JPH04238877A - Jointed form made up of aln member and cu member and production thereof - Google Patents

Abstract

PURPOSE:To obtain an assured, highly reliable jointed form by putting a Zr-Ti- Cu-based intermediate layer between an AlN and Cu members followed by heating and jointing. CONSTITUTION:The objective jointed form for use in electronic circuits can be obtained by putting (A) an intermediate layer comprising (1) 10-90wt.% of Zr, (2) 10-90wt.% of Ti and (3) the rest of Cu between an AlN and Cu members followed by heating. The intermediate layer may be further incorporated with <=30wt.% of Ni.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applied to ceramic substrates for forming electronic circuits such as power semiconductor modules.
The present invention relates to a joined body of an IN member and a Cu member and a method for manufacturing the same.

0002

[Prior Art] In electronic circuits, ceramics serving as substrates are usually joined to circuits and elements such as conductors for assembly, but in any case, the joining of ceramics and metals is becomes a problem. Many studies have been conducted on the bonding of ceramics and metals using conventional technology, but the key points are: ■ ensuring wetting at the bonding interface, ■ controlling the layer that forms at the bonding interface, and ■ preventing cracking due to thermal stress. prevention. Oxide ceramics (
For example, in the case of materials containing Al2O3 as the main component, these problems have been largely solved. However, nitride-based ceramics have problems in that it is not easy to check wetting at the bonding interface with metal, and the difference in thermal expansion with metal is large, making them more likely to crack due to thermal stress.

On the other hand, as an electronic circuit ceramic substrate,
In order to increase the power consumption, conventionally used Al2O
It is desired to develop a substrate using AlN (nitride-based) material, which has superior heat dissipation efficiency compared to 3-based materials. In particular, there is a strong demand for improvement in heat dissipation efficiency in large electronic circuit devices. As a bonding technique for bonding an AlN substrate and a circuit made of Cu, a method of interposing a Ti layer between AlN and Cu and bonding by heating is disclosed in Japanese Patent Laid-Open No. 60-1.
It is disclosed in Japanese Patent No. 77634. In this method, T
It utilizes the wetting of i-Cu eutectic and AlN, and T
Examples of intervening means include (i) interposition of Ti foil, (ii) deposition of Ti by vapor deposition, plating, and sputtering. Separately from this, Japanese Patent Application Laid-Open No. 60-32343 discloses a substrate provided with an alloy layer of an active metal such as Zr and copper in addition to the above-mentioned Ti.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned known method, it is necessary to interpose Ti between the AlN substrate and the Cu conductor circuit and heat it to about 1000°C for bonding. The stress is large, and cracks may occur depending on variations in the control of the thickness of the reaction layer at the bonding interface. Furthermore, deformation due to thermal strain also increases. The detailed explanations in the above-mentioned Japanese Patent Application Laid-Open Nos. 60-177634 and 32343/1987 state that heating at about 880 to 1082°C is sufficient. Regarding the above point, the inventors conducted additional tests and found that bonding is not possible at temperatures around 880°C, and bonding is not possible at temperatures around 1000°C (specifically, 990°C), as shown in the examples in the publication. It was confirmed that this is not possible. Further, with the technique disclosed in the publication, it is impossible to bond in a short time of about 10 minutes.

[0005] Problems with the prior art described above include, for example, the following points. (1) AlN bonded to Cu conductor circuit In order to ensure wetting of the substrate in a short time, heating bonding at approximately 1000° C. is required. As a result, the thermal stress at the bonding interface becomes large, making it easy for cracks to occur at the bonding interface (the tolerance limit for the reaction layer thickness is small), and furthermore, deformation due to thermal strain is large. (2) The method of intervening Ti necessary to form a eutectic reaction layer is inefficient. The present invention solves the problems in the prior art as described above, and improves the quality of aluminum used in electronic circuits.
The object of the present invention is to provide a reliable joined body of an N member and a Cu member and a method for manufacturing the same.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted intensive research and have found that when bonding a circuit pattern Cu member to an AlN substrate as an electronic circuit ceramics substrate, it is possible to It was discovered that a low-temperature ternary eutectic of Cu-Ti-Zr was formed by interposing a composite of Ti and Zr therebetween, thereby enabling bonding at low temperatures, and the present invention was completed. Furthermore, Ti, Zr
When Ni is added to the reaction layer, the thermal expansion coefficient of the reaction layer becomes smaller (
It was found that it is effective in reducing thermal stress. That is, the present invention provides A for electronic circuits.
A joined body of an IN member and a Cu member, the AlN
AlN for electronic circuits, characterized in that an intermediate layer containing Zr: 10-90% and Ti: 10-90% by weight % and the balance consisting of Cu is interposed between a member and a Cu member.
This is a joined body of a member and a Cu member.

[0007] The intermediate layer further contains Ni: 30% by weight.
May contain the following: From another aspect, the present invention provides a foil body substantially made of Ti and a Z
After overlapping the foil bodies made of r, they are rolled and joined, and further,
This is a method for manufacturing a joined body of an AlN member and a Cu member in an electronic circuit, characterized in that an AlN member is stacked on the foil side and bonded by heat. Cu from the Cu member and Ti and Zr from the foil are mutually diffused to form a Cu-Ti-Zr ternary eutectic intermediate layer. The foil body made of Ti and Zr
Further, one or more foil bodies consisting of a foil body consisting of Cu and a foil body consisting of Ni are further stacked on the foil body consisting of Al.
The N member and the Cu member may be joined by rolling. The stacking order of these foils is not particularly limited, but Ni
It is preferable to laminate the foil, Cu foil, Zr foil, and Ti foil in this order.

[0008]

[Operation] The reasons for limiting the conditions such as the constituent materials and manufacturing method of the joined body in the present invention are as follows. (1) Cu is used because it is optimal as a material for conductors for circuit boards in terms of economy, conductivity, workability, etc. (2) AlN is used as a substrate material because it has superior thermal conductivity and strength compared to Al2O3. (3) The thickness of the intermediate layer is determined when Cu foil or Ni foil is used.
), the total thickness of the foil material layer after being rolled and bonded to the Cu member for the circuit is preferably 5 μm or more.
It should be less than μm. The lower limit of the thickness was determined as the possible limit to ensure wettability with AlN, and the upper limit was determined as the range necessary to prevent cracking of the formed reaction layer.

(4) The composition (weight %) of the intermediate layer is Ti.
: 10 to 90, Zr: 10 to 90, and the balance is Cu, and if necessary, Ni: 30% or less. Due to heating during bonding, Ti and Zr react with Cu of the Cu member or with previously bonded Cu to form a low-temperature eutectic and contribute to wetting with AlN. If the amounts of Zr and Ti are within the above composition range, the melting temperature of the intermediate layer will be around 850° C., making low-temperature bonding possible. Outside this composition range (outside the upper and lower limits), the melting temperature of both intermediate layers becomes high, making it impossible to bond at low temperatures, which is an advantage of the present invention. Eutectic is generated when Ti and Zr, which are laminated and integrated into a Cu bonded body in the form of a foil, react with the Cu of the Cu bonded body, but if the Cu foil material is also included in the foil material layer, this reaction can be suppressed. The addition of Cu to the foil material layer can be said to be more effective. The eutectic that contributed to the bonding of the AlN member and the Cu member remains as a bonding intermediate layer. In order to reduce the thermal expansion coefficient of this bonding intermediate layer, Ni
can be added. However, excessive addition of Ni
The content is set to 30% or less because it causes an increase in the melting point of the eutectic.

(5) Note that rolling to join the foil bodies after stacking them may be either cold rolling or warm rolling (at 200° C. or lower). (6) The bonding temperature is higher than the melting point of Cu-Ti-Zr eutectic (
(approximately 850°C), preferably 950°C or less. If the temperature is below the melting point of the eutectic, wettability with AlN is not ensured. On the other hand, if the temperature exceeds 950° C., the thermal stress increases and there is a risk that cracks will occur in the bonding layer. In addition, the above
An inert gas atmosphere, a vacuum atmosphere, or the like is used as the bonding atmosphere for bonding the AlN member and the Cu member, and the object to be processed is heated in this atmosphere. According to the present invention, even if the wiring pattern is complicated, the circuit wiring pattern can be cut out from a conductive Cu board to which a foil material is bonded, placed on an AlN substrate, and heated in the atmosphere. Wiring and board can be easily joined.

[0011]

EXAMPLES The present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto. Figure 1 (a
), Ti, Zr, Ni, and C are placed on a Cu plate for conductors.
A Cu member bonded to the foil material layer was manufactured by overlapping and cold-rolling the u foils to produce a Cu member bonded to the foil material layer (Fig.
). By changing the initial thickness of each foil material and the rolling reduction ratio during rolling joining, it is possible to create a bonded body of Cu plate and foil material with different compositions and thicknesses of the foil material layer bonded to the Cu plate. . A 0.3 x 40 x 40 mm plate was cut out from this bonded body and placed on a 1 x 50 x 50 mm AlN substrate.
Arranged so that the foil material layer side is in contact with AlN, and weighs 0.1 kg.
A pressurizing force of f/mm2 was applied, the pieces were placed in a furnace in an Ar atmosphere, heated, and bonded as shown in FIG. 2. After joining,
An intermediate layer is formed between each of the AlN and Cu members. The bonding strength was evaluated by soldering a 1φmm copper wire to the corner of the bonded body as shown in FIG. 3, and performing a peel test of the bonded portion by pulling the copper wire upward. The results are shown in Table 1.

0012

[Table 1]

As shown in A1 to A3 of the examples of the present invention, Ti,
Those bonded with a layer containing an appropriate amount of Zr are
Good bonding strength was obtained at a relatively low temperature of 850°C. In addition, the bonding time is shortened by adding Cu (A1
A4 takes a shorter time compared to ~3), and Ni
No cracks will occur even if the foil material layer is made thicker by adding it (A5
) was confirmed. On the other hand, in the comparative example, with no foil material layer (B1) and with an insufficient thickness of the foil material layer (B5), sufficient wetting was not ensured, and with Ti only added (B2), 85%
Bonding was not possible at 0°C. Also, if the thickness is too large even if a foil material layer with appropriate components is used for bonding (B4)
Even though wetting was ensured, thermal stress increased and cracks occurred. From the above results, according to the present invention, AlN
It was confirmed that stable bonding between a substrate made of Cu and a circuit wiring made of Cu can be performed at low temperatures.

[0014]

[Effects of the Invention] Since the present invention is constructed as described above, it is possible to use Al for highly reliable substrates in electronic circuits.
A bonded body of an N member and a Cu member, which is a conductor, and a method for manufacturing the same have been established, which makes it possible to provide high-performance products and is extremely useful industrially.

[Brief explanation of the drawing]

[Fig. 1] Figs. 1(a) and 1(b) show the circuit Cu plate used in the present invention and the foil body before (a) and after (b) rolling bonding, respectively.
) is an explanatory diagram.

FIG. 2 is a sectional view of a joined body of an AlN substrate and a Cu board for circuits.

FIG. 3 is a perspective view when performing a strength test of a joint.

Claims (4)

[Claims] 1. A joined body of an AlN member and a Cu member for an electronic circuit, wherein the AlN member and the Cu member contain Zr: 10 to 90% and Ti: 10 to 90% by weight.
A joined body of an AlN member and a Cu member for an electronic circuit, characterized by interposing an intermediate layer containing % of AlN and the remainder consisting of Cu. 2. The intermediate layer further comprises Ni:3 by weight%.
The joined body of the AlN member and Cu member according to claim 1, which contains 0% or less. 3. A foil body made essentially of Ti and a foil body made of Zr are stacked on the surface of the Cu member, and then rolled and bonded.Furthermore, an AlN member is stacked on the foil body side and heat bonded. Features of AlN members for electronic circuits and C
A method for manufacturing a joined body of u members. 4. The foil body made of Ti and the foil body made of Zr are further laminated with one or more foil bodies consisting of a foil body substantially made of Cu and/or a foil body made of Ni, and then rolled and bonded. AlN member for electronic circuit according to claim 3 and C
A method for manufacturing a joined body of u members.