as shown in FIG. 4B, a metal film 120b is formed on the surface of the wiring. Typically, the metal constituting the metal film 120b is the same as the metal constituting the metal film 120a, but the metal constituting the metal film 120b may be different from the metal constituting the metal film 120a. Similarly to the metal film 120a, the metal film 120b can be formed by sputtering, plating, or vapor deposition, for example. Note that the metal film 120b may be formed of a plurality of metal layers.

(Laminate production process)
Next, as illustrated in FIG. 4C, the semiconductor element 110 and the wiring 130 are stacked so that the metal film 120 a on the semiconductor element 110 and the metal film 120 b on the wiring 130 are in contact with each other, thereby forming the stacked body L. Make it. In this case, the stacked body L has a configuration in which the semiconductor element 110, the metal films 120a and 120b, and the wiring 130 are stacked.

(Joining process)
Next, as illustrated in FIG. 4D, the stacked body L is heated to bond the semiconductor element 110 and the wiring 130, thereby manufacturing the bonded structure 100. When the metal constituting the metal film 120a on the semiconductor element 110 and / or the metal constituting the metal film 120b on the wiring 130 are diffused by stress migration due to heating, between the interfaces of the metal film 120a and the metal film 120b. The space is filled, and the metal film 120 in which the metal film 120a and the metal film 120b are integrated is formed. As a result, the semiconductor element 110 and the wiring 130 are joined by the metal film 120.

  In the heated metal film 120, the interface between the two layers derived from the metal film 120a and the metal film 120b may or may not be clearly specified. The heating temperature of the laminate L is preferably 100 ° C. or higher and 400 ° C. or lower, and more preferably 150 ° C. or higher and 300 ° C. or lower.

  In the above description, the metal films 120, 120a, and 120b are formed directly on the semiconductor element 110 or the wiring 130, but the present invention is not limited to this. The metal films 120, 120a, 120b may be formed on the semiconductor element 110 or the wiring 130 via an adhesive layer.

  In FIG. 5, the schematic diagram of the joining structure 100 of this embodiment is shown. The bonded structure 100 includes adhesive layers 140 a and 140 b in addition to the semiconductor element 110, the metal film 120, and the wiring 130. The adhesive layer 140 a is located between the semiconductor element 110 and the metal film 120, and the adhesive layer 140 b is located between the metal film 120 and the wiring 130. The adhesion between the semiconductor element 110 and the metal film 120 and the adhesion between the metal film 120 and the wiring 130 can be strengthened by the adhesion layers 140a and 140b.

  The material constituting the adhesive layers 140a and 140b is, for example, titanium or titanium nitride. The thickness of the adhesive layers 140a and 140b is, for example, not less than 0.01 μm and not more than 0.05 μm.

  In the bonding structure 100 shown in FIG. 5, the adhesive layers 140a and 140b are provided on both sides of the metal film 120, but only one of the adhesive layer 140a or the adhesive layer 140b is provided on one side of the metal film 120. It may be provided. As described above, in the bonding structure 100, an adhesive layer may be formed between the semiconductor element 110 and the metal film 120 or between the metal film 120 and the wiring 130.

  In the above description, the mode in which one side of the semiconductor element 110 and the wiring 130 are bonded via the metal film 120 has been described, but the other side of the semiconductor element 110 may be bonded to the substrate.

  In FIG. 6, the schematic diagram of the joining structure 100 of this embodiment is shown. The bonded structure 100 of this embodiment includes a metal film 150 and a connection substrate 160 in addition to the semiconductor element 110, the metal film 120, and the wiring 130. The semiconductor element 110 and the connection substrate 160 are joined by a metal film 150.

  The metal film 120 is provided on one main surface of the semiconductor element 110, whereas the metal film 150 is provided on the other main surface of the semiconductor element 110. For example, the metal film 150 is made of any one of the metals constituting the metal film 120 described above. The metal constituting the metal film 150 may be the same as or different from the metal constituting the metal film 120.

  The connection substrate 160 includes an insulating substrate 160a, an electrode 160b, and an electrode 160c. The electrode 160b is provided on one main surface of the insulating substrate 160a, and the electrode 160c is provided on the other main surface of the insulating substrate 160a.

  The material constituting the insulating substrate 160a is, for example, glass, silica glass, silicon, silicon carbide, gallium nitride, gallium nitride formed on silicon, silicon nitride, or aluminum nitride. The material constituting the electrodes 160b and 160c is, for example, copper, iron, or silver. When the insulating substrate 160a is made of silicon nitride and the electrodes 160b and 160c are made of copper, the connection substrate 160 is also called a DCB (Direct Copper Bonding) substrate. In this case, the metal film 150 is in direct contact with the electrode 160b having a relatively high coefficient of thermal expansion, but is connected to the insulating substrate 160a having a relatively low coefficient of thermal expansion via the electrode 160b. And stress migration due to the difference in thermal expansion coefficient between the insulating substrate 160a and the insulating substrate 160a.

  In the above description, the two members to be joined are joined via the same metal film, but the present invention is not limited to this. In the above description, the semiconductor element which is an active element and the wiring are joined, but the present invention is not limited to this.

  Below, with reference to FIG. 7, the junction structure which concerns on another embodiment of this invention is demonstrated. FIG. 7 is a schematic diagram of the bonded structure 200 of the present embodiment.

  The bonded structure 200 includes a member 210, a metal film 220, a thermal stress absorber 230, a metal film 240, and a member 250. In the bonded structure 200, the member 210, the metal film 220, the thermal stress absorber 230, the metal film 240, and the member 250 are laminated in this order. In the following description of the present specification, the member 210 and the member 250 may be referred to as a first member 210 and a second member 250, respectively, and the metal film 220 and the metal film 240 are respectively referred to as a first metal. The film 220 and the second metal film 240 may be described.

  The first member 210 includes a metal member or an insulating member provided with a conduction portion. The first member 210 is a passive element not provided with an active element such as a semiconductor. The first metal film 220 is bonded to the first member 210 and the thermal stress absorber 230.

  The second member 250 includes a metal member or an insulating member provided with a conduction portion. The second member 250 is a passive element not provided with an active element such as a semiconductor. The second metal film 240 is bonded to the thermal stress absorber 230 and the second member 250.

  In the bonded structure 200, the first member 210 and the second member 250 are bonded via the first metal film 220, the thermal stress absorber 230, and the second metal film 240. In the bonded structure 200 of the present embodiment, the metal constituting the first metal film 220 is diffused by stress migration, and the metal constituting the second metal film 240 is diffused by stress migration.

  Hereinafter, the first member 210, the first metal film 220, the thermal stress absorbing material 230, the second metal film 240, and the second member 250 in the bonded structure 200 will be described.

(First member 210)
When the first member 210 includes an insulating member, the first member 210 preferably includes an insulating material as a main component, and typically, the first member 210 is preferably formed of an insulating member. However, the conduction part of the insulating member is in contact with the first metal film 220. In addition, the material of the insulating member which comprises the 1st member 210 is glass, silica glass, silicon | silicone, carbon, or ceramics, for example.

  When the first member 210 includes a metal member, the first member 210 preferably includes a metal material as a main component, and typically, the first member 210 is configured from a metal member. preferable. The material of the metal member constituting the first member 210 is, for example, copper, silver, zinc, gold, palladium, aluminum, nickel, cobalt, iron, alumina, tungsten, niobium, molybdenum, titanium, stainless steel, ion bar alloy ( An alloy containing iron, nickel, manganese and carbon as constituents) or a kovar alloy (an alloy containing iron, nickel, cobalt, manganese and silicon as constituents).

(First metal film 220)
The metal constituting the first metal film 220 is, for example, copper, silver, zinc, gold, palladium, aluminum, nickel, cobalt, or iron. The metal constituting the first metal film 220 is copper, silver, zinc, aluminum, cobalt, or nickel in order to have a thermal expansion coefficient that is excellent in versatility and cost performance and can easily generate stress migration. Is preferred.

  The first metal film 220 may be composed of a plurality of stacked metal layers. When the first metal film 220 has a laminated structure, each of the metals constituting the plurality of metal layers may be the same type of metal or a different type of metal. The metal diffused by the stress migration is an interface between the first member 210 and the first metal film 220, an interface between the first metal film 220 and the thermal stress absorber 230, or an interface between layers in the first metal film 220. Move to fill the unevenness.

  The thickness of the first metal film 220 is preferably 0.5 μm or more and 30.0 μm or less in order to have excellent bonding strength and easily generate stress migration.

The thermal expansion coefficient (linear expansion coefficient) of the metal constituting the first metal film 220 is preferably higher than the thermal expansion coefficient (linear expansion coefficient) of the material constituting the first member 210. For example, the coefficient of thermal expansion of the metal constituting the first metal film 220 is 10.0 × 10 ⁻⁶ or more, and the coefficient of thermal expansion of the material constituting the first member 210 is 0.1 × 10 ⁻⁶ or more. It is less than 0 × 10 ⁻⁶ .

  In particular, the ratio of the thermal expansion coefficient of the metal constituting the first metal film 220 to the thermal expansion coefficient of the material constituting the first member 210 (the thermal expansion coefficient of the metal constituting the first metal film 220 / the first member 210). The thermal expansion coefficient of the constituent material is preferably 2.0 or more. However, the coefficient of thermal expansion of the metal constituting the first metal film 220 is not necessarily higher than the coefficient of thermal expansion of the material constituting the first member 210, and the first member 210 is compared with the coefficient of thermal expansion. It may be made of a high-quality material.

  The crystal state of the metal constituting the first metal film 220 is preferably a fine crystal or a columnar crystal. When the crystal state is a columnar crystal, the metal constituting the first metal film 220 diffuses along the surface or the grain boundary, so that stress is more easily compared with a metal having a coarse equiaxed crystal state. Since migration can be generated, the bonding state is improved.

  In the joint structure 200, a suitable combination of the material constituting the first member 210 and the metal constituting the first metal film 220 (first member 210 / first metal film 220) effectively generates stress migration. For example, silicon / silver, carbon / silver, molybdenum / silver, tungsten / silver, stainless steel / silver, silicon / copper, carbon / copper, molybdenum / copper, or tungsten / Copper.

(Second metal film 240)
The metal constituting the second metal film 240 is, for example, copper, silver, zinc, gold, palladium, aluminum, nickel, cobalt, or iron. Copper, silver, zinc, aluminum, cobalt, or nickel is preferable because it has excellent versatility and cost performance and has a coefficient of thermal expansion that can easily generate stress migration.

  The second metal film 240 may be composed of a plurality of stacked metal layers. When the second metal film 240 has a laminated structure, each of the metals constituting the plurality of metal layers may be the same type of metal or a different type of metal. The metal diffused by the stress migration is an interface between the thermal stress absorber 230 and the second metal film 240, an interface between the second metal film 240 and the second member 250, or an interface between layers in the second metal film 240. Move to fill the unevenness.

  The thickness of the second metal film 240 is preferably 0.5 μm or more and 30.0 μm or less in order to have excellent bonding strength and easily generate stress migration.

  The crystal state of the metal constituting the second metal film 240 is preferably a fine crystal or a columnar crystal. When the crystal state is a columnar crystal, the metal constituting the second metal film 240 diffuses along the surface or the crystal grain boundary. Therefore, stress is more easily compared with a metal whose crystal state is a coarse equiaxed crystal. Since migration can be generated, the bonding state is improved.

(Second member 250)
Examples of the material constituting the second member 250 include those exemplified above as the material constituting the first member 210.

The thermal expansion coefficient (linear expansion coefficient) of the material forming the second member 250 is higher than the thermal expansion coefficient (linear expansion coefficient) of the metal forming the second metal film 240 in order to improve the bonding by stress migration. Preferably it is low. For example, the thermal expansion coefficient of the material constituting the second member 250 is 0.1 × 10 ⁻⁶ or more and less than 10.0 × 10 ⁻⁶ , and the thermal expansion coefficient of the metal constituting the second metal film 240 is 10.4. It is 0 × 10 ⁻⁶ or more.

  In particular, the ratio of the thermal expansion coefficient of the material constituting the second metal film 240 to the thermal expansion coefficient of the material constituting the second member 250 (the thermal expansion coefficient of the metal constituting the second metal film 240 / the second member 250). The thermal expansion coefficient of the constituent material is preferably 2.0 or more. However, the thermal expansion coefficient (linear expansion coefficient) of the material constituting the second member 250 is not necessarily lower than the thermal expansion coefficient (linear expansion coefficient) of the metal forming the second metal film 240. The second member 250 may be made of a material having a relatively high coefficient of thermal expansion.

  In the bonded structure 200, a suitable combination of the metal constituting the second metal film 240 and the material constituting the second member 250 (second metal film 240 / second member 250) effectively generates stress migration. For example, silver / silicon, silver / carbon, silver / molybdenum, silver / tungsten, silver / stainless steel, copper / silicon, copper / carbon, copper / molybdenum, or copper / Tungsten.

(Thermal stress absorber 230)
By providing the thermal stress absorbing material 230, it is possible to suppress thermal shock during heating and to develop good stress migration. Examples of the material constituting the thermal stress absorber 230 include the same materials as those constituting the first member 210 or the second member 250. In order to develop good stress migration, the material constituting the thermal stress absorber 230 is molybdenum, tungsten, niobium, titanium, silicon, carbon, graphite, silicon carbide, silicon nitride, aluminum nitride, alumina, or invar. An alloy may be used.

The thermal expansion coefficient (linear expansion coefficient) of the material constituting the thermal stress absorbing material 230 is such that the thermal expansion coefficient of the metal forming the first and second metal films 220 and 240 ( It is preferable that it is lower than the linear expansion coefficient. For example, the coefficient of thermal expansion of the material constituting the thermal stress absorbing material 230 is 0.1 × 10 ⁻⁶ or more and less than 10.0 × 10 ⁻⁶ , and the metal constituting the first and second metal films 220 and 240 is formed. The coefficient of thermal expansion is 10.0 × 10 ⁻⁶ or more. In particular, the ratio of the thermal expansion coefficient of the material constituting the first and second metal films 220 and 240 to the thermal expansion coefficient of the material constituting the thermal stress absorbing material 230 (the first and second metal films 220 and 240 are constituted. The thermal expansion coefficient of the metal / the thermal expansion coefficient of the material constituting the thermal stress absorber 230 is preferably 2.0 or more.

  In addition, it is preferable that at least a part of the surface of the thermal stress absorber 230 is covered with a metal film. By doing so, stress migration can be expressed more effectively and good bonding can be performed. Examples of the metal constituting the metal film for covering the surface of the thermal stress absorber 230 include the same metal as the metal constituting the first metal film 220 or the metal constituting the second metal film 240. .

  The bonded structure 200 of the present embodiment realizes good bonding by using stress migration. Specifically, when the temperature is changed while two kinds of materials having a large difference in thermal expansion coefficient are in contact with each other, a stress gradient is generated in the metal film 220. This gradient causes stress migration, and the metal of the metal films 220 and 240 diffuses so as to overflow from the surface. When the metal of the metal film 220 diffuses, the metal is an uneven gap at the interface between the first member 210 and the metal film 220, the interface between the metal film 220 and the thermal stress absorber 230, or the interface inside the metal film 220. The first member 210 and the thermal stress absorbing material 230 are well bonded by the metal film 220. Further, when the metal of the metal film 240 is diffused, the metal is uneven at the interface between the thermal stress absorber 230 and the metal film 240, the interface between the metal film 240 and the second member 250, or the interface inside the metal film 240. The thermal stress absorbing material 230 and the second member 250 are satisfactorily bonded by the metal film 220.

  In the present embodiment, the first member 210 and the second member 250 are joined using stress migration of the metal constituting the metal films 220 and 240. Since stress migration occurs at a temperature lower than a general sintering temperature, the bonding structure 200 of the present embodiment can realize good bonding even in a low temperature environment. Moreover, even when the heat resistance of either the first member 210 or the second member 250 is low, the first member 210 and the second member 250 can be satisfactorily joined. In addition, since a large-scale apparatus such as a heating furnace is not required, bonding can be performed at a low cost with a simple process. Furthermore, bonding can be performed using inexpensive and versatile metals such as copper. Furthermore, regardless of the size of the first member 210 and the second member 250, the first member 210 and the second member 250 can be connected well.

  Further, as described above with reference to FIG. 5, also in the bonded structure 200, between the first member 210 and the first metal film 220 and between the first metal film 220 and the thermal stress absorber 230. In addition, an adhesive layer may be formed between the thermal stress absorber 230 and the second metal film 240 and / or between the second metal film 240 and the second member 250. By the adhesive layer, adhesion between the first member 210 and the first metal film 220, adhesion between the first metal film 220 and the thermal stress absorber 230, and between the thermal stress absorber 230 and the second metal film 240 are achieved. Adhesion between and / or adhesion between the second metal film 240 and the second member 250 can be strengthened. The material constituting the adhesive layer is, for example, titanium or titanium nitride. The thickness of the adhesive layer is, for example, not less than 0.01 μm and not more than 0.05 μm.

  Here, with reference to FIG. 8, the manufacturing method of the joining structure 200 of this embodiment is demonstrated. The manufacturing method of the bonded structure 200 of the present embodiment includes a metal film forming step, a laminate manufacturing step, and a bonding step.

(Metal film forming process)
As shown in FIG. 8A, a metal film 220a is formed on the surface of the first member 210. For example, the metal film 220a is formed by sputtering, plating, or vapor deposition. The method of the sputtering process is not particularly limited, and for example, RF (high frequency) sputtering and DC (direct current) sputtering can be employed. The plating method is not particularly limited, and for example, electrolytic plating or electroless plating can be employed. Alternatively, the deposition method is not particularly limited, and for example, vacuum deposition using resistance heating can be employed. Note that the metal film 220a may be formed of a plurality of metal layers.

  As shown in FIG. 8B, a metal film 240 a is formed on the surface of the second member 250. The metal film 240a can be formed by a method similar to that for the metal film 220a. Note that the metal film 240a may be formed of a plurality of metal layers.

  As shown in FIG. 8C, metal films 220 b and 240 b are formed on both surfaces of the thermal stress absorber 230. The metal films 220b and 240b can be formed in the same manner as the metal film 220a. The metal films 220b and 240b may be formed from a plurality of metal layers.

(Laminate production process)
As shown in FIG. 8D, the thermal stress absorber 230 is laminated on the first member 210 so that the metal film 220a on the first member 210 is in contact with the metal film 220b on the thermal stress absorber 230. The first member 210 is laminated on the thermal stress absorber 230 such that the metal film 240b on the thermal stress absorber 230 is in contact with the metal film 240a on the second member 250. As described above, the stacked body L in which the first member 210, the metal films 220a and 220b, the thermal stress absorber 230, the metal films 240b and 240a, and the second member 250 are stacked is manufactured.

(Joining process)
Next, as illustrated in FIG. 8E, the stacked body L is heated to join the first member 210 and the second member 250 with the metal film 220, the thermal stress absorber 230, and the metal film 240. The structure 200 is produced. When the stacked body L is heated, the metal constituting the metal film 220a on the first member 210, the metal films 220b and 240b on the thermal stress absorber 230, and / or the metal constituting the metal film 240a on the second member 250 are formed. It spreads by stress migration. Thereby, a space between the interface between the metal film 220a and the metal film 220b and / or between the interface between the metal film 240a and the metal film 240b is filled, and the metal film 220 in which the metal film 220a and the metal film 220b are integrated. And / or the metal film 240 with which the metal film 240a and the metal film 240b were integrated is formed, and the 1st member 210 and the 2nd member 250 are joined.

  In the metal film 220, the interface between the two layers derived from the metal film 220a and the metal film 220b may or may not be clearly specified. Similarly, in the metal film 240, the interface between the two layers derived from the metal film 240a and the metal film 240b may be clearly specified or may not be specified.

  The heating temperature of the laminate L is preferably 100 ° C. or higher and 400 ° C. or lower, and more preferably 150 ° C. or higher and 300 ° C. or lower. Heating may be performed under atmospheric pressure or in a vacuum. Alternatively, the heating may be performed in an inert gas or reducing (eg, argon, nitrogen, hydrogen, or formic acid) atmosphere.

  Since the manufacturing method of this embodiment uses metal diffusion due to stress migration, bonding can be performed at a relatively low pressure. For example, bonding can be performed with no pressure or a pressure of 1 MPa or less.

  As shown in FIG. 8C, when the metal films 220b and 240b are formed on both surfaces of the thermal stress absorber 230, the metal films 220b and 240b are simultaneously formed on both surfaces of the thermal stress absorber 230. Is preferred. The formation of the metal films 220b and 240b may be performed under heating conditions. However, when the metal films 220b and 240b are formed in order, the adhesive strength due to the previously formed metal film may be reduced. It is.

  In the above description with reference to FIG. 8, the metal film 220 a is formed on the first member 210, the metal film 220 b is formed on the thermal stress absorber 230, and then the metal film 220 a and the metal film 220 b are made of metal. Although the film 220 is formed, the present invention is not limited to this. Only one of the metal film 220a and the metal film 220b may be formed, and the first member 210 and the thermal stress absorbing material 230 may be bonded by the formed metal film.

  Similarly, in the above description with reference to FIG. 8, the metal film 240 a is formed on the second member 250, the metal film 240 b is formed on the thermal stress absorber 230, and then the metal film 240 a and the metal film 240 b are used. Although the metal film 240 is formed, the present invention is not limited to this. Only one of the metal film 240a and the metal film 240b may be formed, and the thermal stress absorbing material 230 and the second member 250 may be bonded by the formed metal film.

  The thermal stress absorber 230 is preferably provided with a through hole or a depression. In this case, the metal is introduced into the through hole or the depression of the thermal stress absorber 230, and the stress gradient between the metal and the thermal stress absorber 230 can be made more remarkable. As a result, the metal diffuses so as to overflow from the through-hole or the depression, and stress migration can be expressed more effectively to achieve a good bonded state.

  9 to 11 are schematic views of the thermal stress absorber 230, respectively. FIG. 9 shows one form of the thermal stress absorber 230. The thermal stress absorbing material 230 shown in FIG. 9 has a rectangular parallelepiped shape, and the thermal stress absorbing material 230 has a through-hole 260 penetrating from one flat main surface to the other flat main surface. Arranged at intervals. For example, the through holes 260 having a diameter of about 0.2 mm are arranged at equal intervals of about 5 mm. Although not shown here, the through holes 260 may be provided in the thermal stress absorber 230 at random.

  FIG. 10 shows another form of the thermal stress absorbing material 230. In the thermal stress absorbing material 230 shown in FIG. 10, a plurality of grooves 270 are arranged in parallel at equal intervals as depressions on each of the two main surfaces. In addition, although not shown here, the recess may have a shape depressed in a circular shape.

  FIG. 11 shows still another form of the thermal stress absorbing material 230. The thermal stress absorbing material 230 shown in FIG. 11 has a rectangular parallelepiped shape, and the through holes 260 are formed by annular members 280 arranged at equal intervals. Although not shown here, the annular members may be arranged at random.

  In the bonded structure 200 described above with reference to FIGS. 7 and 8, the first member 210 and the second member 250 are bonded via the metal film 220, the thermal stress absorber 230, and the metal film 240. The present invention is not limited to this. The first member and the second member may be joined without interposing a thermal stress absorber.

  With reference to FIG. 12, an embodiment of a bonded structure according to the present invention will be described. FIG. 12 is a schematic diagram of the bonded structure 100A of the present embodiment. The bonded structure 100A includes a member 110A, a metal film 120, and a member 130A. The member 110A includes a metal member or an insulating member provided with a conduction portion. The member 130A includes a metal member or an insulating member provided with a conduction portion. In the following description of the present specification, the member 110A and the member 130A may be referred to as a first member 110A and a second member 130A, respectively.

  The metal film 120 joins the first member 110A and the second member 130A. In the bonded structure 100A, the first member 110A, the metal film 120, and the second member 130A are stacked in this order.

  In the bonded structure 100A of the present embodiment, the metal constituting the metal film 120 is diffused by stress migration, so that the first member 110A and the second member 130A are bonded via the metal film 120. Specifically, a stress gradient is generated inside the metal film 120, and the metal constituting the metal film 120 is diffused to maintain the bonded state. Stress migration occurs at any of the interface between the first member 110A and the metal film 120, the interface between the metal film 120 and the second member 130A, and the inside of the metal film 120.

  Hereinafter, the first member 110A, the metal film 120, and the second member 130A constituting the bonded structure 100A will be described.

(First member 110A)
When 110 A of 1st members contain an insulating member, it is preferable that 110 A of 1st members have an insulating material as a main component, and it is preferable that 110 A of 1st members are typically comprised from an insulating member. However, this insulating member is provided with a conducting portion, and the first metal film 220 is in contact with the conducting portion. The material of the insulating member constituting the first member 110A is, for example, glass, silica glass, silicon, or ceramics.

  In addition, when the first member 110A includes a metal member, the first member 110A preferably includes a metal material as a main component. Typically, the first member 110A is formed of a metal member. preferable. The material of the metal member constituting the first member 110A is, for example, copper, silver, zinc, gold, palladium, aluminum, nickel, cobalt, iron, alumina, tungsten, niobium, molybdenum, titanium, stainless steel, ion bar alloy ( An alloy containing iron, nickel, manganese and carbon as constituents) or a kovar alloy (an alloy containing iron, nickel, cobalt, manganese and silicon as constituents).

(Metal film 120)
The metal constituting the metal film 120 is, for example, copper, silver, zinc, gold, palladium, aluminum, nickel, cobalt, or iron. The metal constituting the metal film 120 is preferably copper, silver, zinc, aluminum, cobalt, or nickel in order to have a thermal expansion coefficient that is excellent in versatility and cost performance and can easily generate stress migration.

  The metal film 120 may have a configuration in which a plurality of metal layers are stacked. When the metal film 120 has a laminated structure, the metals constituting the plurality of metal layers may be the same type of metal or different types of metals. Further, in this case, the metal diffused by stress migration is uneven at the interface between the first member 110A and the metal film 120, the interface between the metal films 120, or the interface between the metal film 120 and the second member 130A. Move to fill.

  The thickness of the metal film 120 is preferably 0.5 μm or more and 30.0 μm or less in order to have excellent bonding strength and easily generate stress migration.

The coefficient of thermal expansion (linear expansion coefficient) of the metal constituting the metal film 120 is preferably higher than the coefficient of thermal expansion (linear expansion coefficient) of the material constituting the first member 110A. In particular, the ratio of the thermal expansion coefficient of the metal constituting the metal film 120 to the thermal expansion coefficient of the material constituting the first member 110A (the thermal expansion coefficient of the metal constituting the metal film 120 / the material constituting the first member 110A). The coefficient of thermal expansion is preferably 2.0 or more. For example, the thermal expansion coefficient of the metal constituting the metal film 120 is 10.0 × 10 ⁻⁶ or more, and the thermal expansion coefficient of the material constituting the first member 110A is, for example, 0.1 × 10 ⁻⁶ or more. It is less than 10.0 × 10 ⁻⁶ .

  Note that, as described above with respect to the bonded structure 200 with reference to FIG. 5, also in the bonded structure 100A, between the first member 110A and the metal film 120 and / or the second member 130A and the metal film. An adhesive layer may be formed between 120 and 120. The adhesive layer is formed for the purpose of strengthening the adhesion between the first member 110A and the metal film 120 and / or the adhesion between the metal film 120 and the second member 130A. The material constituting the adhesive layer is, for example, titanium or titanium nitride. The thickness of the adhesive layer is, for example, not less than 0.01 μm and not more than 0.05 μm.

  Below, with reference to FIG. 13, the manufacturing method of 100 A of joining structures of this embodiment is demonstrated. The manufacturing method of the bonded structure 100A of the present embodiment includes a metal film forming process, a laminate manufacturing process, and a bonding process.

(Metal film forming process)
As shown in FIG. 13A, a metal film 120a is formed on the surface of the first member 110A. The metal film 120a is formed, for example, by sputtering, plating, or vapor deposition. The method of the sputtering process is not particularly limited, and for example, RF (high frequency) sputtering and DC (direct current) sputtering can be employed. The plating method is not particularly limited, and for example, electrolytic plating or electroless plating can be employed. Alternatively, the deposition method is not particularly limited, and for example, vacuum deposition using resistance heating can be employed. Note that the metal film 120a may be formed of a plurality of metal layers.

  Further, as shown in FIG. 13B, a metal film 120b is formed on the surface of the second member 130A. Typically, the metal constituting the metal film 120b is the same as the metal constituting the metal film 120a, but the metal constituting the metal film 120b may be different from the metal constituting the metal film 120a. For the formation of the metal film 120b, a technique such as sputtering, plating, or vapor deposition can be used as in the case of the metal film 120a. Note that the metal film 120b may be formed of a plurality of metal layers.

(Laminate production process)
Next, as shown in FIG. 13C, the first member 110A and the second member 130A are laminated so that the metal film 120a on the first member 110A and the metal film 120b on the second member 130A are in contact with each other. Thus, the laminate L is manufactured. In this case, the stacked body L has a configuration in which the first member 110A, the metal films 120a and 120b, and the second member 130A are stacked.

(Joining process)
Next, as illustrated in FIG. 13D, by heating the stacked body L, a bonded structure 100 </ b> A in which the first member 110 </ b> A and the second member 130 </ b> A are bonded by the metal film 120 is manufactured. When the stacked body L is heated, the metal constituting the metal film 120a on the first member 110A and / or the metal constituting the metal film 120b on the second member 130A are diffused by stress migration, and the metal film 120a and the metal film 120b are diffused. The first member 110A and the second member 130A are joined by filling the space between the first member 110A and the second member 130 with a metal.

  In the metal film 120, the interface between the two layers derived from the metal film 120a and the metal film 120b may or may not be clearly specified. The heating temperature of the laminate L is preferably 100 ° C. or higher and 400 ° C. or lower, and more preferably 150 ° C. or higher and 300 ° C. or lower.

  Although details are currently under consideration, when the surface of the metal film is raised by stress migration, nanoparticles are observed to promote the formation of necking between particles in the vicinity of the raised portion.

  14A is a diagram showing a cross section of a silver film in which stress migration has occurred, FIG. 14B is an enlarged view of region B in FIG. 14A, and FIG. It is a schematic diagram for demonstrating the stress migration.

  As is apparent from FIGS. 14A and 14B, when the surface of the silver film is raised by stress migration, nanoparticles are formed in the vicinity of the raised portion. In addition, it is thought that the outermost layer of the silver film indicated by arrow D in FIG. 14B is an oxide layer, and the reduction reaction proceeds by the oxide layer to promote sintering.

  At present, as shown in FIG. 14C, nano-sized particles are moving from the inside of the silver film along the oxide layer toward the normal direction of the surface, and these nano-sized particles are subjected to stress migration. It seems to be closely related to

  FIG. 15 is a schematic diagram for explaining joining by metal stress migration. As shown in FIG. 15, immediately after the start of bonding, the metal swells in a granular form so as to overflow from the inside of each of the two metal films and comes into contact with each other to form a bonding necking. Since the energy of the contact area is relatively high, the metal nanoparticles move from the inside of each of the two metal films toward the contact area, filling the junction necking depression, and as a result, the raised area is It expands in the horizontal direction, and it is thought that two metal films are finally bonded.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the examples.

Example 1
Below, with reference to FIG. 16, the junction structure 100 of Example 1 is demonstrated. FIG. 16A is a schematic cross-sectional view of the bonded structure 100 of the first embodiment. FIG. 16B is a perspective view showing the joint structure 100 according to the first embodiment.

  The bonding structure 100 of Example 1 was provided with the semiconductor element 110, the metal film 120, the wiring 130, the adhesive layers 140a to 140c, the metal film 150, and the connection substrate 160. The joined structure 100 of Example 1 was produced as follows.

(Metal film forming process)
A SiC chip was prepared as the semiconductor element 110. On one main surface of the SiC chip, a titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 140a by sputtering. A silver film having a thickness of about 1 μm was formed as a metal film 120a on the surface of the titanium layer.

  Further, a titanium layer having a thickness of about 0.04 μm was formed as the adhesive layer 140c on the other main surface of the SiC chip by a sputtering process. A silver film having a thickness of about 1 μm was formed as a metal film 150a on the surface of the titanium layer by sputtering.

  A Cu wire as the wiring 130 was prepared. On the surface of one end of the Cu wire, a titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 140b by sputtering. On the surface of the titanium layer, a silver film having a thickness of about 1 μm was formed as a metal film 120b by sputtering.

  A silicon nitride substrate having a copper film formed on the surface was prepared as the connection substrate 160. A copper film having a thickness of about 0.1 μm as the electrodes 160b and 160c was formed on both surfaces of the silicon nitride substrate as the insulating substrate 160a by sputtering. Thereafter, a silver film having a thickness of about 1 μm was formed as a metal film 150b on the copper film by a sputtering process.

(Laminate production process)
Subsequently, one silver film of the SiC chip is disposed so as to be in contact with the silver film on the silicon nitride substrate, and the silver film of the Cu wire is disposed so as to be in contact with the other silver film of the SiC chip. Produced. Thereafter, the produced laminate was fixed with a clip so as not to move.

(Joining process)
The laminate was heated at 250 ° C. for 60 minutes in an atmospheric pressure atmosphere. The joined structure 100 of Example 1 was manufactured by heating. It was confirmed that the bonded structure 100 was bonded well.

(Example 2)
Below, with reference to FIG. 17, the joining structure 200 of Example 2 is demonstrated. FIG. 17A is a schematic diagram for explaining the configuration of the joint structure 200 of Example 2, and FIG. 17B is a diagram showing an SEM photograph in which the region B of FIG. 17A is enlarged. FIG. 17C is a diagram showing an SEM photograph in which the region C in FIG. 17A is enlarged.

  The joint structure 200 of Example 2 was provided with a member 210, a metal film 220, a thermal stress absorber 230, a metal film 240, adhesive layers 242a to 242d, and a member 250. The joined structure 200 of Example 2 was produced as follows.

(Metal film forming process)
A stainless steel (SUS316) substrate was prepared as the member 210. A titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 242c on one main surface of the stainless steel by a sputtering process. On the surface of this titanium layer, a silver film having a thickness of about 1 μm was formed as a metal film 220a by plating. FIG. 17B shows stainless steel on which a silver film has been formed by plating.

  Mounted stainless steel (SUS316) was prepared as the member 250. A titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 242d on one main surface of the mounted stainless steel by a sputtering process. On the surface of this titanium layer, a silver film having a thickness of about 1 μm was formed as a metal film 240a by plating.

  A molybdenum material was prepared as the thermal stress absorbing material 230. A titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 242a on one main surface of the molybdenum material by a sputtering process. A silver film having a thickness of about 1 μm was formed as a metal film 220b on the surface of the titanium layer by a sputtering process. FIG. 17C shows a molybdenum material on which a silver film is formed by a sputtering process.

  Further, a titanium layer having a thickness of about 0.04 μm was formed as the adhesive layer 242b on the other main surface of the molybdenum material by a sputtering process. On the surface of the titanium layer, a silver film having a thickness of about 1 μm was formed as a metal film 240b by a sputtering process.

(Laminate production process)
Subsequently, the molybdenum material is laminated on the stainless steel substrate so that the silver film on the stainless steel substrate is in contact with one silver film on the molybdenum material, and the other silver film on the molybdenum material is on the mounted stainless steel. Mounted stainless steel was laminated on the molybdenum material so as to be in contact with the silver film. A weight of 20 kg was placed on the mounted stainless steel so that the laminated body thus laminated did not move.

(Joining process)
While the weight was placed, the laminate was heated at 300 ° C. for 60 minutes in an atmospheric pressure atmosphere. The joined structure 200 of Example 2 was manufactured by heating. It was confirmed that the bonded structure 200 was bonded well.

(Example 3)
Below, with reference to FIG. 18, the joining structure 200 of Example 3 is demonstrated. 18A is a schematic diagram of the bonding structure 200 of Example 3, FIG. 18B is a diagram showing an SEM photograph of region B in FIG. 18A, and FIG. 18C is a diagram. FIG. 18B is a partially enlarged view of FIG.

  The joint structure 200 of Example 3 was provided with a member 210, a metal film 220, a thermal stress absorber 230, a metal film 240, adhesive layers 242c and 242d, and a member 250. The joined structure 200 of Example 3 was produced as follows.

(Metal film forming process)
A stainless steel (SUS316) substrate was prepared as the member 210. A titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 242c on one main surface of the stainless steel substrate by a sputtering process. On the surface of this titanium layer, a silver film having a thickness of about 1 μm was formed as a metal film 220a by plating.

  Mounted stainless steel (SUS316) was prepared as the member 250. A titanium layer having a thickness of about 0.04 μm was formed as a bonding layer 242d on one main surface of the mounted stainless steel by a sputtering process. On the surface of this titanium layer, a silver film having a thickness of about 1 μm was formed as a metal film 240a by plating.

  A titanium material was prepared as the thermal stress absorbing material 230. On one main surface of the titanium material, a silver film having a thickness of about 1 μm was formed as a metal film 220b by a sputtering process. A silver film having a thickness of about 1 μm was formed as a metal film 240b on the other main surface of the titanium material by a sputtering process.

(Laminate production process)
Subsequently, the titanium material is laminated on the stainless steel substrate so that the silver film on the stainless steel substrate is in contact with one silver film on the titanium material, and the other silver film on the titanium material is on the mounted stainless steel. Mounted stainless steel was laminated on the titanium material so as to be in contact with the silver film. A weight of 20 kg was placed on the mounted stainless steel so that the laminate thus produced would not move.

(Joining process)
While the weight was placed, the laminate was heated at 300 ° C. for 60 minutes in an atmospheric pressure atmosphere. The joined structure 200 of Example 3 was manufactured by heating. FIG. 18B shows a SEM photograph of the manufactured bonded structure 200, and FIG. 18C shows a partially enlarged view of FIG. 18B. It was confirmed that the bonded structure 200 was bonded well.

  The embodiments and examples of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiments and examples, and can be implemented in various modes without departing from the gist thereof. In addition, for ease of understanding, the drawings schematically show each component mainly as necessary, and the thickness, length, number, etc. of each component shown in the drawings are prepared. It may be different from the actual point of view. Moreover, the shape, dimension, etc. of each component shown by said embodiment and an Example are examples, Comprising: It cannot be overemphasized that various changes are possible without being specifically limited.

  The joint structure according to the present invention is suitably used for realizing a configuration in which a plurality of members are integrated.

DESCRIPTION OF SYMBOLS 100 Junction structure 110 Semiconductor element 120 Metal film 120a Metal film 120b Metal film 130 Wiring 100A Joining structure 110 1st member 120 Metal film 130 2nd member 140a Adhesion layer 140b Adhesion layer 150 Metal film 160 Connection board 200 Joining structure 210 First member 220 First metal film 230 Thermal stress absorber 240 Second metal film 250 Second member 260 Through-hole 270 Groove 280 Annular member

Claims (15)

A semiconductor element;
Wiring and
A metal film that joins the semiconductor element and the wiring ;
A bonding structure comprising: an adhesive layer provided between at least one of the semiconductor element and the metal film and between the wiring and the metal film ;
A joining structure in which the metal constituting the metal film is diffused by stress migration.   The bonding structure according to claim 1, wherein a coefficient of thermal expansion of a material constituting the semiconductor element and / or a material constituting the wiring is lower than a coefficient of thermal expansion of a metal constituting the metal film. A first member including a metal member or an insulating member;
A second member including a metal member or an insulating member;
A metal film that joins the first member and the second member ;
A bonding structure comprising: an adhesive layer provided between at least one of the first member and the metal film and between the second member and the metal film ;
The metal constituting the metal film is diffused by stress migration ,
A bonded structure except that the combination of the first member and the second member is a combination of a substrate and a semiconductor element .   The joining structure according to claim 3, wherein a coefficient of thermal expansion of a material constituting the first member and / or a material constituting the second member is lower than a coefficient of thermal expansion of a metal constituting the metal film. The metal film has a laminated structure in which a plurality of metal layers are laminated,
The joined structure according to any one of claims 1 to 4, wherein the plurality of metal layers are made of the same metal.   The bonded structure according to any one of claims 1 to 5, wherein a crystal state of a metal constituting the metal film is a fine crystal or a columnar crystal. A first member including a metal member or an insulating member;
A thermal stress absorber;
A second member including a metal member or an insulating member;
A first metal film that bonds the first member and the thermal stress absorber;
A bonded structure comprising a second metal film that bonds the thermal stress absorbing material and the second member,
At least one of the metal constituting the first metal film and the metal constituting the second metal film is diffused by stress migration ,
A bonded structure except that the combination of the first member and the second member is a combination of a substrate and a semiconductor element .   The thermal expansion coefficient of the material constituting the thermal stress absorber is lower than the thermal expansion coefficient of the metal constituting the first metal film and the thermal expansion coefficient of the metal constituting the second metal film. The joint structure according to the description. At least one of the first metal film and the second metal film has a stacked structure in which a plurality of metal layers are stacked,
The joined structure according to claim 7 or 8, wherein the plurality of metal layers are made of the same metal.   The bonded structure according to any one of claims 7 to 9, wherein a crystal state of a metal constituting the first metal film and / or a metal constituting the second metal film is a fine crystal or a columnar crystal.   The joint structure according to any one of claims 7 to 10, wherein a through hole or a depression is provided in the thermal stress absorbing material. Preparing a laminate in which a semiconductor element and a wiring are laminated via a metal film;
Heating the laminated body, diffusing the metal constituting the metal film by stress migration, and joining the semiconductor element and the wiring ,
In the step of preparing the stacked body, the stacked body is provided with an adhesive layer between at least one of the semiconductor element and the metal film and between the wiring and the metal film. The manufacturing method of a joining structure. Preparing a laminate in which a first member including a metal member or an insulating member and a second member including a metal member or an insulating member are stacked via a metal film;
Heating the laminated body, diffusing the metal constituting the metal film by stress migration, and joining the first member and the second member ,
In the step of preparing the laminated body, the laminated body is provided with an adhesive layer between at least one of the first member and the metal film and between the second member and the metal film. And
The method for manufacturing a bonded structure , except that the combination of the first member and the second member is a combination of a substrate and a semiconductor element . A first member including a metal member or an insulating member, a thermal stress absorber, a second member including a metal member or an insulating member, and a first metal film positioned between the first member and the thermal stress absorber And preparing a laminate in which a second metal film located between the thermal stress absorber and the second member is laminated,
Heating at least one of the first metal film and the second metal film, diffusing the metal constituting the first metal film and / or the second metal film by stress migration, and the first member and / or Or including a joining step of joining the second member and the thermal stress absorbing material ,
The method for manufacturing a bonded structure , except that the combination of the first member and the second member is a combination of a substrate and a semiconductor element .   The method for manufacturing a joined structure according to claim 12, wherein the joining step includes a step of heating to a temperature of 100 ° C. or more and 400 ° C. or less.