JP6142584B2 - Metal composite, circuit board, semiconductor device, and method for manufacturing metal composite - Google Patents

Description

  The present invention relates to a metal composite in which a metal member is disposed on one surface or the other surface of an insulating layer, a circuit board made of the metal composite, a semiconductor device including the circuit board, and manufacture of the metal composite It is about the method.

Examples of the metal composite in which the metal member is disposed on one surface or the other surface of the insulating layer include an LED and a semiconductor device of a power module. This semiconductor device has a structure in which a semiconductor element is bonded on a circuit layer made of a conductive material.
In a power semiconductor element for large power control used for controlling an electric vehicle such as wind power generation or an electric vehicle, the amount of heat generated is large. Therefore, as a substrate on which the power semiconductor element is mounted, for example, AlN (aluminum nitride) 2. Description of the Related Art Conventionally, a circuit board in which a metal plate having excellent conductivity is bonded as a circuit layer (metal member) on a ceramic substrate (insulating layer) made of has been widely used. Further, a metal plate may be bonded as a metal layer (metal member) to the surface of the ceramic substrate opposite to the circuit layer.
In the power module shown in Patent Document 1, a semiconductor element and a heat sink are joined to one surface and the other surface of a circuit board via solder, and heat generated in the semiconductor element is transmitted to the ceramic substrate side. In addition, it is configured to dissipate outside through a heat sink.

  By the way, when an electronic component such as a semiconductor element and a circuit layer are joined via a solder material as in the power module described in Patent Document 1, a part of the solder is used when used in a high temperature environment. There is a possibility that the bonding reliability between the electronic component such as a semiconductor element and the circuit layer is lowered due to melting. Further, even when the heat sink and the metal layer are bonded via the solder material, there is a risk that the bonding reliability similarly decreases.

  On the other hand, the power module shown in Patent Document 2 has a configuration in which a heat sink and a metal layer are joined via a brazing material. As described above, when the heat sink and the metal layer are bonded via the brazing material, the melting point of the brazing material is higher than the melting point of the solder material, so that the bonding reliability in a high temperature environment is improved. Therefore, there is a problem that the circuit board deteriorates due to heat.

As an alternative to the solder material and the brazing material described above, for example, Non-Patent Document 1 proposes a technique for joining semiconductor elements using an Ag paste (joining material) containing Ag particles and an organic substance.
The Ag paste described in Non-Patent Document 1 contains Ag particles and organic matter, and by sintering the Ag particles, a bonding layer made of a conductive fired body is formed. Thus, an electronic component such as a semiconductor element is bonded onto the circuit layer. In the bonding using the Ag paste, the circuit layer and the electronic component are bonded to each other through the above-described bonding layer after the plating of NiAu, Ag, or the like is previously formed on the surface of the circuit layer or the electronic component.

Patent Document 3 proposes a technique for joining an electronic component such as a semiconductor element on a circuit board using a silver oxide paste (joining material) containing silver oxide particles and a reducing agent made of an organic substance. .
In the silver oxide paste described in Patent Document 3, the Ag particles produced by the silver oxide particles being reduced by the reducing agent are sintered, whereby a bonding layer made of a conductive fired body is formed. An electronic component such as a semiconductor element is bonded onto the circuit layer via the bonding layer.
As described above, when the bonding layer is formed by the sintered body of Ag particles, the bonding layer can be formed at a relatively low temperature and the melting point of the bonding layer itself is increased, so that the bonding strength is greatly reduced even in a high temperature environment. do not do.

JP 2004-172378 A JP 2008-16813 A Japanese Patent No. 4895994

C. Gobl and two others "Low temperature Sinter technology technology attachment for automotive power electronic applications" (France)

  By the way, as disclosed in Non-Patent Document 1, when a semiconductor element or a heat sink is bonded to a circuit board using Ag paste without using a solder material or a brazing material, plating is previously formed on the bonding surface. However, since the bonding strength between the plating and the sintered body of Ag particles is low, there is a problem that the bonding reliability is lowered.

  Moreover, as disclosed in Patent Document 3, when a semiconductor element or a heat sink is bonded to a circuit board using a silver oxide paste, an oxide is formed on the surface of the metal constituting the circuit layer or the metal layer. For this reason, there is a problem that the bonding reliability is lowered.

  The present invention has been made in view of the above-described circumstances, and is a bonding layer made of a fired body of a bonding material containing a metal member and another member, at least one of Ag particles and silver oxide particles, or both, and an organic material. A metal composite capable of improving the reliability of joining to other members when joining via a metal substrate, a circuit board comprising the metal composite, a semiconductor device including the circuit board, and a metal composite An object is to provide a manufacturing method.

In order to solve the above-mentioned problems, a metal composite of the present invention is a metal composite comprising an insulating layer and a metal member disposed on one surface or the other surface of the insulating layer. The metal member is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer, and the surface of the metal member opposite to the surface on which the insulating layer is disposed is for Ag sintered joining. The Ag underlayer is formed of an Ag foil, the element of the metal member is diffused in the Ag underlayer, and the Ag underlayer Ag is contained in the metal member. It is characterized by being diffused .

  According to the metal composite of the present invention, an Ag underlayer for Ag sintering bonding is formed by solid phase diffusion bonding on the surface of the metal member opposite to the surface on which the insulating layer is disposed. An Ag underlayer having high bonding strength can be formed on the metal member. The metal member on which the Ag underlayer is thus formed is bonded to another member via a bonding layer made of a sintered body of a bonding material containing at least one or both of Ag particles and silver oxide particles and an organic substance. In this case, the Ag underlayer and the bonding layer are bonded between the same kind of metals, and the bonding strength between the Ag underlayer and the bonding layer can be improved. Therefore, it is possible to sufficiently secure the bonding strength between the metal member and the other member, and the bonding reliability can be improved.

Further, the circuit board of the present invention is composed of the above-described metal composite, and includes a circuit layer composed of the metal member disposed on one surface of the insulating layer, and the circuit layer includes copper, aluminum, or a laminated body of the aluminum layer and the copper layer, on a surface thereof opposite to the surface on which the insulating layer is disposed within the circuit layer, Ag underlayer for Ag sintered joint is formed, the Ag The underlayer is composed of an Ag foil, and the element of the circuit layer is diffused in the Ag underlayer, and Ag of the Ag underlayer is diffused in the circuit layer .
According to the circuit board of the present invention, since the Ag underlayer for Ag sintering bonding is formed on the circuit layer of the circuit board, the bonding material containing at least one or both of Ag particles and silver oxide particles and an organic substance is used. When the semiconductor element or the like and the circuit layer are bonded via the bonding layer made of the fired body, the bonding strength between the semiconductor element or the like and the circuit layer can be ensured.

Furthermore, the circuit board of the present invention is composed of the above-mentioned metal composite, and is composed of a circuit layer disposed on one surface of the insulating layer and the metal member disposed on the other surface of the insulating layer. A metal layer, and the metal layer is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer, and on the surface of the metal layer opposite to the surface on which the insulating layer is disposed. An Ag underlayer for Ag sintering bonding is formed, the Ag underlayer is composed of an Ag foil, and the element of the metal layer is diffused into the Ag underlayer, and the Ag underlayer is dispersed in the metal layer. A structure in which Ag of the Ag underlayer is diffused may be employed.
According to the circuit board of the present invention, since the Ag underlayer for Ag sintering bonding is formed on the metal layer of the circuit board, the bonding material containing at least one or both of Ag particles and silver oxide particles and an organic substance is used. When joining a metal layer and a heat sink etc. via the joining layer which consists of a sintered body, the joint strength of a metal layer, a heat sink, etc. is securable.

The circuit board of the present invention comprises the above-described metal composite, and comprises the circuit layer disposed on one surface of the insulating layer and the metal member disposed on the other surface of the insulating layer. A metal layer, and the circuit layer is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer, and on the surface of the circuit layer opposite to the surface on which the insulating layer is disposed. An Ag underlayer for Ag sintering bonding is formed, and the Ag underlayer is composed of an Ag foil, and the elements of the circuit layer are diffused into the Ag underlayer, and the Ag underlayer is dispersed in the circuit layer. A structure in which Ag of the Ag underlayer is diffused may be employed.
According to the circuit board of the present invention, since the Ag underlayer for Ag sintering bonding is formed on the circuit layer of the circuit board, the bonding material containing at least one or both of Ag particles and silver oxide particles and an organic substance is used. When bonding a semiconductor element or the like and a circuit layer through a bonding layer made of a fired body, the bonding strength between the semiconductor element or the like and the circuit layer can be ensured and disposed on the other surface of the insulating layer. Since the metal layer made of the formed metal member is provided, when the circuit board and the heat sink or the like are bonded and a thermal stress is applied, the bonding reliability between the circuit board and the heat sink or the like can be ensured.

In addition, a semiconductor device of the present invention includes the above-described circuit board and a semiconductor element bonded to the Ag base layer, and firing a bonding material including at least one or both of Ag particles and silver oxide particles and an organic substance. The Ag underlayer and the semiconductor element are bonded by a bonding layer made of a body.
According to the semiconductor device of the present invention, the Ag underlayer and the semiconductor element as described above are bonded by the bonding layer made of the sintered body of the bonding material containing at least one or both of the Ag particles and the silver oxide particles and the organic material. Therefore, the bonding strength between the circuit board and the semiconductor element can be increased, and the bonding reliability can be improved.

The method for producing a metal composite of the present invention is a method for producing a metal composite in which a metal member is disposed on one surface or the other surface of an insulating layer, and the metal member is made of copper, aluminum, or A step of disposing the metal member on one surface or the other surface of the insulating layer , and comprising a laminate of an aluminum layer and a copper layer, and a side of the metal member opposite to the surface on which the insulating layer is disposed A step of disposing an Ag foil on the surface, and a step of solid-phase diffusion bonding the metal member and the Ag foil to form an Ag underlayer for Ag sintering bonding. Yes.

According to the method for producing a metal composite of the present invention, the step of disposing Ag foil or Ag powder on the surface of the metal member opposite to the surface on which the insulating layer is disposed; the metal member; A step of solid-phase diffusion bonding of Ag foil or Ag powder to form an Ag underlayer for Ag sintering bonding, so that an Ag underlayer for Ag sintering bonding is reliably formed on the metal member. be able to.
And the Ag underlayer formed in this way has good bondability with a bonding layer made of a fired body of a bonding material containing at least one or both of Ag particles and silver oxide particles and an organic material, and a metal member and When other members are bonded via the bonding layer, the bonding reliability can be improved.

  According to the present invention, when a metal member and another member are joined via a joining layer made of a sintered body of a joining material containing at least one or both of Ag particles and silver oxide particles and an organic material, the other members are joined. It is possible to provide a metal composite capable of improving the bonding reliability with the semiconductor, a circuit board made of the metal composite, a semiconductor device including the circuit board, and a method for manufacturing the metal composite.

1 is a schematic explanatory diagram of a semiconductor device according to a first embodiment of the present invention. It is a flowchart explaining the manufacturing method of the semiconductor device which concerns on 1st embodiment. It is a schematic explanatory drawing of the manufacturing method of the semiconductor device which concerns on 1st embodiment. It is a schematic explanatory drawing of the semiconductor device which concerns on 2nd embodiment of this invention. It is a schematic explanatory drawing of the circuit board which concerns on 2nd embodiment. It is a schematic explanatory drawing of the heat sink which concerns on 2nd embodiment. It is a flowchart explaining the manufacturing method of the semiconductor device which concerns on 2nd embodiment. It is a schematic explanatory drawing of the manufacturing method of the circuit board which concerns on 2nd embodiment. It is a schematic explanatory drawing of the manufacturing method of the semiconductor device which concerns on 2nd embodiment. It is a schematic explanatory drawing of the semiconductor device which concerns on 3rd embodiment of this invention. It is a flowchart explaining the manufacturing method of the semiconductor device which concerns on 3rd embodiment. It is a schematic explanatory drawing of the manufacturing method of the semiconductor device which concerns on 3rd embodiment. It is a schematic explanatory drawing of the semiconductor device which concerns on 4th embodiment of this invention. It is a schematic explanatory drawing of the joining interface of the aluminum layer and copper layer in the semiconductor device of FIG. It is a flowchart explaining the manufacturing method of the semiconductor device which concerns on 4th embodiment. It is a schematic explanatory drawing of the manufacturing method of the semiconductor device which concerns on 4th embodiment.

(First embodiment)
Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of the present invention will be described.
FIG. 1 shows a semiconductor device 1 according to the first embodiment of the present invention. The semiconductor device 1 includes a circuit board 10 (metal composite) and a semiconductor element 3 bonded to one surface (upper surface in FIG. 1) of the circuit board 10 via a bonding layer 2.

  As shown in FIG. 1, the circuit board 10 includes a ceramic substrate 11 constituting an insulating layer and a circuit layer 12 (metal member) disposed on one surface (the upper surface in FIG. 1) of the ceramic substrate 11. I have.

The ceramic substrate 11 is made of highly insulating AlN (aluminum nitride), Si ₃ N ₄ (silicon nitride), Al ₂ O ₃ (alumina), or the like. In this embodiment, it is comprised with AlN (aluminum nitride) excellent in heat dissipation. In addition, the thickness of the ceramic substrate 11 is set within a range of 0.2 to 1.5 mm, and in this embodiment is set to 0.635 mm.

The circuit layer 12 is formed by bonding a conductive copper metal plate to one surface (the upper surface in FIG. 1) of the ceramic substrate 11. In the present embodiment, the circuit layer 12 is formed by joining copper rolled sheets having a purity of 99.99% by mass or more. Note that the thickness of the circuit layer 12 is set in a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.6 mm in the present embodiment.
On one surface of the circuit layer 12, an Ag underlayer 12a made of Ag foil is formed.

  The Ag underlayer 12a is an underlayer for Ag sintering bonding. In this embodiment, the Ag underlayer 12a is formed by solid-phase diffusion bonding of an Ag foil having a purity of 99% or more to one surface of the circuit layer 12. Yes. The thickness of the Ag foil is set in a range of 0.003 mm or more and 0.1 mm or less, and is set to 0.01 mm in the present embodiment. Note that the Ag base layer 12 a is formed in a region bonded to the semiconductor element 3 on one surface of the circuit layer 12.

The semiconductor element 3 is made of a semiconductor material such as Si. The semiconductor element 3 and the circuit layer 12 are bonded via the bonding layer 2.
The joining layer 2 is a fired body of a joining material containing at least one or both of Ag particles and silver oxide particles and an organic substance, and in the present embodiment, an oxidation containing silver oxide particles and a reducing agent made of an organic substance. It is a fired body of silver paste. That is, the bonding layer 2 is an Ag fired body obtained by reducing silver oxide. Here, since the particles produced by reducing silver oxide are very fine, for example, with a particle size of 10 nm to 1 μm, a dense Ag fired layer is formed.

The silver oxide paste contains silver oxide powder (silver oxide particles), a reducing agent, a resin, and a solvent. In this embodiment, in addition to these, an organic metal compound powder is contained.
The content of the silver oxide powder is 60% by mass or more and 92% by mass or less of the entire silver oxide paste, and the content of the reducing agent is 5% by mass or more and 20% by mass or less of the entire silver oxide paste. The content is 0% by mass or more and 10% by mass or less of the entire silver oxide paste, and the remainder is a solvent. In this silver oxide paste, a dispersant and a resin are not added in order to prevent unreacted organic matter from remaining in the bonding layer 2 obtained by sintering.

The reducing agent is an organic substance having reducibility, and for example, alcohol and organic acid can be used.
The organometallic compound has an action of promoting the reduction reaction of silver oxide and the decomposition reaction of organic substances by the organic acid generated by thermal decomposition, for example, formic acid Ag, acetic acid Ag, propionic acid Ag, benzoic acid Ag, oxalic acid. A carboxylic acid metal salt such as Ag is applied.
The silver oxide paste has a viscosity adjusted to 10 Pa · s to 500 Pa · s, more preferably 50 Pa · s to 300 Pa · s.

Next, a method for manufacturing the semiconductor device 1 according to the present embodiment will be described with reference to a flowchart shown in FIG.
First, the copper plate 23 is bonded to one surface of the ceramic substrate 11 using a copper member bonding paste containing Ag and a nitride-forming element to form the circuit layer 12 (circuit layer forming step S01). Here, the copper member bonding paste contains a powder component containing Ag and a nitride-forming element, a resin, a solvent, a dispersant, a plasticizer, and a reducing agent. In addition to Ag and nitride forming elements, one or more additive elements selected from In, Sn, Al, Mn and Zn are included.

  Specifically, as shown in FIG. 3, Ag and the nitride forming element layer 25 are formed by applying a copper member bonding paste to one surface of the ceramic substrate 11 by screen printing and drying. The thickness of the Ag and nitride forming element layer 25 is set to 60 μm or more and 300 μm or less after drying. Next, the copper plate 22 is laminated on one surface side of the ceramic substrate 11. That is, the Ag and nitride forming element layer 25 is interposed between the ceramic substrate 11 and the copper plate 22.

Then, by inserting and heating the copper plate 22 and the ceramic substrate 11 in a vacuum heating furnace in a state in which the copper plate 22 and the ceramic substrate 11 are pressurized in the stacking direction (pressure 1 to 35 kgf / cm ² ), the circuit layer 12 is formed on one surface of the ceramic substrate 11. Form. During this heating, Ag and Ag in the nitride-forming element layer 25 diffuse toward the copper plate 22. At this time, a part of the copper plate 22 is melted by a eutectic reaction between Cu and Ag, and a molten metal region is formed at the interface between the copper plate 22 and the ceramic substrate 11. Then, when the molten metal region is solidified, the ceramic substrate 11 and the copper plate 22 are joined, and the circuit layer 12 is formed.
Here, in this embodiment, the pressure in the vacuum heating furnace is set in a range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, and the heating temperature is set in a range of 790 ° C. to 850 ° C.
In addition, after the solidification is completed, Ag and Ag of the nitride forming element layer 25 are sufficiently diffused, and the Ag and nitride forming element layer 25 does not remain at the bonding interface between the ceramic substrate and the copper plate. .

Next, the Ag foil 22a is laminated on one surface of the circuit layer 12 (Ag foil lamination step S02).
Next, the ceramic substrate 11 on which the Ag foil 22a and the circuit layer 12 are formed is inserted in a vacuum heating furnace in a state where the ceramic substrate 11 is pressurized (pressure 1 to 35 kgf / cm ² ) in the stacking direction, and the Ag foil 22a and the circuit are heated. The layer 12 is solid phase diffusion bonded to form an Ag underlayer 12a for Ag sintering bonding (Ag underlayer forming step S03).

Here, in this embodiment, in the Ag underlayer forming step S03, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is 350 ° C. to 779 ° C., and the holding time is It is set within the range of 15 minutes or more and 270 minutes or less. Further, a more preferable heating temperature is in a range from a temperature 5 ° C. lower than the eutectic temperature of Ag and Cu (779.1 ° C.) to a temperature lower than the eutectic temperature.
The surface to be joined between the circuit layer 12 and the Ag foil 22a is solid-phase diffusion bonded after the scratches on the surface have been removed and smoothed in advance.
As described above, the circuit board 10 according to the present embodiment is manufactured.

Next, the silver oxide paste 4 to be the bonding layer 2 is applied to the surface of the Ag base layer 12a (silver oxide paste application step S04).
In addition, when apply | coating the silver oxide paste 4, various means, such as a screen printing method, an offset printing method, and a photosensitive process, are employable. In the present embodiment, the silver oxide paste 4 is printed by a screen printing method.

Next, after the silver oxide paste 4 is applied and dried (for example, stored at room temperature in an air atmosphere for 24 hours), the semiconductor element 3 is stacked on the silver oxide paste 4 of the circuit board 10 (semiconductor element stacking step). S05).
Then, the semiconductor element 3 and the circuit board 10 are stacked and placed in a heating furnace, and the silver oxide paste 4 is fired (firing step S06). At this time, the semiconductor element 3 and the circuit board 10 can be bonded more reliably by heating in a state where the semiconductor element 3 and the circuit board 10 are pressurized in the stacking direction. In this case, the pressurizing pressure is desirably 0.5 to 10 MPa.
In this way, the bonding layer 2 is formed on the Ag base layer 12a, and the semiconductor element 3 and the circuit layer 12 are bonded. Thereby, the semiconductor device 1 which is this embodiment is manufactured.

  According to the semiconductor device 1 and the circuit board 10 according to the present embodiment configured as described above, the circuit layer 12 and the Ag foil 22a are joined by solid phase diffusion bonding to form the Ag base layer 12a. Therefore, the bonding strength between the circuit layer 12 and the Ag base layer 12a can be sufficiently increased. And since the circuit board 10 and the semiconductor element 3 in which this Ag base layer 12a was formed are joined via the joining layer 2 which consists of a baking body of the silver oxide paste 4, Ag base layer 12a and the joining layer 2 And the same kind of metal (Ag) are bonded to each other, and the bonding strength between the Ag base layer 12a and the bonding layer 2 can be improved. Therefore, it is possible to sufficiently secure the bonding strength between the circuit board 10 and the semiconductor element 3 and improve the bonding reliability.

In the present embodiment, the solid phase diffusion bonding between the circuit layer 12 and the Ag foil 22a is performed in a state where the circuit layer 12 and the Ag foil 22a are stacked and a pressure of 1 to 35 kgf / cm ² is applied in the stacking direction. Since it is configured to be maintained at 350 ° C. or higher and 779 ° C. or lower, Ag atoms of the Ag foil 22a are solid-phase diffused in the circuit layer 12 made of Cu, and Cu atoms of the circuit layer 12 are solid-phase diffused in the Ag foil 22a. The Ag base layer 12a can be reliably formed on one surface of the circuit layer 12 by diffusion and solid phase diffusion bonding.

When the pressure applied to the circuit layer 12 and the Ag foil 22a during solid phase diffusion bonding is less than 1 kgf / cm ^2, it becomes difficult to sufficiently bond the circuit layer 12 and the Ag foil 22a. There may be a gap between the foil 22a. Moreover, when it exceeds 35 kgf / cm < ² >, since the load applied is too high, the ceramic substrate 11 may be cracked. For these reasons, the pressure applied during solid phase diffusion bonding is set in the above range.

  When the temperature at the time of solid phase diffusion bonding is 350 ° C. or higher, diffusion of Ag atoms and Cu atoms is promoted, and solid phase diffusion can be sufficiently achieved in a short time. Moreover, in the case of 779 degrees C or less, it can suppress that the liquid phase of Ag and Cu arises, a bump arises in a joining interface, or thickness changes. Therefore, the preferable temperature range of solid phase diffusion bonding is set to the above range.

  A more desirable heating temperature at the time of solid phase diffusion bonding is in a range from 5 ° C. lower than the eutectic temperature below the eutectic temperature of Ag and Cu (779.1 ° C.). When such a temperature range is selected, the liquid phase is not formed and the compound of Ag and Cu is not generated. Therefore, in addition to improving the bonding reliability of the solid phase diffusion bonding, the solid phase diffusion bonding can be performed. Diffusion rate is fast and solid phase diffusion bonding can be performed in a relatively short time.

  In addition, when there are scratches on the surfaces to be joined when solid phase diffusion bonding is performed, gaps may occur during solid phase diffusion bonding. In this embodiment, the circuit layer 12 and the Ag foil 22a are bonded. Since the surfaces are solid-phase diffusion bonded after the surface scratches have been removed and smoothed in advance, it is possible to bond the surfaces while suppressing the formation of gaps at the respective bonding interfaces.

  In the present embodiment, since the bonding layer 2 is a fired body of the silver oxide paste 4 containing silver oxide powder and a reducing agent, the silver oxide is reduced by the reducing agent when the silver oxide paste 4 is fired. By being reduced, it becomes fine Ag particles, and the bonding layer 2 can have a dense structure. Further, since the reducing agent is decomposed when the silver oxide is reduced, it is difficult to remain in the bonding layer 2 and the conductivity and strength in the bonding layer 2 can be ensured. Furthermore, since the silver oxide paste 4 can be fired under a relatively low temperature condition such as 300 ° C., for example, the bonding temperature of the semiconductor element 3 can be kept low, and the thermal load on the semiconductor element 3 can be reduced. Can do.

(Second embodiment)
Next, a second embodiment of the present invention will be described. In addition, about the thing of the same structure as 1st embodiment, the same code | symbol is attached | subjected and described, and detailed description is abbreviate | omitted.

  FIG. 4 shows a semiconductor device 101 according to the second embodiment of the present invention. The semiconductor device 101 includes a circuit board 110, a semiconductor element 3 bonded to one surface (the upper surface in FIG. 4) of the circuit board 110 via a bonding layer 2, and a bonding layer on the other surface of the circuit board 110. 5 and a heat sink 130 joined through 5.

As shown in FIG. 5, the circuit board 110 includes a ceramic substrate 11, a circuit layer 12 disposed on one surface of the ceramic substrate 11 (upper surface in FIG. 5), and the other surface of the ceramic substrate 11 (see FIG. 5). 5 and a metal layer 113 disposed on the lower surface.
The circuit layer 12 has the same configuration as that of the first embodiment, and an Ag base layer 12a made of Ag foil is formed on one surface of the circuit layer 12.

The metal layer 113 is formed by joining a conductive aluminum metal plate to the other surface (the upper surface in FIG. 5) of the ceramic substrate 11. In the second embodiment, the metal layer 113 is formed by joining aluminum rolled sheets having a purity of 99.99% by mass or more. Note that the thickness of the metal layer 113 is set in a range of 0.1 mm or more and 1.0 mm or less, and in the present embodiment, is set to 0.6 mm.
An Ag underlayer 113a made of Ag foil is formed on the surface of the metal layer 113 opposite to the surface to which the ceramic substrate 11 is bonded. The Ag underlayer 113a has the same configuration as the Ag underlayer 12a described in the first embodiment, and is formed as an underlayer for Ag sintering bonding.

The heat sink 130 is for dissipating heat on the circuit board 110 side. The heat sink 130 is preferably made of a material having good thermal conductivity. In the present embodiment, the heat sink 130 is made of A6063 (Al alloy). The heat sink 130 is provided with a flow path 131 through which a cooling fluid flows.
On one surface of the heat sink 130 (the upper surface in FIG. 6), as shown in FIG. 6, an Ag base layer 130a made of Ag foil is formed. The Ag underlayer 130a has the same configuration as the above-described Ag underlayers 12a and 113a, and is formed as an underlayer for Ag sintered joining.

  Similar to the bonding layer 2, the bonding layer 5 is a sintered body of a bonding material containing at least one or both of Ag particles and silver oxide particles and an organic material. In the present embodiment, the bonding layer 5 is made of silver oxide particles and an organic material. And a sintered body of a silver oxide paste containing a reducing agent.

Next, a method for manufacturing the semiconductor device 101 and the circuit board 110 according to the present embodiment will be described with reference to a flowchart shown in FIG.
First, as in the first embodiment, a copper plate 23 is bonded to one surface of the ceramic substrate 11 using a copper member bonding paste containing Ag and a nitride-forming element to form a circuit layer 12 (circuit layer). Forming step S11). Specifically, as shown in FIG. 8, Ag and the nitride-forming element layer 25 are formed by applying a copper member bonding paste to one surface of the ceramic substrate 11 by screen printing and drying. Next, the copper plate 22 is laminated on one surface side of the ceramic substrate 11. Then, the circuit layer 12 is formed on one surface of the ceramic substrate 11 by inserting and heating the copper plate 22 and the ceramic substrate 11 in a vacuum heating furnace while being pressurized in the stacking direction.

  Next, the Ag foil 22a is laminated on one surface of the circuit layer 12, and the aluminum plate 123 is laminated on the other surface of the ceramic substrate 11 (Ag foil and aluminum plate lamination step S12). At this time, a brazing material foil 126 having a thickness of 5 to 50 μm is interposed between the ceramic substrate 11 and the aluminum plate 123. In this embodiment, the brazing material has a thickness of 14 μm. The brazing material foil 126 is an Al—Si based brazing material containing Si as a melting point lowering element.

Next, the Ag foil 22a and the aluminum plate 123 are inserted into a vacuum heating furnace in a state where pressure is applied in the stacking direction (pressure 1 to 35 kgf / cm ² ), and the Ag foil 22a and the circuit layer 12 are solid-phase diffused. Bonding is performed to form an Ag underlayer 12a for Ag sintering bonding, and a brazing filler metal foil 126 is melted and solidified on the other surface of the ceramic substrate 11 to form a metal layer 113 (Ag underlayer and metal layer formation). Step S13).
Here, in the Ag underlayer and metal layer forming step S13, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is 550 ° C. to 650 ° C., and the holding time is 30 minutes. It is set within the range of 180 minutes or less.

Next, the Ag foil 123a is laminated on the surface of the metal layer 113 opposite to the surface bonded to the ceramic substrate 11 (Ag foil lamination step S14).
Next, it is inserted into a vacuum heating furnace under pressure in the laminating direction (pressure 1 to 35 kgf / cm ² ) and heated, and the Ag foil 123a and the metal layer 113 are solid-phase diffusion bonded, and the lower surface of the metal layer 113 An Ag underlayer 113a is formed on the substrate (Ag underlayer forming step S15).
Here, in the Ag underlayer forming step S15, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is 350 ° C. to less than 567 ° C., and the holding time is 30 minutes to 180 °. It is set within the range of minutes. A more preferable heating temperature for the solid phase diffusion bonding is in a range of 5 ° C. to less than the eutectic temperature from the eutectic temperature of Ag and Al (567.0 ° C.).
In the present embodiment, the surface of the surface where the Ag foil 123a and the metal layer 113 are joined is previously removed from the surface.
As described above, the circuit board 110 according to the present embodiment is manufactured.

Next, as shown in FIG. 9, silver oxide pastes 4 and 6 to be the bonding layers 2 and 5 are applied to the surfaces of the Ag base layers 12a and 113a (silver oxide paste application step S16).
In addition, when apply | coating the silver oxide pastes 4 and 6, various means, such as a screen printing method, an offset printing method, and a photosensitive process, are employable. In this embodiment, silver oxide pastes 4 and 6 were printed by a screen printing method.

  Next, after the silver oxide pastes 4 and 6 are dried (for example, stored at room temperature in an air atmosphere for 24 hours), the semiconductor element 3 is laminated on the silver oxide paste 4, and a heat sink is placed under the silver oxide paste 6. Lamination is performed (semiconductor element and heat sink lamination step S17). In the second embodiment, similarly to the Ag underlayer forming step S15, an Ag underlayer 130a made of Ag foil is formed in advance on one surface of the heat sink 130 by solid phase diffusion bonding.

Then, the semiconductor element 3, the circuit board 110, and the heat sink 130 are stacked and placed in a heating furnace, and the silver oxide paste 4 is baked (baking step S18). At this time, the semiconductor element 3, the circuit board 110, and the heat sink 130 can be bonded more reliably by heating in a state of being pressurized in the stacking direction. In this case, the pressurizing pressure is desirably 0.5 to 10 MPa.
In this way, the circuit board 110 and the heat sink 130 are bonded via the bonding layer 5.
As described above, the semiconductor device 101 according to the present embodiment is manufactured.

According to the semiconductor device 101 and the circuit board 110 according to the second embodiment configured as described above, the same effects as the semiconductor device 1 and the circuit board 10 described in the first embodiment can be obtained.
Furthermore, in the second embodiment, since the Ag base layer 112a and the metal layer 113 are formed simultaneously, the manufacturing process can be simplified and the manufacturing cost can be reduced. In addition, since the semiconductor element 3 and the heat sink 130 are also bonded to the circuit board 110 at the same time, the manufacturing cost can be reduced.

  Further, in the Ag underlayer forming step S15, the metal layer 113 made of aluminum (Al) and the Ag foil 123a are solid-phase diffusion bonded by heating at 350 ° C. or more and less than 567 ° C. The Ag underlayer 113a can be reliably formed on the lower surface of the layer 113.

When the heating temperature at the time of solid phase diffusion bonding is 350 ° C. or higher, diffusion of Ag atoms and Al atoms is promoted, and solid phase diffusion can be sufficiently performed in a short time. Moreover, when it is less than 567 degreeC, it can suppress that the liquid phase of Ag and Al arises, a bump arises in a joining interface, or thickness changes. Therefore, the temperature range in the Ag underlayer forming step S15 is set to the above range.
Furthermore, the more preferable heating temperature of the solid phase diffusion bonding is set to a range from 5 ° C. lower than the eutectic temperature of Ag and Al (567.0 ° C.) to below the eutectic temperature, so that no liquid phase is formed. In addition to the fact that no compound of Ag and Al is produced and the bonding reliability of solid phase diffusion bonding is improved, the diffusion rate during solid phase diffusion bonding is high, and solid phase diffusion bonding can be performed in a relatively short time.

  Further, Ag base layers 113 a and 130 a formed by solid phase diffusion bonding are formed on the bonding surface between the metal layer 113 and the heat sink 130, and the bonding layer 5 made of a sintered body of the silver oxide paste 6 is interposed therebetween. Therefore, the bonding strength between the metal layer 113 and the heat sink 130 can be increased. Therefore, it is possible to improve the bonding reliability between the metal layer 113 and the heat sink 130, and heat from the circuit board 110 side can be dissipated more efficiently via the heat sink 130.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In addition, about the thing of the same structure as 1st embodiment, the same code | symbol is attached | subjected and described, and detailed description is abbreviate | omitted.

  FIG. 10 shows a semiconductor device 201 according to the second embodiment of the present invention. The semiconductor device 201 includes a circuit board 210 and a semiconductor element 3 bonded to one surface (upper surface in FIG. 10) of the circuit board 210 via a bonding layer 2.

  As shown in FIG. 10, the circuit board 210 includes a ceramic substrate 11, a circuit layer 212 disposed on one surface of the ceramic substrate 11 (upper surface in FIG. 10), and the other surface of the ceramic substrate 11 (FIG. 10 and a metal layer 213 disposed on the lower surface.

The circuit layer 212 is formed by bonding a conductive aluminum metal plate to one surface of the ceramic substrate 11. The circuit layer 212 is formed by joining aluminum rolled plates having a purity of 99.99% or more. Note that the thickness of the circuit layer 212 is set in a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.6 mm in the present embodiment.
On one surface (the upper surface in FIG. 10) of the circuit layer 212, an Ag base layer 212a made of Ag foil is formed. The Ag underlayer 212a has the same configuration as the Ag underlayer 12a described in the first embodiment, and is formed as an underlayer for Ag sintering bonding.

  The metal layer 213 is formed by bonding a conductive aluminum metal plate to the other surface of the ceramic substrate 11. Similar to the circuit layer 212, the metal layer 213 is formed by joining aluminum rolled plates having a purity of 99.99% by mass or more. Note that the thickness of the metal layer 213 is set within a range of 0.1 mm or more and 1.0 mm or less, and is set to 0.6 mm in the present embodiment.

Next, a method for manufacturing the semiconductor device 201 and the circuit board 210 according to the present embodiment will be described with reference to a flowchart shown in FIG.
First, aluminum plates 222 and 223 to be the circuit layer 212 and the metal layer 213 are laminated on one surface and the other surface of the ceramic substrate 11 with a brazing material foil 226 interposed therebetween. In this embodiment, the brazing material foil 226 is an Al—Si based brazing material containing Si which is a melting point lowering element. Then, in a state where the aluminum plates 222 and 223 and the ceramic substrate 11 are pressed in the stacking direction (pressure 1 to 35 kgf / cm ² ), the aluminum plates 222 and 223 are inserted into the heating furnace and heated, and one surface and the other of the ceramic substrate 11 are heated. A circuit layer 212 and a metal layer 213 are formed on the surface (circuit layer and metal layer forming step S21). Here, in the circuit layer and metal layer forming step S21, the heating temperature is 550 ° C. or more and 650 ° C. or less, and the heating time is 30 minutes or more and 180 minutes or less.

Next, the Ag foil 222a is laminated on one surface of the circuit layer 212 (Ag foil lamination step S22).
Next, it is inserted into a vacuum heating furnace under pressure in the laminating direction (pressure 1 to 35 kgf / cm ² ) and heated, and the Ag foil 222a and the circuit layer 212 made of aluminum are solid phase diffusion bonded, and Ag firing is performed. An Ag underlayer 212a for bonding is formed (Ag underlayer forming step S23).
Here, in the Ag underlayer forming step S23, the pressure in the vacuum heating furnace is in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa, the heating temperature is 350 ° C. to less than 567 ° C., and the holding time is 30 minutes to 180 minutes. It is set within the following range.
In the Ag underlayer forming step S23, a more preferable heating temperature for the solid phase diffusion bonding is set to a temperature that is 5 ° C. lower than the eutectic temperature of Ag and Al (567.0 ° C.) to less than the eutectic temperature.
As described above, the circuit board 210 according to the present embodiment is manufactured.

Next, the silver oxide paste 4 to be the bonding layer 2 is applied to the surface of the Ag base layer 212a (silver oxide paste application step S24).
In addition, when apply | coating the silver oxide paste 4, various means, such as a screen printing method, an offset printing method, and a photosensitive process, are employable. In the present embodiment, the silver oxide paste 4 is printed by a screen printing method.

Next, after the silver oxide paste 4 is dried (for example, stored at room temperature in an air atmosphere for 24 hours), the semiconductor element 3 is stacked on the silver oxide paste 4 (semiconductor element stacking step S25).
Then, the semiconductor element 3 and the circuit board 210 are stacked in a heating furnace, and the silver oxide paste 4 is baked (baking step S26). At this time, the semiconductor element 3 and the circuit board 210 can be bonded more reliably by heating in a state of being pressurized in the stacking direction. In this case, the pressurizing pressure is desirably 0.5 to 10 MPa.
In this way, the semiconductor element 3 and the circuit board 210 are bonded via the bonding layer 2.
As described above, the semiconductor device 201 according to the present embodiment is manufactured.

  According to the semiconductor device 201 and the circuit board 210 according to the third embodiment configured as described above, the same effects as those of the semiconductor device 1 and the circuit board 10 described in the first embodiment can be obtained.

  Further, in the Ag base layer forming step S23, the circuit layer 212 made of aluminum (Al) and the Ag foil 222a are solid-phase diffusion bonded by heating at 350 ° C. or more and less than 567 ° C. The Ag underlayer 212a can be reliably formed on the upper surface of the layer 212.

  When the heating temperature at the time of solid phase diffusion bonding is 350 ° C. or higher, diffusion of Ag atoms and Al atoms is promoted, and solid phase diffusion can be sufficiently performed in a short time. Moreover, when it is less than 567 degreeC, it can suppress that the liquid phase of Ag and Al arises, a bump arises in a joining interface, or thickness changes. Therefore, the temperature range in the Ag underlayer forming step S23 is set to the above range.

  Furthermore, since the circuit layer 212 made of aluminum having relatively low strength is formed on one surface of the ceramic substrate 11, the circuit layer 212 is deformed with low stress when a heat cycle is applied to the semiconductor device 201. It is possible to prevent the ceramic substrate 11 from being cracked.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In addition, about the thing of the same structure as 1st embodiment, the same code | symbol is attached | subjected and described, and detailed description is abbreviate | omitted.

  FIG. 13 shows a semiconductor device 301 according to the fourth embodiment of the present invention. The semiconductor device 301 includes a circuit board 310 and a semiconductor element 3 bonded to one surface (the upper surface in FIG. 13) of the circuit board 310 via a bonding layer 2.

  As shown in FIG. 13, the circuit board 310 includes a ceramic substrate 11, a circuit layer 312 disposed on one surface of the ceramic substrate 11 (upper surface in FIG. 13), and the other surface of the ceramic substrate 11 (FIG. 13, a metal layer 313 disposed on the lower surface).

The circuit layer 312 has an aluminum layer 315 formed on one surface of the ceramic substrate, and a copper layer 316 laminated on one surface of the aluminum layer 315.
The aluminum layer 315 is formed by bonding an aluminum metal plate. In this embodiment, the aluminum layer 315 is formed by joining aluminum rolled sheets having a purity of 99.99% or more.
The copper layer 316 is formed by solid phase diffusion bonding of a copper plate 326 made of an oxygen-free copper rolled plate to an aluminum layer 315.
A diffusion layer 350 is formed at the interface between the aluminum layer 315 and the copper layer 316 as shown in FIG.

  The diffusion layer 350 is formed by mutual diffusion of Al atoms in the aluminum layer 315 and Cu atoms in the copper layer 316. The diffusion layer 350 has a concentration gradient in which the concentration of aluminum atoms gradually decreases and the concentration of copper atoms increases as it goes from the aluminum layer 315 to the copper layer 316.

As shown in FIG. 14, the diffusion layer 350 is composed of an intermetallic compound composed of Al and Cu. In this embodiment, a plurality of intermetallic compounds are stacked along the bonding interface. . Here, the thickness of the diffusion layer 350 is set in the range of 1 μm to 80 μm, preferably in the range of 5 μm to 80 μm.
In the present embodiment, as shown in FIG. 14, a structure in which three types of intermetallic compounds are stacked is formed, and in order from the aluminum layer 315 side to the copper layer 316 side, a θ phase 351, a η2 phase 352, The ζ2 phase 353 is used.

In addition, oxide 354 is dispersed in layers along the bonding interface at the bonding interface between diffusion layer 350 and copper layer 316. In the present embodiment, the oxide 354 is an aluminum oxide such as alumina (Al ₂ O ₃ ). Note that the oxide 354 is dispersed at the interface between the diffusion layer 350 and the copper layer 316, and there is a region where the diffusion layer 350 and the copper layer 316 are in direct contact with each other.

  On one surface (the upper surface in FIG. 13) of the circuit layer 312, an Ag base layer 312a made of Ag foil is formed. The Ag underlayer 312a has the same configuration as the Ag underlayer 12a described in the first embodiment, and is formed as an underlayer for Ag sintering bonding.

  The metal layer 313 is formed by bonding a conductive aluminum metal plate to the other surface of the ceramic substrate 11. The metal layer 313 is formed by joining aluminum rolled plates having a purity of 99.99% by mass or more.

Next, a method for manufacturing the semiconductor device 301 and the circuit board 310 according to the present embodiment will be described with reference to a flowchart shown in FIG.
First, as shown in FIG. 16, aluminum plates 325 and 323 to be aluminum layers 315 and metal layers 313 are laminated on one surface and the other surface of the ceramic substrate 11 with a brazing material foil 226 interposed therebetween. In this embodiment, the brazing material foil 226 is an Al—Si based brazing material containing Si which is a melting point lowering element. Then, in a state where the aluminum plates 325 and 323 and the ceramic substrate 11 are pressurized in the stacking direction (pressure 1 to 35 kgf / cm ² ), the aluminum plates 325 and 323 are inserted into a heating furnace and heated, and one surface and the other of the ceramic substrate 11 are heated. An aluminum layer 315 and a metal layer 313 are formed on the surface (aluminum layer and metal layer forming step S31). In the aluminum layer and metal layer forming step S31, the heating temperature is 550 ° C. or more and 650 ° C. or less, and the heating time is 30 minutes or more and 180 minutes or less.

  Here, in this embodiment, the copper plate 326 to be the copper layer 316 and the Ag foil to be the Ag foundation layer 312a are solid-phase diffused in the same manner as the Ag foundation layer forming step S03 described in the first embodiment. It joins by joining (Ag foundation layer formation process S32).

Next, a copper plate 326 on which an Ag base layer 312a is formed is laminated on one surface of the aluminum layer 315 (copper plate lamination step S33).
Next, the ceramic substrate 11 and the copper plate 326 on which the aluminum layer 315 and the metal layer 313 are formed are inserted into a vacuum heating furnace and heated in a state of being pressurized in the stacking direction (pressure 3 to 35 kgf / cm ² ), The aluminum layer 315 and the copper plate 326 are solid phase diffusion bonded to form a copper layer 316 on one surface of the aluminum layer (copper layer forming step S34). Here, in copper layer formation process S34, heating temperature is 400 degreeC or more and 548 degrees C or less, and heating time is 15 minutes or more and 270 minutes or less.
Furthermore, a more preferable temperature of the solid phase diffusion bonding is set to a temperature lower by 5 ° C. than the eutectic temperature of Al and Cu (548.8 ° C.) and lower than the eutectic temperature.
Thus, a circuit layer having the Ag base layer 312a formed on one surface of the ceramic substrate 11 is formed.
As described above, the circuit board 310 according to the present embodiment is manufactured.

Next, the silver oxide paste 4 to be the bonding layer 2 is applied to the surface of the Ag base layer 312a (silver oxide paste application step S35).
Next, after the circuit board 310 is dried with the silver oxide paste 4 applied (for example, stored at room temperature in an air atmosphere for 24 hours), the semiconductor element 3 is stacked on the silver oxide paste 4 of the circuit board 310 ( Semiconductor element stacking step S36).

Then, the semiconductor element 3 and the circuit board 310 are stacked and placed in a heating furnace, and the silver oxide paste 4 is baked (baking step S37). At this time, the semiconductor element 3 and the circuit board 310 can be bonded more reliably by heating in a state of being pressurized in the stacking direction. In this case, the pressurizing pressure is desirably 0.5 to 10 MPa.
In this way, the semiconductor element 3 and the circuit board 310 are bonded via the bonding layer 2.
As described above, the semiconductor device 301 according to the present embodiment is manufactured.

  According to the semiconductor device 301 and the circuit board 310 according to the fourth embodiment configured as described above, the same effects as the semiconductor device 1 and the circuit board 10 described in the first embodiment can be obtained.

Further, since the circuit layer 312 has the copper layer 316, when the heat generated from the semiconductor element 3 is transferred to the circuit board 310 side, the circuit layer 312 is efficiently spread in the plane direction by the copper layer 316 of the circuit layer 312. Can be dissipated.
Further, an aluminum layer 315 having a relatively small deformation resistance is formed on one surface of the ceramic substrate 11, and when a heat cycle is applied, the difference in thermal expansion coefficient between the ceramic substrate 11 and the circuit layer 312 is caused. Since the aluminum layer 315 absorbs the thermal stress generated due to this, it is possible to suppress the generation of cracks in the ceramic substrate 11 and to obtain high reliability for bonding.
Further, since the copper layer 316 having a relatively large deformation resistance is formed on one surface of the aluminum layer 315, the deformation of the circuit layer 312 can be suppressed when a power cycle is applied. Therefore, high reliability for the power cycle can be obtained.

Further, in this embodiment, since the temperature at the time of solid phase diffusion bonding between the aluminum layer 315 and the copper plate 326 is set to 400 ° C. or more, the diffusion of Al atoms and Cu atoms is promoted, and the time is sufficient. Can be solid phase diffused. Moreover, when the temperature at the time of solid phase diffusion bonding is 548 ° C. or less, it is possible to suppress the occurrence of a liquid phase of Al and Cu, resulting in bumps at the bonding interface, and fluctuations in thickness.
Furthermore, a more preferable heating temperature for the solid phase diffusion bonding between the aluminum layer 315 and the copper plate 326 is in a range from 5 ° C. lower than the eutectic temperature of Al and Cu (548.8 ° C.) to less than the eutectic temperature. Therefore, the liquid phase is not formed, the compound of Al and Cu is not generated, the bonding reliability of the solid phase diffusion bonding is improved, and the diffusion rate at the time of the solid phase diffusion bonding is high and relatively short. Solid phase diffusion bonding can be performed in time.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.

  For example, in the above embodiment, the powder component of the copper member bonding paste contains one or more additive elements selected from In, Sn, Al, Mn, and Zn in addition to Ag and the nitride-forming element. However, it is also possible to use a paste whose powder component is made of Ag, Cu, Ti.

  Moreover, in the said embodiment, although the joining layer is made into the baking body of the silver oxide paste containing a silver oxide powder and a reducing agent, it is set as the baking body of a nano silver paste, without being limited to this. Also good. Moreover, it is also possible to comprise a joining layer with the electroconductive adhesive containing Ag powder.

In the above embodiment, the case where an Ag foil is bonded to a circuit layer and a metal layer by solid phase diffusion bonding to form an Ag underlayer has been described. However, Ag powder is bonded to a circuit layer and a metal layer by solid phase diffusion bonding. By doing so, an Ag underlayer may be formed.
For example, a silver paste mixed with a solvent and silver powder is printed on the circuit layer and metal layer, dried thoroughly, and pressed in the stacking direction with a ceramic such as aluminum nitride that does not react with silver even at high temperatures (for example, applied pressure) The Ag underlayer can also be obtained by heating at 1 to 35 kgf / cm 2).

  In the above embodiment, the aluminum layer, the circuit layer, and the metal layer formed on one surface and the other surface of the ceramic substrate have been described as a rolled plate of pure aluminum having a purity of 99.99%. However, it may be 99% pure aluminum (2N aluminum), aluminum alloy, or the like.

In the above embodiment, the case where the copper layer and the circuit layer are made of an oxygen-free copper plate has been described. However, the present invention is not limited to this, and other copper plates such as pure copper and copper alloy are used. May be.
In the above embodiment, the case where the circuit layer is formed by solid phase diffusion bonding of the aluminum layer and the copper layer has been described. However, the circuit layer may be formed of a clad material of the copper layer and the aluminum layer.
Further, it is described that uses a ceramic substrate made of AlN as an insulating layer, is not limited thereto, it may be used a ceramic substrate made of Si ₃ N ₄ or Al ₂ O _3, or the like, insulating The insulating layer may be made of resin.

  Moreover, although the said embodiment demonstrated the case where the metal layer was comprised with the pure aluminum of purity 99.99%, it is not limited to this, A metal layer is arrange | positioned at the other surface of a ceramic substrate. The aluminum layer and a copper layer laminated on the surface of the aluminum layer opposite to the surface on which the ceramic substrate is disposed may be used.

Below, the result of the confirmation experiment performed in order to confirm the effect of this invention is demonstrated.
(Invention Examples 1 to 4)
On the metal member shown in Table 1, an Ag underlayer was formed by solid phase diffusion bonding of 15 mm × 15 mm × 0.01 mmt Ag foil. The solid phase diffusion bonding was performed under the conditions shown in Table 1 with the pressure in the vacuum heating furnace set in the range of 10 ⁻⁶ Pa to 10 ⁻³ Pa.

  Then, a silver oxide paste is applied on the Ag underlayer (application thickness: 50 μm), a 2.5 mm × 2.5 mm × 0.2 mmt Si plate is further disposed, and the silver oxide paste is fired to form a bonding layer. Then, the metal member and the Si plate were joined. The Si plate was joined after the Au film was formed.

Here, as the silver oxide paste, commercially available silver oxide powder (manufactured by Wako Pure Chemical Industries, Ltd.), myristyl alcohol as the reducing agent, and 2,2,4-trimethyl-1,3-pentanediol mono (2 -Methyl propanoate), silver oxide powder; 80% by mass, reducing agent (myristyl alcohol); 10% by mass, solvent (2,2,4-trimethyl-1,3-pentanediol mono (2) -Methylpropanoate)); The remainder was used in the ratio of silver oxide paste mixed.
As firing conditions, the firing temperature was 300 ° C., the firing time was 10 minutes, and the pressurizing pressure was 5 MPa. Inventive Examples 1 and 2 fired silver oxide paste in a vacuum atmosphere, and Inventive Examples 3 and 4 fired silver oxide paste in an air atmosphere.
As described above, joined bodies of Examples 1 to 4 of the present invention were produced.

(Comparative Examples 1 and 2)
Comparative examples 1 and 2 were prepared in the same manner as in inventive examples 1 and 2 except that no Ag underlayer was formed on the metal member. That is, the joined body of Comparative Examples 1 and 2 was manufactured by joining the metal member and the Si plate with the joining layer obtained by firing the silver oxide paste without forming the Ag underlayer on the metal member. In Comparative Examples 1 and 2, the silver oxide paste was baked in a vacuum atmosphere.

(Comparative Examples 3 and 4)
Comparative examples 3 and 4 were produced in the same manner as in inventive examples 1 and 2, except that an Ag underlayer was formed on the metal member by plating. That is, after the Ag underlayer was formed by plating on the metal member, the metal member and the Si plate were joined by the joining layer obtained by firing the silver oxide paste, thereby producing the joined bodies of Comparative Examples 3 and 4. In Comparative Examples 3 and 4, the silver oxide paste was baked in a vacuum atmosphere.

  In the joined body obtained as described above, using a cross section polisher (SM-09010, manufactured by JEOL Ltd.), ion acceleration voltage: 5 kV, processing time: 14 hours, protrusion amount from shielding plate: 100 μm Using a scanning electron microscope (ULTRA55 manufactured by Carl Zeiss NTS), the ion-etched cross section was subjected to In-Lens image and ESB image photography and EDS analysis at acceleration voltage: 1 kV, WD: 2.5 mm, and solid phase diffusion. The presence or absence of was investigated.

  Moreover, in the obtained joined body, shear strength (shear strength) was measured by a shear test. The metal member is fixed horizontally with the Si plate facing up, the Si plate is pressed horizontally from the side with a shear tool, and the strength and position of the fracture when the bond between the metal member and the Si plate is broken (destruction mode) )It was confirmed. In addition, the intensity | strength was made into the average value after implementing the shear strength test 3 times. The results are shown in Table 1.

In the inventive examples 1 to 4 in which the Ag base layer is solid phase diffusion bonded to the metal member, the shear strength is 37 MPa or more, the bonding strength between the metal member and the Si plate is high, and the breakdown occurs in the Ag bonding layer. Therefore, it was confirmed that sufficient bonding strength was ensured.
In Comparative Examples 1 and 2 in which the Ag underlayer was not formed on the metal member, the shear strength was as low as 5 MPa or less, and the fracture occurred at the interface between the Ag bonding layer and the metal member.
In Comparative Examples 3 and 4 in which the Ag base layer was formed on the metal member by plating, the shear strength was 8 MPa or less, and the joint strength was lower than that of the inventive example.

1, 101, 201, 301 Semiconductor device 2 Bonding layer 3 Semiconductor element (other member)
4 Oxide paste (bonding material)
10, 110, 210, 310 Circuit board (metal composite)
11 Ceramic substrate (insulating layer)
12, 212, 312 Circuit layer (metal member)
12a, 113a, 212a, 312a Ag base layer 113, 213, 313 Metal layer (metal member)
22a, 123a, 222a Ag foil

Claims (6)

A metal composite comprising an insulating layer and a metal member disposed on one surface or the other surface of the insulating layer,
The metal member is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer,
An Ag underlayer for Ag sintering bonding is formed on the surface of the metal member opposite to the surface on which the insulating layer is disposed, and the Ag underlayer is made of Ag foil.
An element of the metal member is diffused in the Ag base layer, and Ag of the Ag base layer is diffused in the metal member. A circuit layer made of the metal composite according to claim 1 and made of the metal member disposed on one surface of the insulating layer, wherein the circuit layer is made of copper, aluminum, or an aluminum layer and a copper layer. Made of
An Ag underlayer for Ag sintering bonding is formed on the surface of the circuit layer opposite to the surface on which the insulating layer is disposed, and the Ag underlayer is made of Ag foil.
The circuit board, wherein the element of the circuit layer is diffused in the Ag underlayer, and Ag of the Ag underlayer is diffused in the circuit layer . A circuit layer made of the metal composite according to claim 1 and disposed on one surface of the insulating layer, and a metal layer made of the metal member disposed on the other surface of the insulating layer. Provided, the metal layer is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer,
An Ag underlayer for Ag sintering bonding is formed on the surface of the metal layer opposite to the surface on which the insulating layer is disposed, and the Ag underlayer is composed of Ag foil,
A circuit board , wherein an element of the metal layer is diffused in the Ag underlayer, and Ag of the Ag underlayer is diffused in the metal layer . A circuit layer made of the metal composite according to claim 1 and disposed on one surface of the insulating layer, and a metal layer made of the metal member disposed on the other surface of the insulating layer. The circuit layer is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer,
An Ag underlayer for Ag sintering bonding is formed on the surface of the circuit layer opposite to the surface on which the insulating layer is disposed, and the Ag underlayer is made of Ag foil.
The circuit board, wherein the element of the circuit layer is diffused in the Ag underlayer, and Ag of the Ag underlayer is diffused in the circuit layer . A circuit board according to any one of claims 2 to 4, and a semiconductor element bonded to the Ag underlayer,
A semiconductor device, wherein the Ag base layer and the semiconductor element are bonded by a bonding layer made of a sintered body of a bonding material containing at least one or both of Ag particles and silver oxide particles and an organic substance. A method for producing a metal composite in which a metal member is disposed on one surface or the other surface of an insulating layer,
The metal member is made of copper, aluminum, or a laminate of an aluminum layer and a copper layer,
Disposing the metal member on one surface or the other surface of the insulating layer;
A step of disposing Ag foil on the surface of the metal member opposite to the surface on which the insulating layer is disposed;
And a step of solid-phase diffusion bonding the metal member and the Ag foil to form an Ag underlayer for Ag sintering bonding.

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