JP2000323618A - Copper circuit clad substrate and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copper circuit clad substrate with high adhesion in which a damage or warpage due to thermal stress on the substrate does not occur, is applicable to a high power module, and has excellent reliability when mounted on or used for a ceramic base material such as a semiconductor element or a lead frame. SOLUTION: This substrate consists of a high melting point metal layer 2 provided on one or both surfaces a metal intermediate layer 3 containing at least one kind of nickel or copper as a main component and a conductive layer 4 containing copper as a main component, which are orderly provided on one or both surfaces of a ceramic base material 1. The length and width of the metal intermediate layer 3 in the planar direction is small than those of the high melting point metal layer 2 by 0.05 mm or more. An outer peripheral edge of the metal intermediate layer 3 is positioned inside the outer peripheral edge of the high melting point metal layer 2, and the peripheral edge of the conductive layer 4 is positioned on or inside the peripheral edge of the metal intermediate layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper circuit bonding substrate for a semiconductor device having a conductor layer mainly composed of copper on a ceramic substrate.

[0002]

2. Description of the Related Art Conventionally, as an insulating base material used for a semiconductor device, an aluminum oxide-based ceramic (Al ₂
Ceramics containing O ₃ as a main component (hereinafter referred to as alumina), aluminum nitride-based ceramics (ceramics containing AlN as a main component, hereinafter referred to as aluminum nitride), and silicon nitride-based ceramics (ceramics containing Si ₃ N ₄ as a main component) , Silicon nitride). On these base materials, a metallized circuit containing tungsten (W) or molybdenum (Mo) as a main component or a circuit containing copper (Cu) as a main component is formed.
It has been used as a circuit board for C.

[0003] Each of the above-mentioned ceramics used for the insulating base material has excellent electrical insulation properties and mechanical strength, and also has high thermal conductivity. Its thermal conductivity is a commercial product, which is about 17, 60, 170 W / mK in the order of alumina, silicon nitride, and aluminum nitride. Among them, aluminum nitride has recently been spotlighted as a substrate for circuit boards because aluminum nitride has excellent thermal conductivity of more than 100 W / m · K while having almost the same electrical insulation properties as alumina and silicon nitride. Material.

[0004] In view of the coefficient of thermal expansion of these ceramics, aluminum nitride has a temperature from room temperature to a silver brazing temperature (about 8 ° C).
Since the average coefficient of thermal expansion up to 00 ° C.) is as small as 5.5 × 10 ⁻⁶ / ° C., the bonding consistency with a semiconductor chip of Si (thermal expansion coefficient 4.0 × 10 ⁻⁶ / ° C.) is good. Silicon nitride has a lower thermal conductivity than aluminum nitride, but its thermal expansion coefficient is almost the same as aluminum nitride, and it has higher mechanical strength than aluminum nitride. By doing so, thermal resistance has been suppressed, and it has begun to be used as a substrate for circuit boards.

However, since the coefficient of thermal expansion of each of the above ceramics, including aluminum nitride, is small, the matching with the conductor circuit formed on the ceramic base material is not satisfactory. In particular, copper (coefficient of thermal expansion 16.7 × 10 ⁻⁶ /
When a conductor circuit whose main component is (.degree. C.) is formed on a ceramic base material, the matching of the thermal expansion coefficients of the two is very poor.
For this reason, due to thermal stress at the bonding interface that occurs in the bonding stage of the conductor circuit and the practical stage actually used as a substrate,
The ceramic substrate was easily broken or deformed. Therefore, conventionally, the bonding between the ceramic substrate and the copper circuit has been usually performed by interposing various intervening layers for relaxing thermal stress between them.

[0006] In general, with regard to the joining of a nitride ceramic and a metal, it is known that various intervening layers are formed between them. For example, in Japanese Patent Publication No. 2-34908,
There is described a bonding mode in which a layer made of a low elastic modulus metal and / or a metal having ductility, a brittle material layer, and a low thermal expansion material layer are interposed in this order from the ceramic side. However, this type of bonding with multiple intervening layers tends to lower the thermal conductivity of each intervening layer, so that there is a practical limit to application to a heat dissipation substrate.

Therefore, usually, when joining an aluminum nitride base material to a metal member such as a lead frame or an envelope,
A metallized layer of W, Mo, or the like is provided on the surface of an aluminum nitride base material, and bonding is performed by silver brazing through the metallized layer. For example, in Japanese Patent Application Laid-Open No. 63-289950, oxygen-free copper having high thermal conductivity and high thermal buffering property is used as a lead frame for a W metallized layer on aluminum nitride (see FIGS. 1 and 2 of the same publication). Forming a Ni layer for improving wettability on a W metallized layer on aluminum nitride and an oxygen-free copper lead frame in some cases;
These are joined by silver brazing. According to the method of joining the oxygen-free copper lead frame via the W metallization layer, the thermal stress at the joint interface due to heating during brazing is greatly reduced as compared with a normal lead frame such as Kovar. There is no reduction in strength.

However, since oxygen-free copper is soft, there is a problem that it is difficult to maintain the shape as a lead frame. Further, when the copper-based member is joined to the aluminum nitride base material via the silver brazing layer as described above, a thermal stress effect at the time of brazing due to a difference in thermal expansion between the silver brazing and the aluminum nitride is large. Breakage deformation such as cracking and warping is likely to occur in the aluminum nitride base material afterwards. For this reason, there is a problem that a special and expensive silver brazing material that is rich in silver and soft is used to reduce the stress at the time of cooling, and strict control in a small amount area is required to make the silver brazing layer thinner. There is.

For this reason, a method of directly joining a metal member of a conductor to an aluminum nitride base material has been studied as an alternative to a brazing material layer such as silver brazing. One of them is a so-called DBC (direct bonding copper) method. For example, Japanese Unexamined Patent Publication No. 59-40404 discloses that a bonding layer made of an oxide of aluminum, a rare earth element, or an alkaline earth element, which is a sintering aid for the same sintered body, is formed on the surface of an aluminum nitride substrate or simply nitrided. An oxide layer of aluminum itself is formed, and the other metal member contains a small amount of the same kind of oxide binder (including the case of only oxygen), or these binding layers are formed on the surface in advance and nitrided. There is disclosed a method of directly bonding a bonding layer or an oxide layer on an aluminum substrate and the metal member or the bonding layer thereof by utilizing the affinity between the two. For example, when the metal member is copper, heat treatment is performed at a temperature lower than the melting point of copper and equal to or higher than the eutectic temperature of copper oxide and copper using the copper oxide on the surface, and an oxide layer is formed on the surface. With the aluminum nitride formed.

A similar method is also disclosed in Japanese Patent Application Laid-Open No. Sho 60-32343. Specifically, a thin active metal (Ti, Zr, Hf, etc.) is provided between an aluminum nitride substrate and a copper radiator plate.
A joining method in which a copper alloy eutectic layer containing is interposed is introduced. Further, the above-mentioned DBC method is reported in "Electronic Ceramics", November 1988, pp. 17-21. According to this, first, a thin aluminum oxide layer up to several μm is formed on the surface of the aluminum nitride substrate,
This through Cu ₂ O-Al ₂ O ₃ eutectic doing bonding with copper.

[0011] However, the bonding of copper and ceramic using the eutectic region of copper oxide and copper as described above, as shown in FIG. Unless the thickness of the layer is controlled in a narrow range, the variation in bonding strength increases. In addition, even in this method, basically, due to the difference in thermal expansion coefficient between aluminum nitride and aluminum oxide between the copper members, breakage deformation such as cracking or warpage of the substrate is likely to occur. Furthermore,
For copper-copper oxide eutectic bonding at around 1000 ° C., it is necessary to create a special oxygen partial pressure atmosphere, and this oxidizes the copper member surface. Extra work such as polishing the surface is required. In addition, when the copper member is mounted on the aluminum nitride base material, it takes time and effort to position the non-mounting portion and to form a boundary with the melting portion to be mounted with good reproducibility.

Incidentally, the bonding method using an active metal described in the above-mentioned Japanese Patent Application Laid-Open No. Sho 60-32343 requires an expensive active metal brazing material, and a high degree of vacuum of 10 ^-4 Torr or less is required at the time of brazing. Become. In addition, when brazing in nitrogen, it is often necessary to adjust a special metal brazing material such as adding a large amount of Ti to the brazing material in advance. Furthermore, when an active metal brazing material is used, voids are not generated at the interface with the ceramic substrate, so that the active metal brazing material is easily broken, and the brazing material may increase thermal resistance.

[0013]

As described above, in the conventional method of directly joining a copper member and a ceramic substrate with an oxide layer or an activated metal brazing agent layer interposed therebetween, the difference in thermal expansion between copper and ceramic is reduced. For this reason, there has been a defect that the ceramic substrate has cracks and warpages due to thermal stress generated at the time of manufacturing and use, and peeling of the copper member is caused, and the reliability is extremely low. Also, in the case of joining by copper eutectic, it is necessary to form a groove in the surface of the copper member to introduce an oxidizing atmosphere into the joining interface. Therefore, a space is generated between the ceramic base member and the copper member, which causes a discharge, a variation in bonding strength is likely to be large, and a bonding method is complicated, resulting in an increase in cost.

The present inventors have already disclosed in JP-A-9-27516.
No. 6 solves the above-mentioned conventional problems, prevents breakage and deformation of the ceramic substrate caused by thermal stress during joining and use of the conductor layer, and discharge generated in the space between the conductor layer and the ceramic substrate. It is possible to avoid the phenomenon,
We have proposed a copper circuit bonding board that can reduce costs and provide stable bonding strength. That is, this copper circuit bonding board is composed of a refractory metal layer mainly composed of a refractory metal and at least one of nickel, copper and iron having a melting point of 1000 ° C. or less on a ceramic substrate in this order from the substrate side. And a metal intervening layer comprising a main component, and a conductor layer mainly composed of copper is joined to the metal intervening layer.

In the above-described copper circuit bonding board, the refractory metal layer functions to relieve thermal stress generated by a difference in thermal expansion coefficient between the ceramic base and the copper-based conductor layer. The metal intervening layer has a function of improving wettability at the time of joining between the high melting point metal layer and the conductor layer. This joint structure is characterized in that a brazing material layer such as ordinary silver brazing or solder is not included in the joining portion, and cracking of the ceramic base and warping of the substrate, which were likely to occur when a brazing material layer was included in the past. It is effective for prevention. Further, a eutectic phase containing an active metal or Cu ₂ O
-Al ₂ O ₃ problems arising in the case of DBC method, which is joined by eutectic layer was also substantially eliminated.

Further, the present inventors have made in the above application that
The joint structure where the length and width of the conductor layer in the plane direction at the joint interface between the conductor layer and the metal interposition layer are shorter than that of the metal interposition layer, and the angle between the side surface of the conductor layer and the top surface of the metal interposition layer A joint structure at 80 degrees or less was also proposed. With such a bonding structure, it is possible to avoid a discharge phenomenon occurring between the ceramic base material and the conductor layer when the conductor layer is energized.

However, even the above-mentioned copper circuit bonding board proposed by the present inventors has the harshest operating environment and large board size, and is used for applications such as machine tools, electric vehicles and electric railways. Since high-power modules (high-power modules) do not always have sufficient stress relaxation,
There is a need for a copper circuit bonding substrate having higher reliability.

In view of the above situation, the present invention further improves the conductor circuit bonding board proposed in Japanese Patent Application Laid-Open No. 9-275166 to improve the bonding strength of each bonding portion, and particularly to the reliability in a thermal cycle. It is an object of the present invention to provide a copper circuit bonding substrate which is extremely high and is useful for a high power module.

[0019]

Means for Solving the Problems To achieve the above object, a copper circuit bonding board provided by the present invention is provided with a ceramic base and one side or both sides of the ceramic base in order from the base side. A copper circuit bonding substrate comprising a high melting point metal layer mainly composed of a high melting point metal, at least one metal intervening layer containing at least one of nickel and copper as a main component, and a conductor layer mainly containing copper. Wherein the length and width of the intervening metal layer at the joint interface between the refractory metal layer and the intervening metal layer are 0.05 mm or more shorter than those of the refractory metal layer in the planar direction, and The edge is inside the outer peripheral edge of the refractory metal layer, and the outer peripheral edge of the conductor layer is on or inside the outer peripheral edge of the metal intervening layer.

In the above-mentioned copper circuit bonding board of the present invention,
The metal intervening layer is preferably made of an alloy layer containing at least two of copper, nickel and phosphorus, and an outer layer mainly composed of Ni is formed on the outermost surface or the outermost surface and side surfaces of the conductor layer. Is more preferable. In this case, on the exposed outer surface of the ceramic base material and the high melting point metal layer, except for the main surface on which the metal intervening layer was formed,
No outer layer mainly composed of Ni is formed.

The copper circuit bonding board of the present invention has high reliability in a cooling / heating cycle and is suitable as a board for a semiconductor device represented by a high power module. Furthermore,
A semiconductor device such as a high power module can be provided by die bonding a semiconductor element to the conductor layer.

One of the methods for manufacturing a copper circuit bonding board according to the present invention includes a step of applying a paste containing a high melting point metal on a ceramic base material made of a sintered body and firing it to form a high melting point metal layer. A length and a width of the conductor layer mainly composed of copper are shorter by 0.05 mm or more than those of the refractory metal layer in a plane direction on a bonding surface side of the refractory metal layer with at least one of nickel and copper. Forming a metal intervening layer containing, as a main component, a ceramic base provided with the high melting point metal layer via the metal intervening layer and the conductor layer; Joining the ceramic substrate provided with the high melting point metal layer and the conductor layer at a temperature lower than the melting point of the conductor layer via the metal intervening layer so as to be inside the outer peripheral edge of the conductor layer. It is characterized by the following.

Further, another method of manufacturing a copper circuit bonding substrate according to the present invention is a method of manufacturing a copper circuit bonding substrate having a conductor layer mainly composed of copper on a ceramic base, wherein the method comprises the steps of: A step of applying a paste containing a high melting point metal thereon and firing it to obtain a ceramic base and simultaneously forming a high melting point metal layer on the ceramic base; and forming the high melting point metal of a conductor layer mainly composed of copper. On the bonding surface side with the layer, the length and width in the planar direction are 0.05 times higher than those of the refractory metal layer.
mm or more, a step of forming a metal intervening layer containing at least one of nickel and copper as a main component, and a step of forming a metal layer between the ceramic base and the conductor layer provided with the refractory metal layer via the metal intervening layer. The ceramic base and the conductor layer provided with the refractory metal layer via the metal interposition layer so that the outer peripheral edge of the intervening layer is inside the outer peripheral edge of the refractory metal layer. Bonding at a temperature lower than the melting point.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION In the copper circuit bonding substrate of the present invention, the length and width of the metal intervening layer in the plane direction at the bonding interface between the metal intervening layer and the high melting point metal layer are larger than those of the high melting point metal layer.
The outer peripheral edge of the metal intervening layer is located inside the outer peripheral edge of the high melting point metal layer. Specifically, as shown in FIG. 1, the main surface of the metal intervening layer 3 that is directly bonded to the high-melting-point gold layer 2 is formed immediately below the main surface in the plane length and width direction. It is shorter than that of the refractory metal layer 2 by at least 0.05 mm, preferably in the range of 0.05 to 1 mm. Also,
When viewed from a direction perpendicular to the main surface of the metal intervening layer 3, the outer peripheral edge of the metal intervening layer 3 is arranged so as not to protrude from the outer peripheral edge of the refractory metal layer 2 immediately below.

In the conventional substrate of this type, as shown in FIG. 2, the main surface of the metal interposed layer 13 which is directly bonded to the refractory metal layer 12 is the main surface of the refractory metal layer 12 immediately below it. And the outer peripheral dimensions were the same, and the outer peripheral edges of both coincided. However, when the conductor layer 14 and the refractory metal layer 12 are actually joined by making the metal intervening layer 13 into a liquid phase,
As shown in FIG. 4, it was confirmed that the intervening metal layer 13 in the liquid phase flows toward the outer peripheral end of the high melting point metal layer 12 and accumulates at the outer peripheral end of the high melting point metal layer 12 due to surface tension to form 13 a. Was done. As a result, in the conventional substrate, the thermal stress generated due to the difference in the thermal expansion coefficient between the conductor layer 14 and the ceramic base material 11 accumulates and concentrates on the outer peripheral edge of the high melting point metal layer 12 on which the 13a is formed. It has been found that the substrate 11 is easily broken.

On the other hand, in the case of the present invention, since the outer peripheral edge of the metal intervening layer 3 is located inside the outer peripheral edge of the high melting point metal layer 2 as described above, as shown in FIG. Even if the intervening metal layer 3 which has sometimes become a liquid phase flows on the high melting point metal layer 2 in the outer peripheral direction, no pool is formed at the outer peripheral end of the high melting point metal layer 2. Therefore, thermal stress does not concentrate on the outer peripheral end of the high melting point metal layer 2, and the thermal stress applied from the outer peripheral end of the conductive layer 4 to the outer peripheral end of the high melting point metal layer 2 can be further dispersed. Cracking of the ceramic substrate 1 at this portion hardly occurs.

Further, in the present invention, as shown in FIG. 1, the outer peripheral edge of the conductor layer 4 is disposed on the inner peripheral edge of the metal intervening layer 3 or is located inside the outer peripheral edge. It does not protrude from the outer peripheral edge of the intervening layer 3. In addition, similarly, in the combination of the ceramic base 1 and the high melting point metal layer 2, the length and width of the high melting point metal layer 2 can be made smaller than that of the ceramic base 1. Thereby, insulation between the front and back surfaces of the ceramic substrate 1 is maintained, and it is possible to prevent the thermal stress from being concentrated on the outer peripheral end portion of the ceramic substrate 1 and prevent the ceramic substrate 1 from being damaged.

The ceramic substrate used in the present invention preferably has a high thermal conductivity and a high withstand voltage.
In addition to this, those having excellent mechanical strength and toughness are desirable. Further, with the expansion of the use environment of this type of copper circuit bonding substrate, it is becoming important that the copper circuit bonding substrate also has excellent durability against humidity and gas atmosphere. In view of the above, aluminum nitride (Al
N) or silicon nitride (Si ₃ N ₄ ). However, an alumina (Al ₂ O ₃ ) -based material, other ceramics having a single main component, or various ceramics composited with several main components may be selected depending on a load capacity and a use condition.

These ceramic substrates may be added with a sintering aid such as a commonly used rare earth element compound such as Y ₂ O ₃ or an alkaline earth element compound such as CaO. Various additional components such as other transition element compounds such as TiN can be included. Further, the relative density of the ceramic base material is 95% or more, preferably 98% or more. If the relative density is less than 95%, the mechanical strength of the substrate decreases, and the reliability against thermal shock decreases.
Note that a thin layer containing oxygen may be formed in advance on the surface of the ceramic base on which the high melting point metal layer is formed.
l, Si, oxides such as rare earth elements and alkaline earth elements can be included. The higher the thermal conductivity of these ceramic substrates, the better. For example, 100 W / m ·
K or more, preferably 150 W / m · K or more, and Si ₃ N
It is preferably 30 W / m · K or more, preferably 60 W / m · K or more for the ₄ system, and 20 W / mK · or more, preferably 40 W / m · K or more for the Al ₂ O ₃ system.

The role of the refractory metal layer provided on the surface of the ceramic substrate is not limited to the general surface metallization treatment such as circuit formation, but also the coefficient of thermal expansion of the conductor layer mainly composed of copper and the ceramic substrate. The refractory metal layer receives the thermal stress caused by the difference and relieves the thermal stress applied to the ceramic substrate. Further, the surface of the refractory metal layer to be formed is made smooth, and preferably, the surface roughness is made 4 μm or less in average roughness Ra, thereby further stabilizing the stress relaxation effect, reducing the variation in bonding strength, and reducing the thermal cycle. Can be further improved. The thickness of the refractory metal layer after baking is 3
It is desirable to control the thickness to 50 μm. If the thickness is less than 3 μm, it is difficult to obtain sufficient bonding strength with the ceramic substrate,
On the other hand, if the thickness exceeds 50 μm, the amount of warpage after the formation of the metal intervening layer tends to increase.

The main component of the refractory metal layer is a refractory metal, for example, a metal such as W, Ta, Mo, Ti, and Zr. The refractory metal layer includes a glass frit containing a rare earth element, an alkaline earth element, Si, Al and other transition elements added to the sintered body in order to improve the bonding property with the ceramic substrate. May be included. The composition of the refractory metal layer after baking is 80% by volume of the refractory metal.
As described above, the content of the glass frit as described above is preferably 20% by volume or less. When the content of the high melting point metal is less than 80% by volume, the thermal conductivity of the high melting point metal layer tends to decrease, and the same applies when the glass frit exceeds 20% by volume.

The metal intervening layer melts at 1000 ° C. or less,
The refractory metal layer and the conductor layer mainly composed of copper are joined together, and the thermal stress caused by the difference in the coefficient of thermal expansion between the refractory metal layer, the conductor layer and the ceramic substrate is alleviated. Such a metal intervening layer is composed of at least one layer mainly composed of at least one of Ni and Cu, and in particular, a layer having a composition of Ni-P, or at least two or more of Cu, Ni, and P Is preferred. For lamination at the time of manufacturing, for example, Ni-
B-layer and Ni-P layer of a two-layer structure, or Cu-P
It may be performed in a multilayer structure such as a layer, a Cu—Ni—P layer, a Ni—P layer, and a Ni—B layer. At least one layer of two or more of the laminated components Cu, Ni, and P is formed as the metal intervening layer after the bonding. The thickness of the metal intervening layer is 2 to 4
It is preferably 0 μm, more preferably 2 to 10 μm. When the thickness is less than 2 μm, a sufficient bonding strength between the high melting point metal layer and the conductor layer is easily obtained, and when the thickness is more than 40 μm, the overall heat radiation property tends to be reduced due to the metal intervening layer.

The conductor layer mainly composed of copper to be joined to the ceramic substrate through the high melting point metal layer and the metal intervening layer includes, for example, simple copper such as oxygen-free copper and tough pitch copper, copper molybdenum alloy, Examples thereof include copper alloys such as copper-tungsten alloy and copper-molybdenum-tungsten alloy, and cladding materials such as copper-molybdenum-copper having both high electric conductivity and low coefficient of thermal expansion. In addition, if necessary, for example, an Fe—Ni—C such as Kovar
o-based alloys, Fe-Ni-based alloys such as 42 alloy, Ni and its alloys, Cu and its alloys, W, Mo, and their alloys, and are disposed as a semiconductor device around the ceramic substrate. The members may be joined directly or indirectly.

Although the cross-sectional shape of the conductor layer viewed from the side is usually rectangular as shown in FIG. 1, it is desirable that there is no corner or protrusion at the outer peripheral end of the conductor layer in order to avoid a discharge phenomenon.
In order to prevent partial concentration of thermal stress, it is preferable that the cross section be curved or stepped. For example, as shown in FIG. 5, the outer peripheral end section of the conductor layer 4 is formed into a curved shape having an inwardly convex shape, conversely, a curved shape having an outwardly convex shape, or a stepped shape as shown in FIG. be able to.

Further, in the copper circuit bonding substrate of the present invention, an outer layer 5a mainly composed of Ni is provided on the outermost surface of the conductor layer 4 as shown in FIG. An outer layer 5b mainly composed of Ni can be formed on the outer surface and side surfaces. Examples of the outer layer mainly composed of Ni include Ni and Ni-B based alloys. By providing the outer layers 5a and 5b mainly with Ni as described above, the moisture resistance can be improved.

Next, a method of manufacturing a copper circuit bonding board according to the present invention will be described. The manufacturing method of the present invention basically includes a step of forming a high melting point metal layer on a ceramic substrate, and a step of forming a metal intervening layer on a bonding surface side of the conductor layer mainly composed of copper with the high melting point metal layer. And joining the ceramic substrate and the conductor layer mainly composed of copper at a temperature lower than the melting point of the conductor layer via the metal intervening layer. Also,
As a preferred mode of the above manufacturing method, an outer layer mainly composed of Ni is attached to the surface opposite to the joining surface of the conductor layer with the high melting point metal layer, or to the surface opposite to the joining surface and its side surfaces before joining. A forming step can be included.

The ceramic substrate is made of, for example, AlN, Si
₃ N _4, with a main component powder, such as Al ₂ O _3, mixed already various sintering aid powder such as described, etc., by molding a raw material mixture powder obtained, sintering the green body It is obtained by doing. Thereafter, if necessary, a pretreatment for facilitating metallization can be performed on the surface on which the high melting point metal layer is to be formed, for example, by forming an oxide layer.

As a method of forming a high melting point metal layer on a ceramic base material in advance, there are two methods, a postfire metallization method and a cofire metallization method. In the poster metallizing method, a high-melting-point metal paste is printed on a ceramic base made of the sintered body sintered as described above, and the paste is baked by baking in a non-oxidizing atmosphere. On the other hand, in the cofire metallization method, a high-melting-point metal paste is printed and applied on a molded body obtained by molding the above-mentioned ceramic base material mixed powder, and the paste is fired in a non-oxidizing atmosphere to sinter the molded body. At the same time, a refractory metal layer is formed thereon. The cofire metallization method is
The production cost is lower than that of the post-fire metallization method, and a high bonding strength between the high melting point metal layer and the ceramic substrate can be obtained, which is an industrially advantageous method. The high-melting-point metal paste used is prepared by mixing a high-melting-point metal such as W with a glass frit as necessary, and further mixing an organic binder or an organic solvent as described above.

As a material for forming the conductor layer, a plate material is usually used. The outer dimensions of the plate material are shorter than the main surface of the refractory metal layer formed on the ceramic base material in both length and width by 0.05 mm or more, preferably 0.05 to 1 mm.
Process about a short time. Also, the end cross-sectional shape of the conductor layer is preferably processed into a curved shape or a step shape as described above. In addition, these processing methods can be applied by any method as long as it is an existing plate material forming method.

In the method of the present invention, a metal intervening layer is formed in advance on the side of the above-mentioned conductor layer which is to be bonded to the high melting point metal layer. This is because the structure of the present invention can be formed simply and inexpensively. For example, if an attempt is made to form a metal intervening layer on the high melting point metal layer side, it is necessary to perform masking and plating in advance, and then perform etching after plating, which is troublesome. A preferred metal intervening layer is a Ni-P layer, and more preferably a Cu layer is formed on the Ni-P layer. Various methods for forming the metal intervening layer are conceivable, for example, electroplating, electroless plating, thermal spray coating, vapor deposition, printing, and the like. However, in consideration of the productivity at the time of formation, the formation by plating is the most efficient, and the thickness and other qualities can be reliably ensured. In that case, a Ni-B layer may be formed on the conductor layer, and a Ni-P layer and a Cu layer may be formed thereon, particularly in consideration of adhesion.

In the case where an outer layer mainly composed of Ni is formed on the conductor layer, before the conductor layer is joined to the refractory metal layer, the outer surface of the conductor layer opposite to the joining surface with the refractory metal layer is joined. An outer layer mainly composed of Ni is formed on the surface or on the surface and side surface opposite to the joining surface. The outer layer mainly composed of Ni is most efficiently formed by plating, and the quality of the layer such as the thickness can be reliably ensured. Similarly, the plating method may be either electrolytic plating or electroless plating. The thus formed metal intervening layer and outer layer are preferably fired in a non-oxidizing atmosphere.

Next, the ceramic substrate on which the refractory metal layer is formed and the conductor layer on which the metal intervening layer or the metal intervening layer and the outer layer are formed are placed such that the refractory metal layer and the metal intervening layer face each other. By overlapping, heating and joining,
This is a copper circuit bonding board of the present invention. This heat treatment is carried out in a non-oxidizing atmosphere or at a temperature of 10 ^-4 Torr or less in a temperature range that is equal to or higher than the temperature at which the metal intervening layer turns into a liquid phase and lower than the melting point of the conductor layer material, usually 700 to 1000 ° C. Perform in vacuum. When the heat treatment temperature is equal to or higher than the melting point of the conductor layer, the outer peripheral shape of the conductor layer and the formed circuit pattern are easily broken. By this heat treatment, the metal intervening layer temporarily becomes a liquid phase, and forms at least one layer containing two or more of Cu, Ni, and P as described above. For this reason, an alloy having a new composition, for example, an alloy having a composition such as Cu-P or Cu-Ni-P may be generated during cooling.

In order to prevent mutual displacement between the conductor layer and the ceramic substrate during the joining, a jig made of a refractory material such as carbonaceous material, alumina material, or aluminum nitride material may be used as necessary. It can also be used to temporarily fix them to prevent displacement. In addition, in order to prevent displacement and reliably obtain a practically necessary bonding strength level, it is possible to apply an appropriate load to both of the temporarily fixed members as necessary.

In the thus-obtained copper circuit bonding substrate of the present invention, the bonding strength of the bonding portion is at a high level of not less than 0.5 kg / mm which does not cause a practical problem in peeling strength. Is obtained stably. In addition, the measuring method of peeling strength is as follows. That is, as shown in FIG. 9, a conductor layer 4 having a thickness of 0.1 mm and a width of 4.0 mm is interposed between a high melting point metal layer 2 and a metal intervening layer 3 provided on a ceramic substrate 1 to have a length L = 3 mm.
Joining so that In this case, the conductor layer 4 is bent so as to be perpendicular to the bonding portion to form the grip portion 4a. Thereafter, by pulling the grip portion 4a upward, a tensile load at which the bonding layer including the conductor layer 4 or a part of the bonding interface thereof starts to peel is reduced by a length L of 1
The value converted per mm is defined as the peel strength.

[0045]

And AlN powder EXAMPLE 1 The average particle diameter of 1 [mu] m, Y ₂ O ₃ powder having an average particle diameter of 0.6 .mu.m, and a CaO powder having an average particle diameter of 0.3 [mu] m, respectively 97 wt%, 1.5 wt % And 1.5% by weight, and weighed in a ball mill in an ethanol solvent.
After mixing for a time, the sintering aid is made of Y ₂ O ₃ —CaO
An N-based mixed raw material powder was obtained. Further, the mixed raw material powder 1
100 parts by weight of PVB as an organic binder
A slurry was added by adding parts by weight. A part of this slurry was spray-dried, and the obtained powder was molded by a molding press.

Half of these compacts were sintered at 1700 ° C. for 5 hours in a nitrogen atmosphere. The relative density (ratio of the measured density measured by the underwater method when the theoretical density is 100%) of each of the obtained AlN sintered bodies is 99%, and pores and the like are formed on the surface so as to cause a practical problem. There were no defects.
The thermal conductivity of the AlN sintered body measured by the laser flash method was 150 to 160 W / m · K.

A high melting point metal paste was applied to one main surface of these AlN sintered bodies by screen printing, and a high melting point metal layer was formed by a post-fire metallization method. That is, the W powder 80 wt% of the refractory metal was added in small portions to the ball mill, 10 wt% solvent, SiO ₂ -CaO
-B ₂ O ₃ based glass 5 wt%, and an organic binder 5 wt% in admixture with high melting point metal paste. Put this paste in A
After coating on the 1N sintered body and removing the binder in a nitrogen atmosphere, firing was performed at 1650 ° C. for 1 hour in a nitrogen atmosphere to form a high melting point metal layer. The thickness of the obtained refractory metal layer was 20 ± 10 μm.

Using the remaining half of the compacts, a refractory metal layer was formed by a cofire metallization method. That is,
The same high melting point metal paste as described above was printed and applied on one main surface of the molded body, and after removing the binder at 600 ° C. in a nitrogen atmosphere, it was baked at 1700 ° C. for 5 hours in a nitrogen atmosphere to form a molded body. Was sintered and the high melting point metal paste was baked. The thickness of the obtained refractory metal layer is 20 ± 10 μm.
Met. The size of the metallized substrate on which the W refractory metal layer was formed in the above steps was 50 mm in width and 50 m in length.
m and thickness 0.8 mm.

Next, both the length and width are 0.1 mm shorter than the refractory metal layer (ΔL = 0.1 mm) and the thickness is 0.3 m.
m from the high melting point metal layer in both length and width.
Prepare 30 copper plates each of which is 30 mm short (△ L = 0.5 mm) and 0.3 mm in thickness, Ni-P plated on one side thereof, and held at 600 ° C. for 30 minutes in a nitrogen atmosphere. It was fired to form a metal intervening layer. No abnormalities such as blisters and peeling were found in the obtained metal intervening layer. In all samples, the plating thickness of the metal intervening layer was in the range of 6 ± 1 μm. In addition, a copper material of JIS C1020 was used as a material of the copper plate, and three end types of the rectangular shape in FIG. 1, the curved shape in FIG. 5, and the step shape in FIG.

Further, the metallized substrate on which the refractory metal layer was formed as described above and the copper plate on which the Ni-P metal interposed layer was formed were combined with the Ni-P plated surface of the copper plate (metal interposed layer).
Are arranged on a graphite setter so as to be in close contact with the refractory metal layer, and 1000 ° C. × 30 in a nitrogen stream.
Bonding was performed in a furnace without any load for 5 minutes to produce a copper circuit bonded substrate.

Each of the obtained substrates was observed with an optical microscope of 100 times, and it was confirmed that the outer peripheral edge of the metal interposed layer did not protrude from the outer peripheral edge of the high melting point metal layer. In addition, no abnormal defect was observed in each of the samples after bonding by ultrasonic flaw detection surface analysis. Furthermore, the cross section after bonding is 1000 times S
When observed with an EM (scanning electron microscope), no cracks, pinholes, etc. were found at the interfaces of all the samples. The peel strength of the conductor layer was 1.5 to 2.5 kg in all cases.
/ Mm range.

A heat cycle test of 1000 cycles was performed on each of the copper circuit boards thus manufactured under the conditions of −55 ° C. × 10 minutes → + 160 ° C. × 10 minutes.
The presence or absence of defects such as peeling or cracks at the joint end surface was examined with a stereo microscope of 0 magnification, and the number of defects due to the presence of defects was determined and is shown in Table 1 below.

COMPARATIVE EXAMPLE 1 A refractory metal layer was formed on an AlN ceramic base material by a post-fire metallization method and a cofire metallization method in the same manner as in Example 1, and Ni was deposited on the refractory metal layer of the metallized substrate. -P plating was performed, and held at 600 ° C. for 30 minutes in a nitrogen atmosphere to form a Ni-P metal intervening layer. No abnormalities such as blisters and peeling were observed in the obtained metal intervening layer. In each of the samples, the plating thickness of the metal intervening layer was in the range of 6 ± 1 μm. On the metal intervening layer of each of these samples, the same copper plate as used in Example 1 (but not subjected to Ni-P plating) was placed, and the bonding was performed in the same manner as in Example 1 to produce a copper circuit bonded substrate. did.

When each sample of the comparative example after bonding was subjected to ultrasonic flaw detection surface analysis, no abnormal defect was found. In addition, the cross section of each sample after bonding was made 1000 times SE.
Observation with a scanning electron microscope (M) revealed no cracks, pinholes, etc. at the interface. Further, the peel strength of the conductor layer of each sample was 1.3 to 2.5 kg / m.
m. The same heat cycle test as in Example 1 was performed on the copper circuit bonding substrates of the respective samples of the comparative example manufactured in this manner, and the number of defects based on the presence or absence of defects was determined.

For each of the samples of Example 1 and Comparative Example 1, the results regarding the number of defects after the heat cycle test were determined based on the manufacturing method of the refractory metal layer and the dimensional difference between the conductor layer and the refractory metal layer.
Table 1 below shows L and the cross-sectional shape of the conductor layer.

[0056]

[Table 1] (Note) In the manufacturing method, PF indicates the post-fire metallization method, and CF indicates the co-fire metallization method.

Example 2 Instead of performing only Ni-P plating on one side of a copper plate serving as a conductor layer, using each metallized substrate prepared in Example 1 above, Ni-P plating having a thickness of 6 ± 1 μm and A copper circuit bonding substrate was prepared in the same manner as in Example 1 except that a Cu plating of thickness 2 ± 1 μm was performed, and bonding was performed in a furnace at 950 ° C. for 30 minutes under no load in a nitrogen stream. Produced.

After the joining, it was confirmed by observation with an optical microscope of 100 times that the outer peripheral edge of the metal interposed layer did not protrude from the outer peripheral edge of the refractory metal layer in all samples. In addition, as a result of ultrasonic inspection surface analysis after joining, no abnormal defect was found in any of the samples. Further, when the cross section after bonding was observed with a SEM (scanning electron microscope) at a magnification of 1000 times, no crack, pinhole, or the like was found at the bonding interface. Further, it was confirmed that the metal intervening layer after bonding was an alloy layer formed by diffusion of Ni, P, and Cu.
(Energy Dispersion X-ray Analyzer).
The peel strength of the conductor layer was 1.8 to 3.0 kg / mm.
Was in the range.

With respect to the copper circuit bonding substrate of each sample prepared in this manner, the temperature was -55 ° C. × 10 minutes → + 160 ° C. × 10
A heat cycle test of 1000 cycles was performed under the conditions of minutes, and the presence or absence of defects such as peeling or cracks at the joint end face was examined with a 20 × stereo microscope. The number of defects due to defects was determined and is shown in Table 2 below.

Comparative Example 2 Using each of the metallized substrates prepared in Example 1 above, Cu plating of 2 ± 1 μm thickness was applied on the refractory metal layer and Ni—P plating of 6 ± 1 μm thickness was applied thereon. The same copper plate (but not plated) used in Example 1 was placed on the metallized substrate of No. 1 and joined in the same manner as in Example 2.

As a result of the ultrasonic flaw detection surface analysis, no abnormal defect was observed in each sample of the comparative example after bonding. In addition, the cross section after bonding is SEM (scanning electron microscope) of 1000 times.
As a result, no crack, pinhole or the like was found at the joint interface. The peel strength of the conductor layer was 1.
It was in the range of 4-2.3 kg / mm.

For each sample of Comparative Example 2 above,
The number of defects after the heat cycle test, which was evaluated in the same manner as described above, is shown in Table 2 below together with the manufacturing method of each refractory metal layer, the dimensional difference ΔL between the conductor layer and the refractory metal layer, and the cross-sectional shape of the conductor layer. .

[0063]

[Table 2] (Note) In the manufacturing method, PF indicates the post-fire metallization method, and CF indicates the co-fire metallization method.

Example 3 Instead of performing only Ni-P plating on one surface of a copper plate using each of the metallized substrates prepared in Example 1 above,
± 1μm Ni-P plating and 2 ± 1μm thick
Cu plating is performed, and the other surface (conductor layer main surface) of the copper plate is Ni-B plated with a thickness of 2 ± 1 μm as an outer layer,
5 in the same manner as in Example 1 except that the in-furnace bonding was performed at 950 ° C. for 30 minutes under no load in a nitrogen stream.
As shown in FIG. 7, a copper circuit bonding board having a curved end cross section at the end of the conductor layer and having an outer layer of Ni-B on the conductor layer as shown in FIG. 7 was produced.

After the joining, it was confirmed by an optical microscope observation at a magnification of 100 times that the outer peripheral edge of the metal interposed layer did not protrude from the outer peripheral edge of the refractory metal layer in all samples. In addition, as a result of performing an ultrasonic inspection surface analysis on each of the samples after bonding, no abnormal defect was recognized. Further, when the cross section after bonding was observed with a SEM (scanning electron microscope) at a magnification of 1000 times, no crack, pinhole, or the like was found at the bonding interface.

The 10 samples thus prepared and the 10 samples in which the conductor layer prepared in Example 2 had the curved end cross-sectional shape shown in FIG.
The moisture resistance test for 2 hours was repeated five times under the condition of%, and a visual test of the outer periphery of each sample was performed for each moisture resistance test to check particularly the discoloration and deterioration of the main surface of the conductor layer. In this case, before and after the test, a change in the state of the phase on the surface was confirmed by X-ray diffraction of the main surface of the conductor layer.

As a result, by forming the outer layer of Ni-B on the main surface of the conductor layer, the moisture resistance was remarkably improved, and all the samples having the outer layer formed on the main surface of the conductor layer after the moisture resistance test were performed five times. No discoloration and deterioration, and no change in the phase of the main surface were observed. However, in the sample in which the outer layer was not formed on the main surface of the conductor layer, a thin layer of cuprous oxide was formed on the surface of the conductor layer after the first moisture resistance test, and deterioration was observed.

Example 4 Instead of performing only Ni-P plating on one surface of a copper plate, using each metallized substrate prepared in Example 1 above,
± 1μm Ni-P plating and 2 ± 1μm thick
Except that the other side of the copper plate was subjected to Ni-B plating with a thickness of 2 ± 1 μm as an outer layer, and the furnace was joined in a nitrogen stream at 950 ° C. for 30 minutes with no load. A copper circuit bonding substrate was produced in the same manner as in Example 1. In Example 4, all the layers and the copper plate were formed on both surfaces of the ceramic base material.

After the joining, it was confirmed by an optical microscope observation at a magnification of 100 that the outer peripheral edge of the metal interposed layer did not protrude from the outer peripheral edge of the refractory metal layer in all the samples. Also,
As a result of ultrasonic inspection surface analysis for each sample after joining,
No abnormal defects were found. Furthermore, when the cross section after bonding was observed with a SEM (scanning electron microscope) at a magnification of 1000, no crack, pinhole, or the like was found at the bonding interface of each sample.

As shown in FIG. 10, each of the obtained substrates
Refractory metal layer 2, metal intervening layer 3, conductor layer 4, and outer layer 5 on both sides of ceramic substrate 1 of 1N sintered body in order from the substrate side.
The main surface and the side opposite to the main surface were joined to a heat radiating plate 6 made of a Cu-W alloy using eutectic solder 7. Further, the semiconductor element 8 is die-bonded to the outer layer 5 on the main surface of the conductor layer 4 and connected with the lead 9, and is housed in a casing 15 having external terminals 16 as shown in FIG.
7 was filled to obtain a semiconductor device.

With respect to the semiconductor device manufactured in this manner, one time was applied under the condition of -55 ° C. × 10 minutes → + 160 ° C. × 10 minutes.
A heat cycle test of 000 cycles was carried out, and the presence or absence of defects that could be a practical obstacle such as cracks or peeling of the joints or surface alteration was examined with a 20 × stereo microscope. It was shown to.

Comparative Example 4 A 2 ± 1 μm thick Cu plating was formed on the refractory metal layer of the metallized substrate prepared in Example 1 and a 6 mm thick
Ni-P plating of ± 1 μm is performed, and the same copper plate (but not plated) used in Example 1 is mounted thereon, and bonding is performed in the same manner as in Example 4 to produce a copper circuit bonding substrate. did.

As a result of the ultrasonic inspection surface analysis of each of the samples after bonding, no abnormal defect was recognized. When the cross section after bonding was observed with a SEM (scanning electron microscope) at a magnification of 1000, no crack, pinhole, or the like was found at the bonding interface. After the Ni-B plating having a thickness of 2 ± 1 μm was applied as an outer layer to the copper circuit bonding substrate thus manufactured, a semiconductor device was manufactured in the same manner as in Example 4. The obtained semiconductor device was subjected to the same heat cycle test and evaluation as in Example 4 above, and the results are shown in Table 3.

[0074]

[Table 3] (Note) In the manufacturing method, PF indicates the post-fire metallization method, and CF indicates the co-fire metallization method.

[0075]

According to the present invention, when a conductor layer made of a metal member such as a lead frame is mounted on a ceramic base material such as aluminum nitride, it is generated by conventional brazing or eutectic bonding. It is possible to easily and inexpensively provide a copper circuit bonding substrate for a semiconductor device which eliminates breakage and deformation of a base material, suppresses warpage, has high bonding strength, and greatly improves reliability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a specific example of a copper circuit bonding board of the present invention.

FIG. 2 is a schematic sectional view showing a conventional copper circuit bonding substrate.

FIG. 3 is a schematic cross-sectional view schematically showing an outer peripheral end of a metal interposed layer in the copper circuit bonding board of the present invention.

FIG. 4 is a schematic cross-sectional view schematically showing an outer peripheral end of a metal intervening layer in a conventional copper circuit bonding substrate.

FIG. 5 is a schematic cross-sectional view showing a copper circuit bonding substrate in which a cross-sectional shape of an end of a conductor layer of the present invention is a curved surface.

FIG. 6 is a schematic cross-sectional view illustrating a copper circuit bonding substrate having a stepped end cross-sectional shape of a conductor layer according to the present invention.

FIG. 7 is a schematic cross-sectional view showing a copper circuit bonding substrate having an outer layer according to the present invention.

FIG. 8 is a schematic cross-sectional view showing another copper circuit bonding substrate having an outer layer according to the present invention.

FIG. 9 is a cross-sectional view for explaining a method of measuring the peel strength of the copper circuit bonding board according to the present invention.

FIG. 10 is a schematic cross-sectional view showing a member in which a copper circuit bonding substrate manufactured in Example 4 is bonded to a heat sink.

FIG. 11 is a schematic partially cutaway side view showing a semiconductor device manufactured in Example 4.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 11 Ceramic base material 2, 12 Refractory metal layer 3, 13 Metal intervening layer 4, 14 Conductive layer
5, 5a, 5b Outer layer 6 Heat sink 7 Eutectic solder 8 Semiconductor element 9 Lead 15 Casing 16 External terminal 17 Resin

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazutaka Sasaki 1-1-1, Koyokita-Kita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Takashi Ishii, Kochi-Kita1, Itami-shi, Hyogo No. 1-1 In Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Hirohiko Nakata 1-1-1, Koyo-Kita-Kita, Itami-shi, Hyogo F-term in Sumitomo Electric Industries, Ltd. Itami Works F-term (reference) 4E351 AA09 AA12 BB01 BB30 BB31 BB35 BB38 CC06 CC07 CC08 CC09 CC12 CC23 CC31 CC33 DD04 DD17 DD19 DD28 DD47 DD52 EE10 EE11 GG01 GG02 GG04 5E343 AA02 AA23 BB13 BB17 BB24 BB39 BB40 BB44 BB57 BB67 BB72 BB73 BB75 ER23 DD33 DD33 DD33 DD33

Claims (10)

[Claims] 1. A ceramic substrate, a refractory metal layer mainly composed of a refractory metal provided on one or both sides of the ceramic substrate in order from the substrate side, and at least one of nickel and copper. At least one metal intervening layer as a main component;
A copper circuit bonding substrate comprising a copper-based conductor layer, wherein the length and width of the metal interposition layer at the bonding interface between the refractory metal layer and the metal interposition layer in the planar direction are different from those of the refractory metal layer. 0.05 mm or more shorter than them, whether the outer peripheral edge of the metal intervening layer is inside the outer peripheral edge of the refractory metal layer, and whether the outer peripheral edge of the conductor layer is on the outer peripheral edge of the metal intervening layer. Or a copper circuit bonding board characterized by being inside. 2. The copper circuit bonding board according to claim 1, wherein the metal intervening layer is formed of an alloy layer containing at least two of copper, nickel, and phosphorus. 3. The copper circuit bonding board according to claim 1, wherein an outer layer mainly composed of Ni is formed on the outermost surface of the conductor layer or on the outermost surface and side surfaces. . 4. The ceramic substrate according to claim 1, wherein said ceramic substrate is made of an aluminum nitride-based ceramic.
A copper circuit bonding board according to any one of the above. 5. The copper circuit bonding board according to claim 1, wherein said high melting point metal layer is tungsten. 6. A semiconductor device formed by die bonding a semiconductor element to the copper circuit bonding substrate according to claim 1. 7. A method for manufacturing a copper circuit bonding substrate comprising a ceramic base and a conductor layer mainly composed of copper, comprising applying a paste containing a high melting point metal to a ceramic base made of a sintered body. Baking a high-melting-point metal layer, and providing a conductor layer mainly composed of copper with a length and width in the plane direction smaller than those of the high-melting-point metal layer on the joining surface side with the high-melting-point metal layer. .05mm or more, at least one of nickel and copper
A step of forming a metal interposed layer containing a seed as a main component; and a step of forming a ceramic base provided with the high melting point metal layer and the conductor layer through the metal interposed layer, the outer peripheral edge of the metal interposed layer having a high melting point metal. Bonding at a temperature lower than the melting point of the conductor layer so as to be inside the outer peripheral edge of the layer. 8. A method for manufacturing a copper circuit bonding board having a conductor layer mainly composed of copper on a ceramic substrate, comprising applying a paste containing a high melting point metal on a molded body of ceramic raw material powder and firing the paste. Forming a high-melting metal layer on the ceramic substrate at the same time as obtaining the ceramic substrate, and the bonding surface side of the copper-based conductor layer with the high-melting metal layer, the length in the planar direction and The width is more than that of those of the refractory metal layer.
A step of forming a metal intervening layer which is at least 05 mm shorter and contains at least one of nickel and copper as a main component; Bonding at a temperature lower than the melting point of the conductor layer so that the outer peripheral edge of the intervening layer is inside the outer peripheral edge of the high melting point metal layer. 9. The method according to claim 7, wherein a nickel-phosphorus layer is formed on the conductor layer, or a copper layer is further formed on the nickel-phosphorus layer as the metal intervening layer. 9. The method for producing a copper circuit bonding substrate according to item 8. 10. Before joining the conductor layer and the ceramic substrate, the conductor layer has a surface opposite to the joint surface with the refractory metal layer, or a surface opposite to the joint surface and a side surface thereof. Forming an outer layer mainly composed of:
10. The method for manufacturing a copper circuit bonding board according to any one of the above items 9.