JP6967196B2 - Semiconductor device - Google Patents

Description

The present invention relates to semiconductor devices and electrical devices. The present invention particularly relates to a semiconductor device and an electric device provided with a joint portion capable of ensuring electrical connectivity when high temperature solder is used.

In the field of lead-free solder mounting technology, in a semiconductor device in which a semiconductor chip is mounted on the island portion of a lead frame and molded with a resin encapsulant, the lead frame material is made of resin to make the coefficient of thermal expansion about the same, and the mold resin is used. A semiconductor device is known in which a conductive metal thin layer is fixedly formed on the surface of at least a lead portion of the lead frame while ensuring adhesion to the lead frame (see, for example, Patent Document 1). ).

When joining the island part of the lead frame and the semiconductor chip with a solder material, depending on the joining process conditions, the conductive metal thin layer fixed and formed on the lead frame surface diffuses into the joining layer, and the metal thin layer thickness There is a concern that it will be difficult to secure electrical connectivity due to the reduction or disappearance of the solder.

As a measure to reduce the thin metal layer formed on the surface of the object to be joined, from the side close to the surface of the Zn alloy base material,
Ni plating layer (thickness 0.3 μm or more and 1.0 μm or less) and Sn plating layer (thickness 0.5 μm)
There is known a technique for preventing the diffusion of Zn by forming a film of 2.0 μm or less and heat-treating it under a temperature condition of 150 ° C. or higher and 170 ° C. or lower to leave a Sn plating layer. See Patent Document 2). Further, by preventing the diffusion of Zn, the ZnO (zinc oxide) layer is not formed and the electrical connectivity is ensured.

Japanese Unexamined Patent Publication No. 2000-277679 Japanese Unexamined Patent Publication No. 11-135226

However, when the above is applied to a reflow process of a high temperature solder material such as a Zn-based solder (melting point: 382 ° C.), the diffusion coefficient from Sn to Zn at a temperature of 400 ° C. is higher than the diffusion coefficient at a temperature of 170 ° C. considering that approximately 10 ⁵ times greater, Sn plating component is eluted into the bonding layer (solder) in the process, or is concerned that lead to loss. Specifically, Zn
The diffusion coefficient of Sn inward (D _{Sn → Zn} ) is 1.4 × ^10-20 m ² / s at 150 ° C.
At 170 ° C, it is 6.9 × ^10-20 m ² / s, whereas at 400 ° C, it is 6.9 ×.
It will be ^10-15 m ^{2 / s.} As a result, the underlying Ni plating diffuses into the solder, and Zn-N
It is assumed that the formation of the i-compound at the bonding interface increases the interface resistance, making it difficult to secure electrical connectivity.

Even in the reflow process using a Bi-based solder material (melting point: 262 ° C), which has a lower melting point than Zn-based solder, if the Sn plating component elutes or disappears in the bonding layer (solder) during the process, the bonding interface It is assumed that a Bi-Ni compound is formed in the solder and the interfacial resistance increases, making it difficult to secure electrical connectivity.

In order to solve the above problems, the present inventor has completed the present invention by considering forming a film for preventing the diffusion of Ni on the bonding surface of the object to be bonded having the Ni-treated layer on the surface or inside. I came to do. According to one embodiment, the present invention is a solder joint, comprising a Ni-treated film.
It is provided with at least an object to be bonded having a Sn diffusion preventing film on the bonding surface and a solder bonding layer formed by melting a solder material containing Bi or Zn as a main component.

In the solder joint portion, it is preferable that the object to be joined is a semiconductor element having a Sn diffusion prevention film on an electrode containing a Ni-treated film.

In the solder joint, the object to be joined has a Ni-treated film on the surface of the base material, and the Ni
A lead frame or a substrate electrode having a Sn diffusion prevention film on the treated film is preferable.

In the solder joint, the Sn diffusion prevention film is preferably 2 to 10 μm.

In the solder joint, the solder material containing Bi or Zn as a main component is Bi alone, Zn alone, or Bi or Zn in Sn, Sb, Ge, Ag, Cu, Ni, P, A.
It is preferable that the solder contains one or more additive elements selected from l and has a solid phase line temperature of 260 ° C. or higher.

According to another embodiment, the present invention relates to a semiconductor device including the solder joint according to any one of the above.

The present invention relates to an electrical device comprising the solder joint according to any of the above, according to another embodiment.

According to another embodiment, the present invention is a method for manufacturing a semiconductor device, in which a step of forming a Sn diffusion prevention film on a bonding surface of a bonded body provided with a Ni-treated film and a method of forming the bonded body with the bonded body. It includes a step of reflow bonding using a high-temperature solder material containing Bi or Zn as a main component and having a solid phase line temperature of 260 ° C. or higher.

In the method for manufacturing the semiconductor device, it is preferable that the step of forming the Sn diffusion prevention film is carried out by a method selected from vapor deposition, sputtering, electroplating, electroless plating, and hot-dip plating.

In the method for manufacturing a semiconductor device, the object to be joined provided with the Ni-treated film is a semiconductor element having an electrode containing the Ni-treated film and / or a lead frame or a substrate electrode having a Ni-treated film on the surface of the base material. Is preferable.

According to the solder joint portion according to the present invention, by forming the Sn diffusion prevention film, it is possible to suppress the diffusion and / or disappearance of the Ni-treated film to the joint layer in which the high-temperature solder material is melted. This makes it possible to provide a semiconductor device that ensures electrical connectivity.

FIG. 1 is a conceptual cross-sectional view of a semiconductor device including a solder joint according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing an evaluation sample according to an embodiment of the present invention. FIG. 3 is a photograph showing a cross section of a solder joint portion according to an embodiment of the present invention. FIG. 4 is a photograph showing a cross section of a solder joint portion according to a comparative example of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below.

The present invention relates to a solder joint according to one embodiment. The solder joint is S on the joint surface.
It is provided with at least an object to be bonded having an anti-diffusion film and a Ni-treated film, and a solder bonding layer obtained by melting a solder material containing Bi or Zn as a main component.

The solder joint may typically be a joint that joins a relatively large area of electrical equipment. Examples of the electric device include, but are not limited to, a semiconductor device, a lighting component using an LED element, an inverter drive circuit, a power converter, and the like. Preferably,
The electrical equipment is a semiconductor device, and the joint includes the joint between the lead frame and the electrode of the semiconductor die, the joint between the substrate electrode and the electrode of the semiconductor die, or the joint between the electrode of the semiconductor die and the implant pin. However, it is not limited to these. Hereinafter, the present invention will be described with reference to a die bond joint portion in a semiconductor device as an example, but the joint portion of the present invention is not joined to a specific joint portion of a specific device.

FIG. 1 is a conceptual cross-sectional view of a semiconductor module, which is an example of a semiconductor device including a solder joint according to an embodiment of the present invention. The semiconductor module 100 is mainly composed of a semiconductor element 1, a solder bonding layer 2, a lead frame 3, a wire 4, and a sealing resin 5 for molding these. In the illustrated semiconductor module 100, the semiconductor element 1, the solder bonding layer 2, and the lead frame 3 form the die bond bonding portion P.

In the illustrated embodiment, the objects to be joined are the semiconductor device 1 and the lead frame 3.
These are joined by the solder joining layer 2.

The solder joint layer 2 is formed by melting a solder material containing Bi or Zn as a main component. The solder material containing Bi or Zn as a main component is a solder material having a solid phase line temperature of 260 ° C. or higher, and is S.
Additive elements such as n, Sb, Ge, Ag, Cu, Ni, P, and Al may be contained.
It may also contain unavoidable impurities. Inevitable impurities are mainly Cu, Ni, Zn, Fe.
, Al, As, Cd, Ag, Au, In, P, Pb and the like. Further, the solder material according to the present invention is a lead-free solder containing no Pb. Hereinafter, in the present specification, the solder material may be referred to as a high temperature solder material.

Among such solder materials, the solder materials containing Bi as the main component include pure Bi and Bi-S.
n, Bi-Ge, Bi-Sb, Bi-Cu, Bi-Zn, Bi-Sn-Ag, Bi-Sb
-Ge, Bi-Sb-Ge-P, Bi-Sb-Ge-Ni, Bi-Sb-Ge-Ni-P
However, it is not limited to these. Further, examples of the solder material containing Zn as a main component include, but are not limited to, pure Zn, Zn-Bi, and Zn-Al-Ge.

The method for forming the solder joint layer 2 will be described later, but typically, the solder joint layer 2 may be formed by a reflow step of melting at a temperature equal to or higher than the solid phase temperature of the high temperature solder material.

Referring to FIG. 1 (b), both the semiconductor element 1 and the lead frame 3 to be joined are provided with Sn diffusion prevention films 10 and 30 on the joint surface, and are soldered to the inside of the joint surface (to the joint surface). Ni-treated films 11 and 31 are provided on the opposite side of the layer).

The lead frame 3 is provided with a Ni-treated film 31 on the surface of the Cu base material 32, and further Ni.
A Sn diffusion prevention film 30 is provided on the treated film 31. The Ni-treated film 31 is generally provided on the surface of a Cu member for the purpose of preventing rust, and may be an electroless Ni plating film, an electroless P-Ni plating film, or an electrolytic Ni plating film. Not limited to these. The film thickness of the Ni-treated film 31 can be appropriately determined depending on the intended purpose, and may be, for example, 0.1 to 5 μm.
It can be 0.5 to 3 μm, but is not limited to a specific film thickness.

The Sn diffusion prevention film 30 may be a plating film, a sputtering film, or the like formed on the Ni-treated film 31. Further, as long as it contains Sn as a main component, it may contain a component other than Sn. For example, it may be a film composed of one or more elements selected from Ag, Cu, Bi, Zn, Sb, Ge, and Ni and Sn, but is not limited thereto. In particular, when the main component of the solder material forming the solder bonding layer is Bi, it can be a Sn diffusion prevention film containing Sn and Bi, and when the main component of the solder material is Zn, it contains Sn and Zn. It can be a Sn diffusion prevention film. When the main component of the diffusion prevention film is Au or Ag, it diffuses into the solder joint layer and S
Since the effect of suppressing the diffusion of the surface-treated film of the i-chip or the lead frame into the bonding material is almost eliminated, Ag and Au are not suitable as the main component of the diffusion prevention film, and it is preferable to use Sn as the main component. If Sn is the main component, even if it contains Ag or the like, it does not affect the diffusion prevention function.

The thickness of the Sn diffusion prevention film 30 is preferably 2 to 10 μm when the Sn diffusion prevention film 30 is substantially composed of only Sn. A peak heating temperature of 350 is set to 2 μm or more.
This is because Sn is completely diffused into the solder joint layer under the reflow temperature profile conditions of ° C. and a heating time of 3 min, and as a result, the residual Sn plating film thickness is secured. The reason why the thickness is 10 μm or less is to prevent peeling. When Bi or Zn, which is the main component of the solder material, is contained in the Sn diffusion prevention film 30, this film thickness can be reduced according to the content of Bi or Zn. On the other hand, when the Sn diffusion prevention film 30 contains an element other than Bi or Zn, it is preferable that the Sn alone has a film thickness of 2 μm or more.

The lead frame shown in the figure is in contact with the Ni-treated film 31 to provide the Sn diffusion preventing film 30, but in other bonded objects, in some cases, between the Ni-treated film 31 and the Sn diffusion preventing film 30. Other layers may be provided for the purpose of improving solder wettability and wire bonding property. In this case, the other layer may be, for example, a 0.01 to 1 μm layer composed of Pd (palladium), Au (gold), or a combination containing these, but is not limited thereto. The lead frame material is a Cu base material (Cu-Fe-P, etc.) and an Fe base material (Fe-).
Any of (42% Ni, etc.) can be used.

The semiconductor element (silicon chip) 1 is provided with a Sn diffusion prevention film 10 on the back surface electrode.
More specifically, a general back electrode layer composed of a Ti layer 13, a Ni-treated film 11 and an Au layer 12 is formed on the Si crystal 14, and a Sn diffusion prevention film 10 is provided on the Au layer 12. There is. The thicknesses of the Ti layer 13, the Ni-treated film 11, and the Au layer 12 differ depending on the characteristics of the semiconductor element 1, and can be appropriately determined by those skilled in the art. Typically, the Ni-treated membrane 11 is electroless N.
It may be an i-plating film, an electroless P-Ni plating film, or an electrolytic Ni plating film, but is not limited thereto. The film thickness of the Ni-treated film 11 may be, for example, 0.1 to 5 μm, and may be 0.5 to 3 μm, but is not limited to a specific film thickness. The thickness of the Au layer 12 may be, for example, 0.01 to 0.3 μm, and 0.03 to 0.1 μm.
It can be m, but it is not limited to a specific film thickness.

The Sn diffusion prevention film 10 may be a plating film, a sputtering film, or the like formed on the Au layer 12, and the composition, forming method, film thickness, and the like thereof are the Sn diffusion prevention film 30 on the lead frame 3.
You can select from the same range as. The Sn diffusion prevention film 10 on the semiconductor element 1 and the Sn diffusion prevention film 30 on the lead frame 3 may have the same composition, forming method, film thickness, etc., and the composition, forming method, and film thickness may be the same. Any one or more of them may be different.

Next, a method of manufacturing a semiconductor device including such a solder joint will be described. The method for manufacturing a semiconductor device includes a step of forming a Sn diffusion prevention film on a bonding surface of a bonded body provided with a Ni-treated film, and the bonded body containing Bi or Ni as a main component and having a solid phase line temperature of 260. It includes a step of reflow joining using a high temperature solder material of ℃ or higher.

The step of forming the Sn diffusion preventing film on the bonding surface of the object to be joined provided with the Ni-treated film is a step of forming the Sn diffusion preventing film on the bonding surface of the lead frame, the substrate electrode, the semiconductor element, and the like. Sn
The diffusion prevention film can be formed by a method such as thin film deposition, sputtering, electroplating, electroless plating, and hot dip plating. Depending on the mode of the object to be bonded, a Sn diffusion prevention film may be formed on the surface of the Ni-treated film, and S may be formed on the film made of another material without coming into contact with the Ni-treated film.
n In some cases, a diffusion prevention film is formed. Those skilled in the art can use these methods to form a Sn diffusion-preventing film having the composition and film thickness described in detail above.

In the step of reflow joining the bonded body, the solder material is melted in a state where the solder material is in contact with the bonded body. The solder material may be a powder material used in combination with a flux, a plate material, or a wire material. When the powder material is used in combination with the flux, the solder material having an average particle size of 15 to 50 μm, preferably 25 to 40 μm can be used. This is because, in the range of the average particle size of 15 to 50 μm, the adjacent solder materials do not aggregate and can be stably produced. The flux can be appropriately selected by those skilled in the art according to the joining conditions and the like, and is not particularly limited, but a flux having a composition capable of suppressing the oxidation of Zn or Bi may be used. preferable. As an example, a halogen-activated rosin flux and the like can be mentioned. The wire may be, for example, a wire having a diameter of 200 to 1000 μm, and the plate may be, for example, a plate having a thickness of 50 to 200 μm.

For example, a thread-like or plate-shaped solder material is supplied onto one of the bonded objects, or a powdered solder material is supplied with flux on one of the bonded objects, and the other bonded body is mounted on the solder. And heat it. The heating temperature at this time is preferably set to be equal to or higher than the solidus temperature of the solder material, and the heating peak temperature is preferably set to about + 30 ° C. of the liquidus temperature of the solder material. Good wettability can be obtained by holding the heating time at least 60 seconds or more. Regarding the heating peak temperature, it is not always necessary to heat above the liquidus phase temperature, and in the case of components closer to pure Bi or pure Zn, heating at these solid phase temperature + 30 ° C. gives good bonding. Can be secured. The heating can also be carried out in an active atmosphere such as hydrogen or formic acid.

By manufacturing a semiconductor device provided with a junction having a Sn diffusion prevention film formed by the above steps, diffusion of the Ni-treated film into the junction layer is suppressed, and an intermetallic compound having low thermal shock resistance can be produced. It can be suppressed. That is, when the Sn diffusion preventing film does not exist, _Bi 3 Ni capable of forming the interface between the object to be bonded of the solder bonding layer, bini compounds such bini and, N
It is possible to suppress the formation of Zn—Ni compounds such as i ₂ Zn ₁₁ , NiZn ₃ , and Ni ₅ Zn _{21 to ensure electrical connectivity.}

The present invention is not limited to the illustrated embodiment. At least one of the objects to be bonded may have a Sn diffusion prevention film formed on the bonding surface and a Ni-treated film on the inside of the bonding surface (opposite to the solder bonding layer). Is not limited. Therefore, one of the illustrated Sn diffusion prevention films 10 or 30 may not be present. Further, if the Sn diffusion prevention film is formed on the joint surface of the object to be joined, it is not necessary that the Sn diffusion prevention film and the Ni-treated film are provided in contact with each other. The Ni-treated film is located near the bonding surface of the object to be bonded (for example, 0.1 to 5 μm), and is placed between the Sn diffusion prevention film and the Ni-treated film under the bonding temperature conditions of a high-temperature solder material. There may be a layer that is easy to diffuse. Specifically, a layer of 0.01 to 1 μm made of Ag, Pd, Au, etc. may be present between the Sn diffusion prevention film and the Ni-treated film. When the Sn diffusion prevention film is formed on the bonding surface of both of the two objects to be bonded via the solder bonding layer, the thickness and composition of the Sn diffusion prevention film and the Sn diffusion prevention film are formed. The positional relationship between the Ni-treated film and the Ni-treated film may be the same or different.

Further, as another aspect of the semiconductor device including the joint portion according to the present invention, although not shown, a semiconductor module having another configuration can be mentioned. Specifically, it may be a semiconductor module provided with an insulating substrate sandwiched between two upper and lower electrodes, and a plurality of semiconductor dies are bonded to the upper electrode of the insulating substrate. In this module, the semiconductor die is further connected with an aluminum wire (wire bonding), the copper wiring (copper bar) is pulled out from the upper electrode, and the semiconductor die, the electrode, the insulating substrate, and the aluminum wire are sealed with a sealing material. It has been stopped. Such a configuration is particularly preferably adopted in a semiconductor module on which a Si chip is mounted. In this case, the Sn diffusion prevention film can be formed on the Ni-treated film of the electrode of the insulating substrate and / or on the back surface electrode of the semiconductor die (the electrode bonded to the electrode of the insulating substrate).

Alternatively, as yet another embodiment, an insulating substrate sandwiched between two upper and lower copper blocks is provided.
It may be a semiconductor module in which a plurality of semiconductor dies are bonded on a copper block on the upper side of an insulating substrate and an implant pin is bonded on the semiconductor die. In this module, a printed circuit board is further bonded to the implant pin, and the semiconductor die, the copper block, the insulating substrate, the pin, and the printed circuit board are sealed with a sealing material. Such configurations, in particular, SiC
It is preferably used in semiconductor modules on which chips are mounted. In this case, the Sn diffusion prevention film is on the Ni-treated film of the copper block and / or the back electrode of the semiconductor die (the electrode to be bonded to the block) and / or the front surface electrode of the semiconductor die (bonded to the implant pin). Electrodes), which can be formed on the joint surface of the implant pin.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples show a typical aspect of the present invention and do not limit the present invention.

[Ni diffusion suppression effect and electrical property test]
[Example]
The joint according to the embodiment was manufactured. The object to be joined is 8.7 mm × 7.0 mm × t1.
A 4 mm lead frame and a 6 mm × 4.5 mm × t0.28 mm Si chip were used.
For the lead frame, a Ni surface-treated film having a film thickness of 2 μm is formed on the Fe base material (Fe-42% Ni), and a Sn diffusion-preventing film having a film thickness of 2 μm is electroplated on the Ni-treated film as a diffusion-preventing film. It was formed in. On the other hand, the surface treatment of the Si chip was composed of Ti / Ni / Au from the Si chip side, and the film thicknesses were Ti: 0.8 μm, Ni: 1 μm, and Au: 0.03 μm, respectively.
Further, a Sn diffusion prevention film having a film thickness of 2 μm was formed on the Au surface treatment layer as a diffusion prevention film by the same method as described above.

Using a die bonder, a thread solder made of pure Bi having a diameter of 0.8 mm was supplied onto the lead frame. After that, the Si chip is mounted on the solder so that the Sn diffusion prevention film comes into contact with the solder and scrubbed, and the heating temperature is 320 ° C., N ₂ + 10% H ₂ atmosphere (gas flow rate: 2).
.. By joining at 25 L / min), the example sample shown in FIG. 2 was prepared.

FIG. 3 shows the cross-sectional observation results of the Si chip / lead frame bonding on which the Sn diffusion prevention film is formed. FIG. 3A is a scanning micrograph, in which the lead frame 3 and the Si chip 1 which are the objects to be bonded can be observed in contact with the solder bonding layer 2. FIG. 3B is an elemental analysis result of Ni by EDX mapping. Ni-treated layers 11 and 31 are observed, but diffusion into the solder joint layer 2 is not observed. FIG. 3C is an elemental analysis result of Bi by EDX mapping. It can be confirmed that Bi is present in the solder joint layer. FIG. 3 (d) shows the ED.
It is the elemental analysis result of Sn by X mapping. The presence of Sn diffusion prevention films 10 and 30 (the portion surrounded by the dotted line) can be confirmed on both sides of the solder joint layer 2. From these observation results, Sn-N is found at the interface between the Si chip and the solder joint layer and at the interface between the solder joint layer and the lead frame.
It was confirmed that an i-based compound was formed and suppressed the diffusion of Ni into the solder joint layer.

S consisting of Sn plating with a film thickness of 2 μm on the surface-treated film of the Si chip and lead frame.
An electrical property test of a semiconductor device in which an diffusion prevention film was formed and diffusion of Ni, which is a surface treatment film component, was suppressed was performed. As a result, it was also found that the Idss (gate, drain when short-circuited between sources, current between sources) satisfies the standard value, so that it is possible to secure electrical connectivity. This experiment was performed on Bi solder, but the diffusion suppression effect of Ni by the Sn diffusion prevention film is also confirmed in the bonding with Zn-based solder material.

[Comparison example]
In the above example, a comparative example sample was prepared in the same manner as above except that the Sn diffusion prevention film was not provided on either the Si chip or the lead frame. FIG. 4 shows the cross-sectional observation results of the Si chip / lead frame junction in the comparative example. FIG. 4A is a scanning micrograph, in which the compound X of Ni and Bi is seen at the interface between the objects 1 and 3 to be bonded and the solder bonding layer 2.
FIG. 4B is an elemental analysis result of Ni by EDX mapping. Ni treatment layer 11, 3
1 is observed, and the Ni component which is further diffused into the solder joint layer 2 to form the compound X is observed. FIG. 4C is an elemental analysis result of Bi by EDX mapping. It can be confirmed that Bi is present in the solder joint layer. FIG. 4 (d) shows S by EDX mapping.
It is an elemental analysis result of n. In the comparative example, the Sn diffusion prevention film is not formed, and the presence of Sn cannot be confirmed. From these observation results, in the joint portion of the comparative example, N, which is a component of the Ni-treated film, is used.
i diffuses and B at the Si chip / solder joint interface and the solder / lead frame joint interface
It was confirmed that the i-Ni compound X had abnormal growth (compound layer thickness: maximum 23 μm). The Ni-treated film on the Si chip 1 was thinned from 1 μm to 0.3 μm, and the Ni-treated film on the lead frame 3 was thinned from 2 μm to 0.7 μm. Depending on the bonding process conditions, diffusion may proceed further, leading to the disappearance of the Ni-treated membrane.

As a result of the electrical characteristic test of the semiconductor device of the comparative example, it was confirmed that Idss did not satisfy the standard value and the electrical connectivity could not be ensured.

[Evaluation of Sn diffusion prevention film film thickness]
From the heat resistance of Si chips of discrete products, a peak heating temperature of 350 ° C. or less and a heating time of 3 min or less are required as reflow process conditions. When Sn plating is formed on the surface of the Si chip with the aim of 2 μm (average value), the film thickness range is 1.6 μm to 2.4 μm in consideration of the film thickness variation ± 0.4 μm. Sn plating 2 μm was formed on a Si chip of 3 mm × 3 mm × t0.45 mm. As the bonding layer, the same pure Bi solder as in the examples was used.
Under the above reflow temperature profile conditions, Sn was completely diffused into the bonding layer, resulting in a minimum residual Sn plating film thickness of 0.2 μm. That is, the amount of Sn plating film reduction of the object to be joined is 1.4 μm, and it is necessary to form a Sn plating film having an average of at least 2 μm. Therefore, the lower limit of the Sn plating film thickness to be formed on the surface-treated film of the Si chip or the lead frame is set to 2 μm.

A Sn plating diffusion prevention film was formed on Cu of 10 mm × 10 mm × t1 mm. Table 2 shows the results of investigating the state of peeling occurrence using the Sn diffusion prevention film thickness as a parameter. For the plating peeling judgment, the white part of the ultrasonic flaw detection image or the peeled part was specified by observing the cross section, and if there was no peeling, it was marked as ◯, and if peeling occurred, it was marked as x. When the Sn diffusion prevention film thickness was 11 μm or more, plating peeling was confirmed. Sn diffusion prevention film thickness variation ± 0.
Considering 6 μm, the upper limit of the film thickness of the diffusion prevention film is preferably 10 μm.

The joint according to the present invention is used for a die bond joint. In particular, it is suitably used for package parts such as ICs. Further, it is suitably used for a joint portion of a component that generates a large amount of heat, for example, an LED element, a junction portion of a power semiconductor device such as a power diode, and a junction portion such as an IC element in all electronic components mounted on a printed wiring board or the like. Examples of applied products include lighting components using the LED elements described above, inverter drive circuits, and power converters called power modules.

1 Semiconductor element 10 Sn diffusion prevention film 11 Ni-treated film 12 Au
13 Ti
14 Si
2 Solder joint layer 3 Lead frame 30 Sn diffusion prevention film 31 Ni-treated film 32 Cu
4 Wire 5 Encapsulant 100 Semiconductor module

Claims (9)

A solder joint portion provided with at least a solder joint layer provided with a Ni-treated film and a Sn diffusion prevention film containing Sn and Bi on the joint surface, and a solder joint layer formed by melting a solder material containing Bi as a main component. .. The solder joint portion according to claim 1, wherein the bonded body is a semiconductor element in which an electrode layer including a Ti layer, a Ni-treated film, and an Au layer is formed, and the Sn diffusion prevention film is provided on the electrode layer. The solder joint portion according to claim 1 or 2, wherein the bonded body is a lead frame or a substrate electrode having a Ni-treated film on the surface of the base material and the Sn diffusion preventing film on the Ni-treated film. The solid-state temperature of the solder material containing Bi as a main component is a simple substance of Bi, or Bi contains one or more additive elements selected from Sn, Sb, Ge, Ag, Cu, Ni, P, and Al. The solder joint according to any one of claims 1 to 3, wherein the solder is a high-temperature solder having a temperature of 260 ° C. or higher. A semiconductor device including the solder joint according to any one of claims 1 to 4. An electric device including the solder joint according to any one of claims 1 to 4. The process of forming a Sn diffusion prevention film on the joint surface of the object to be joined provided with the Ni-treated film, and
The method for manufacturing a semiconductor device according to claim 5, further comprising a step of reflow joining the bonded body using a high-temperature solder material containing Bi as a main component and having a solid phase line temperature of 260 ° C. or higher. The method according to claim 7, wherein the step of forming the Sn diffusion prevention film is carried out by a method selected from vapor deposition, sputtering, electroplating, electroless plating, and hot-dip plating. 6. the method of.

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