JP6429108B2 - Semiconductor element mounting substrate and semiconductor element device using the same - Google Patents

Description

  The present invention relates to a semiconductor element mounting substrate made of a diamond composite material in which a large number of minute diamond particles are bonded by a bonding material, and a semiconductor element device using the semiconductor element mounting substrate.

In order to prevent a semiconductor element such as a semiconductor laser from malfunctioning due to its own heat generation, a semiconductor element mounting substrate (heat sink, heat dissipation board, housing, etc.) connected to the semiconductor element has a heat dissipation property. It needs to be excellent.
For this reason, conventionally, it has been common to form a semiconductor element mounting substrate from a ceramic having high thermal conductivity and good heat dissipation, such as AlN or SiC. However, with the recent increase in output of semiconductor elements, semiconductor element mounting substrates are required to have higher heat dissipation than the current situation.

Therefore, in order to meet this requirement, a semiconductor element mounting substrate is formed of a diamond composite material in which a large number of minute diamond particles are bonded together by a bonding material made of a metal such as Cu or Ag or a ceramic such as SiC. Proposed to do.
Since diamond has the highest thermal conductivity in a substance with a theoretical thermal conductivity of 2000 W / m · K, if a semiconductor element mounting substrate is formed using the diamond composite material containing such diamond, It is considered that the thermal conductivity can be dramatically improved as compared with a conventional ceramic or the like.

In order to conduct heat conduction as smoothly as possible between a semiconductor element mounting substrate made of a diamond composite material and a semiconductor element connected (mounted) to the semiconductor element mounting substrate, the semiconductor element mounting substrate, the semiconductor element, However, it is necessary to be connected in close contact with each other through a layer of solder or brazing material as much as possible.
The same applies to other heat radiating members that are thermally connected to the semiconductor element mounting substrate and assist the heat radiation from the semiconductor elements. In order to conduct heat conduction as smoothly as possible between the semiconductor element mounting substrate and the other heat radiating member, the semiconductor element mounting substrate and the other heat radiating member have as little gap as possible through the solder or brazing material layer. It is necessary to be connected in close contact.

For this purpose, the element mounting surface for connecting the semiconductor elements of the semiconductor element mounting substrate made of a diamond composite material and other heat dissipation members (hereinafter including the semiconductor elements are collectively referred to as “other members”). It is necessary that the connection surface with other members such as a heat transfer surface for thermally connecting is finished as smoothly as possible.
Therefore, in order to finish the connecting surface of the semiconductor element mounting substrate smoothly, conventionally, such a connecting surface is generally polished using a diamond grindstone or the like. Also, the polished connection surface may be covered with a metal film.

For example, in Patent Document 1, a subcarrier for mounting a semiconductor laser as a substrate for mounting a semiconductor element is formed of a diamond composite material, and its connection surface is defined by Japanese Industrial Standards JIS B0601: 2001 “Geometric Characteristics Specification of Products (GPS)”. - surface texture: profile curve method - terms, definitions and defined in the surface texture parameters ", the arithmetic mean roughness R _a of a roughness curve showing a surface roughness is polished so as to 0.5μm or less, The polished connection surface has a first metal film made of at least one metal selected from the group consisting of Ni, Cr, Ti, and Ta, Mo, Pt, Au, Ag, Sn, Pd, Ge, and The coating is described in this order with a second metal film made of at least one metal selected from the group consisting of In.

Further, Patent Documents 2 and 3, to form a heat sink as a substrate for mounting a semiconductor element by diamond composite material, respectively, the connection surface, the arithmetic mean roughness R _a is, Patent Document 2 0.2μm or less, patent Document 3 describes that polishing is performed to 0.5 μm or less, and that the polished connection surface is covered with the first and second metal films similar to those described above.

However, a substrate for mounting a semiconductor element made of a general diamond composite material in which the volume ratio of diamond particles to the total amount of the diamond particles and the binder is 60% by volume or more has low workability. For example, a diamond grindstone is used. Since the polishing process takes a long time, there is a problem that the productivity of the substrate for mounting a semiconductor element is lowered and the manufacturing cost is increased.
For example, when the connection surface of the semiconductor element mounting substrate made of such a diamond composite material is polished to a predetermined surface roughness by planar polishing using a diamond grindstone of # 100 to # 400, It takes about 20 hours or more to finish the connection surface.

Moreover, even if the connection surface can be polished to a predetermined surface roughness, the connection surface is caused by the recesses generated by the falling of diamond particles during polishing or the diamond particles remaining without being polished. There are many convex parts to be
Therefore, the unevenness generated on the connection surface by the concave portion or the convex portion prevents the close contact between the connection surface and the other member via the solder or brazing material layer, and easily causes a gap between the two. The gap causes a reduction in the efficiency of heat conduction between the semiconductor element mounting substrate and the other member.

Even if the connection surface and the other member can be brought into close contact with each other without any gaps, the recesses present on the connection surface remain as gaps that hinder heat conduction at the interface between them, so that the semiconductor element mounting This causes a reduction in the efficiency of heat conduction between the substrate for use and other members.
Therefore, in any of these cases, there is also a problem that the thermal conductivity of the substrate for mounting a semiconductor element cannot be sufficiently improved by fully utilizing the good thermal conductivity of the diamond composite material.

Therefore, the conventional semiconductor element mounting substrates described in Patent Documents 1 to 3 cannot sufficiently cope with the further increase in output of semiconductor elements such as semiconductor lasers in recent years, and the semiconductor elements operate by their own heat generation. At present, the effect of preventing the occurrence of defects is becoming insufficient.
Further, the size of the recesses and protrusions depends on the particle size of the diamond particles, and the depth or height is as large as about 5 to 300 μm, whereas the metal formed on the connection surface in Patent Documents 1 to 3 The thickness of the film is significantly smaller than that.

For example, in Example 3 of Patent Document 1, the maximum value of the thickness of the Ni film as the first metal film is set to 2 μm, and the thickness of the Au film as the second metal film is set to 0.2 μm. The maximum thickness is only 2.2 μm.
In Example 3 of Patent Document 3, the thickness of the Ni film as the first metal film is set to 1 μm, the thickness of the Pt film as the second metal film is set to 0.2 μm, and the total thickness is 1 Only 2 μm.

Therefore, even if the connection surface is covered with a two-layer metal film, it fills the recesses and protrusions, that is, fills the metal with the metal forming the metal film so that the recesses do not remain as voids. It is difficult to smooth the connecting surface by burying the part in the metal film.
In Patent Document 4, a radiator as a semiconductor element mounting substrate is formed of a diamond composite material, and a Cu material layer having a thickness larger than that of the metal film described above is formed on the connection surface of the radiator. It is described that the surface of the Cu material layer is made a smooth surface by filling the concave portions and the convex portions.

  According to such a configuration, the unevenness of the connection surface described above prevents the close contact with the other member and creates a gap between them, or the recess remains as a gap that prevents heat conduction at the interface between the two. Therefore, the connection surface and the other member can be connected to each other with the Cu material layer and the solder or brazing material layer in close contact with each other without any gap.

JP 2003-309316 A JP 2004-175626 A JP 2005-184021 A JP 2005-175006 A

  However, the thermal conductivity of Cu is lower than that of the diamond composite material. Therefore, as described in Patent Document 4, a layer of Cu material having a large thickness that can fill in the recesses and protrusions present on the connection surface of the semiconductor element mounting substrate, even if the surface is smooth, Even if the other member can be brought into close contact via the solder or brazing material layer, the effect of improving the efficiency of heat conduction is insufficient.

In addition, the Cu material layer has a large difference in thermal expansion coefficient from the diamond composite material, and has a higher internal stress due to the larger thickness. Therefore, the Cu material is formed on the Cu material layer by, for example, a heat history when connecting other members via a solder or brazing material layer, or a heat history due to heat generated by the element itself when driving the semiconductor element. There is also a problem that the layer itself is easily peeled off from the connection surface.
The object of the present invention is excellent in workability, and can form a connection surface with as few irregularities as much as possible in a short time, thereby improving the efficiency of heat conduction with other members such as semiconductor elements. It is an object of the present invention to provide a semiconductor element mounting substrate that can improve and prevent the semiconductor element from malfunctioning due to its own heat generation by fully utilizing the high thermal conductivity of the diamond composite material.

  Another object of the present invention is to prevent the semiconductor element connected to the connection surface of the semiconductor element mounting substrate of the present invention from causing a malfunction due to its own heat generation. An object of the present invention is to provide a semiconductor element device that can be driven for a long period of time.

The present invention comprises a diamond composite material in which a large number of diamond particles are bound together by a binding material,
Having a connection surface with other members,
The binder is a combination of any one of the following (I) to (IV) , and the thermal expansion coefficient of the diamond composite material from 25 ° C. to 400 ° C. is 5.0 × 10 ⁻⁶ / K or more. 8.5 × 10 ⁻⁶ K or less,
It is a board | substrate for semiconductor element mounting.
(I) The binder is
(A) Cu as the first metal, and
(B) Mo as the second metal
The volume ratio of the diamond particles occupying the total amount of the diamond particles and the two metals is y, and the volume ratio of Mo occupying the total amount of the two metals is x = B / ( A + B) × 100 [volume%, A is Cu volume%, B is Mo volume%], the volume ratio y is 40 volume% or more and 55 volume% or less, and the x and y are formulas (1) (2):
y ≧ −5.37x + 100 (1)
y ≦ −0.72x + 91 (2)
Satisfied.
(II) The binder is
(A) Cu as the first metal, and
(B) W as the second metal
The volume ratio of the diamond particles in the total amount of the diamond particles and the two types of metals is y, and the volume ratio of the W in the total amount of the two types of metals is x = B / ( A + B) × 100 [volume%, A is the volume% of Cu, and B is the volume% of W], the volume ratio y is 40 volume% or more and 55 volume% or less, and the above x and y are formulas (3) (4):
y ≧ −5.37x + 100 (3)
y ≦ −0.92x + 101 (4)
Satisfied.

(III) The binder is
(A) Ag as the first metal, and
(B) Mo as the second metal
The volume ratio of the diamond particles occupying the total amount of the diamond particles and the two metals is y, and the volume ratio of Mo occupying the total amount of the two metals is x = B / ( A + B) × 100 [volume%, A is volume% of Ag, B is volume% of Mo], the volume ratio y is 40 volume% or more and 55 volume% or less, and the above x and y are formulas (5) (6):
y ≧ −0.74x + 49 (5)
y ≦ −1.33x + 127 (6)
Satisfied.
(IV) The binder is
(A) Ag as the first metal, and
(B) W as the second metal
Of the two types,
The volume ratio of the diamond particles in the total amount of the diamond particles and the two metals is y, and the volume ratio of W in the total amount of the two metals is x = B / (A + B) × 100 [volume. %, A is volume% of Ag, and B is volume% of W], the volume ratio y is 40 volume% or more and 55 volume% or less, and
Said x and y are formulas (7) (8):
y ≧ −0.74x + 49 (7)
y ≦ −0.83x + 102 (8)
Satisfied.
Moreover, this invention is a semiconductor element apparatus with which the semiconductor element was connected to the connection surface of this semiconductor element mounting board | substrate of this invention.

  According to the present invention, it is excellent in workability and can form a connection surface with as little unevenness as possible in a short period of time, thereby improving the efficiency of heat conduction with other members such as semiconductor elements. It is possible to provide a semiconductor element mounting substrate that can be improved and that the high thermal conductivity of the diamond composite material can be fully utilized to prevent the semiconductor element from causing malfunction due to its own heat generation.

  Further, according to the present invention, it is possible to prevent the semiconductor element connected to the connection surface of the semiconductor element mounting substrate of the present invention from causing a malfunction due to its own heat generation. A semiconductor element device that can be continuously driven for a long period of time can be provided.

It is a graph which shows the relationship between the volume ratio of a diamond, and the volume ratio of Cu and Mo in the Example which used together Cu as a 1st metal among this invention, and Mo as a 2nd metal, and a comparative example. . It is a graph which shows the relationship between the volume ratio of a diamond, and the volume ratio of Cu and W in the Example and comparative example which used together Cu as a 1st metal among this invention, and W as a 2nd metal. It is a graph which shows the relationship between the volume ratio of a diamond, and the volume ratio of Ag and Mo in the Example which used together Ag as a 1st metal among this invention, and Mo as a 2nd metal, and a comparative example. . It is a graph which shows the relationship between the volume ratio of a diamond, and the volume ratio of Ag and W in the Example which used together Ag as a 1st metal among this invention, and W as a 2nd metal, and a comparative example.

<Semiconductor element mounting board>
The present invention comprises a diamond composite material in which a large number of diamond particles are bound together by a binding material,
Having a connection surface with other members,
The binder is (A) Cu and (B) Mo, (A) Cu and (B) W, (A) Ag and (B) Mo, or (A) Ag and (B) W ,
The volume ratio of the diamond particles in the total amount of the diamond particles and the two types of metals is y, and the volume ratio of the W in the total amounts of the two types of metals is x = B / (A + B) × 100. The volume ratio y is 40 volume% or more and 55 volume% or less, and the x and y are the above-described formulas (1), (2), and (3) depending on the two kinds of metals to be combined. ) And formula (4), formula (5) and formula (6), or formula (7) and formula (8),
The thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ K or less.
It is a board | substrate for semiconductor element mounting.

Bonding materials such as Cu, Ag, Al, and Mg, which constitute a semiconductor element mounting substrate made of a diamond composite material, have a relatively high thermal conductivity among metal materials, and thus assist high heat conduction by diamond particles. It is known that it has excellent machinability and good machinability.
Therefore, when the volume ratio of the binder in the total amount of the diamond particles and the binder is relatively increased so that the volume ratio of the diamond particles is smaller than a general range of 60% by volume or more, the diamond composite material The workability can be improved while maintaining good thermal conductivity of the semiconductor element mounting substrate.

In other words, the connecting surface can reduce the unevenness due to diamond grain detachment and polishing residue generated during polishing processing, and has excellent smoothness without forming the various conventional coating layers described above, and can adhere other members without gaps. Can be formed by polishing as short as possible.
However, when the volume ratio of the binder increases, the thermal expansion coefficient of the diamond composite material increases, and in particular, the difference in the thermal expansion coefficient from the semiconductor element increases.

As a result, other members such as the semiconductor element are easily damaged or disconnected from the connection surface due to expansion or contraction due to thermal history when connecting other members to the connection surface or operating the semiconductor element. A new problem arises.
Therefore, the inventor further examined the binder. As a result, in addition to Cu or Ag (hereinafter may be collectively referred to as “first metal”) among ordinary binders, the first metal does not or hardly dissolve in the first metal. have small coefficient of thermal expansion than the first metal M o or W (hereinafter may be collectively referred to as "second metal"), it was found that it is sufficient in combination as a binder.

That is, since the second metal has a small coefficient of thermal expansion, the coefficient of thermal expansion of the diamond composite material is adjusted by using the second metal in combination with the first metal, and in particular, the coefficient of thermal expansion with the semiconductor element. Can be made as small as possible.
In addition, since the second metal does not dissolve at all or hardly dissolves with the first metal, the second metal does not cause a lattice displacement or a decrease in electronic conduction associated therewith. Good heat conduction by one metal can be maintained.

Therefore, by combining the first and second metals as a binder, the workability is improved while maintaining good thermal conductivity of the substrate for mounting semiconductor elements by increasing the volume ratio of the binder. It is possible to suppress the increase in the coefficient of thermal expansion of the diamond composite material while keeping the effect of the above in good condition, and in particular to approach the coefficient of thermal expansion of the semiconductor element.
For this reason, it is possible to prevent other members such as a semiconductor element from being damaged or disconnected from the connection surface due to expansion and contraction when a thermal history is applied.

Such a substrate for mounting a semiconductor element of the present invention can be manufactured in the same manner as in the prior art, except that the first and second kinds of metals are used in combination as the binder. In particular, it can be suitably manufactured by the manufacturing method using the ultrahigh pressure generator described in Patent Documents 1 to 3 described above.
That is, the diamond particles and the first and second metals as the binder are mixed in a predetermined volume ratio and sealed in a capsule made of molybdenum or the like, in a vacuum, in an inert gas atmosphere, or After heating and sintering in a reducing atmosphere, pressurize and sinter, then remove the capsule, then process into a predetermined shape, cut the connecting surface by electric discharge machining, polishing with a diamond grindstone, or blasting, etc. The substrate for mounting a semiconductor element of the present invention is manufactured by finishing by one or more kinds of processing.

The pressure applied during sintering is preferably 1 GPa or more, particularly preferably 4 GPa or more, and preferably 6 GPa or less. The heating temperature is preferably 1100 ° C. or higher, preferably 1500 ° C. or lower, particularly preferably 1200 ° C. or lower.
At the time of sintering, the capsule is heated to a predetermined temperature under the predetermined pressure to melt at least the first metal of the two kinds of metals as the binder and to penetrate between the diamond particles. It is preferable to recover the capsule by lowering the temperature to 900 ° C. or lower (including normal temperature) and holding it for a certain period of time by solidifying the first metal and then returning to normal pressure and normal temperature.

<Diamond particles>
As the diamond particles, any natural or synthetic diamond particles having a theoretical thermal conductivity of 2000 W / m · K and the highest thermal conductivity among substances can be used.
The average particle diameter of the diamond particles is preferably 5 μm or more, particularly preferably 10 μm or more, and is preferably 100 μm or less, particularly preferably 50 μm or less.

If the average particle size of the diamond particles is less than this range, the interface area between the diamond particles and the two kinds of metals as the binder increases, so that the thermal resistance of the diamond composite material increases, and the heat of the substrate for mounting the semiconductor element Conductivity may be reduced.
On the other hand, when the average particle diameter of the diamond particles exceeds the above range, workability such as polishing is reduced, and the size of the concave and convex portions generated on the connection surface is increased, and the smoothness of the connection surface is reduced. Then, there is a possibility that other members such as a semiconductor element cannot be adhered without a gap.

In addition, as described in Patent Document 3, for example, a coating layer made of the same material as the binder may be formed on the surface of the diamond particles.
<Binder>
As the binder, as described above, the first metal that is Cu or Ag and the second metal that is Mo or W are used in combination.

These two metals are preferably in the form of particles in order to be uniformly mixed with the diamond particles.
Among these, the first metal particles preferably have an average particle size of 0.1 μm or more, particularly 1 μm or more, preferably 100 μm or less, particularly 50 μm or less.
Since the fine first metal particles having an average particle diameter less than this range are not easy to manufacture and handle, the productivity of the substrate for mounting a semiconductor element may be lowered and the manufacturing cost may be high.

On the other hand, when the average particle diameter of the first metal particles exceeds the above range, segregation of the first metal may easily occur in the diamond composite material.
For the same reason, the second metal particles preferably have an average particle size of 0.1 μm or more, particularly 1 μm or more, and preferably 100 μm or less, particularly 50 μm or less.
That is, since the fine second metal particles having an average particle diameter less than this range are not easy to manufacture and handle, the productivity of the substrate for mounting a semiconductor element may be reduced, and the manufacturing cost may be high.

On the other hand, when the average particle size of the second metal particles exceeds the above range, segregation of the second metal is likely to occur in the diamond composite material.
<Volume ratio>
In the present invention, the volume ratio y of the diamond particles in the total amount of the diamond particles and the two kinds of metals is limited to 40% by volume or more and 55% by volume or less for the following reason.

That is, when the volume ratio y of the diamond particles is less than this range, the effect of greatly improving the thermal conductivity of the semiconductor element mounting substrate due to the diamond particles cannot be obtained as compared with a conventional ceramic or the like.
In addition, the thermal expansion coefficient of the diamond composite material is increased in spite of using two kinds of metals as the binder, and the difference in the thermal expansion coefficient from that of the semiconductor element is particularly increased. Therefore, other members such as semiconductor elements are easily damaged or disconnected from the connection surface due to expansion and contraction when a thermal history is applied.

On the other hand, when the volume ratio y of the diamond particles exceeds the above range, the total volume ratio of the two kinds of metals as the binder is relatively reduced, and the volume ratio of the binder described above is By increasing the processability, the effect of forming a connection surface that is excellent in smoothness and can be brought into close contact with other members without gaps by polishing in as short a time as possible.
On the other hand, by setting the volume ratio y of the diamond particles in the above range, it is possible to suppress an increase in the thermal expansion coefficient of the diamond composite material and to reduce the difference in the thermal expansion coefficient from the semiconductor element as much as possible. Become. Also, improve the workability while maintaining the thermal conductivity as high as possible, and form a connection surface that is excellent in smoothness and can adhere to other members such as semiconductor elements without gaps by polishing as short as possible Is possible.

In consideration of further improving this effect, the volume ratio y of the diamond particles is preferably 43% by volume or more, and more preferably 53% by volume or less even in the above range.
<Thermal characteristics>
(Coefficient of thermal expansion)
In the present invention, the thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is limited to 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ / K or less. Depending on the reason.

That is, when the thermal expansion coefficient of the diamond composite material is less than or exceeds this range, the difference in thermal expansion coefficient between the semiconductor element and the semiconductor element connected to the connection surface increases. Therefore, other members such as semiconductor elements are easily damaged or disconnected due to expansion and contraction when a thermal history is applied.
On the other hand, by setting the thermal expansion coefficient of the diamond composite material in the above range, the difference in thermal expansion coefficient between the semiconductor element connected to the connection surface can be made as small as possible. Accordingly, it is possible to prevent other members such as a semiconductor element from being damaged or disconnected from being expanded or contracted when a thermal history is applied.

In order to adjust the thermal expansion coefficient of the diamond composite material, the volume ratio y of the diamond particles can be changed within the range described above, or the volume ratio of the first metal and the second metal can be changed. Good.
The relationship between the volume ratio y 1 of the diamond particles and the volume ratio of the two metals and the coefficient of thermal expansion differs depending on the types of the two metals to be combined.

That is, in the combination in which the first metal is Cu and the second metal is Mo, the range surrounded by the solid line in FIG. 1, that is, the volume ratio y of the diamond particles is 40 volume% or more and 55 volume% or less. The volume ratio y of the diamond particles, and the volume ratio x of Mo in the total amount of Cu and Mo x = B / (A + B) × 100 [volume%, A is the volume% of Cu, and B is the volume% of Mo] , Formula (1) (2):
y ≧ −5.37x + 100 (1)
y ≦ −0.72x + 91 (2)
When the thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is in the range of 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ / K or less. be able to.

Similarly, in the combination in which the first metal is Cu and the second metal is W, the range surrounded by the solid line in FIG. 2, that is, the volume ratio y of the diamond particles is 40 volume% or more and 55 volume% or less. The volume ratio y of the diamond particles, and the volume ratio of W in the total amount of Cu and W x = B / (A + B) × 100 [volume%, A is the volume% of Cu, and B is the volume% of W] Equations (3) and (4):
y ≧ −5.37x + 100 (3)
y ≦ −0.92x + 101 (4)
When the thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is in the range of 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ / K or less. be able to.

In the combination in which the first metal is Ag and the second metal is Mo, the range surrounded by the solid line in FIG. 3, that is, the volume ratio y of the diamond particles is 40 volume% or more and 55 volume% or less. The volume ratio y of the diamond particles, and the volume ratio of Mo in the total amount of Ag and Mo x = B / (A + B) × 100 [volume%, A is the volume% of Ag, and B is the volume% of Mo] (5) (6):
y ≧ −0.74x + 49 (5)
y ≦ −1.33x + 127 (6)
When the thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is in the range of 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ / K or less. be able to.

Further, in the combination in which the first metal is Ag and the second metal is W, the range surrounded by the solid line in FIG. 4, that is, the volume ratio y of the diamond particles is 40% by volume or more and 55% by volume or less, The volume ratio y of the diamond particles, and the volume ratio of W in the total amount of Ag and W x = B / (A + B) × 100 [volume%, A is volume% of Ag, B is volume% of W], Equations (7) and (8):
y ≧ −0.74x + 49 (7)
y ≦ −0.83x + 102 (8)
When the thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is in the range of 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ / K or less. be able to.

In the present invention, the coefficient of thermal expansion of the diamond composite material is represented by a value measured using a differential thermal dilatometer.
(Thermal conductivity)
The degree of the thermal conductivity of the substrate for mounting a semiconductor element can be made not particularly limited by the configuration of the present invention, but the thermal conductivity is preferably 300 W / mK or more and 450 W / mK or less.

If the thermal conductivity of the semiconductor element mounting substrate is less than this range, the heat dissipation is insufficient, and the heat generated from the semiconductor element connected to the connection surface cannot be quickly dissipated through the semiconductor element mounting substrate. However, it may not be possible to prevent malfunction due to heat generation of itself.
On the other hand, even if it is the structure of this invention, it is difficult to provide high heat dissipation with the heat conductivity exceeding said range to the board | substrate for semiconductor element mounting.

On the other hand, by setting the thermal conductivity of the semiconductor element mounting substrate in the above range, the semiconductor element mounting substrate provides a high heat dissipation property, and the semiconductor element connected to the connection surface has its own. It is possible to further prevent operation failure due to heat generation.
In order to adjust the thermal conductivity, the volume ratio y 1 of the diamond particles and the volume ratio of the first metal and the second metal may be changed within the ranges described above.

In the present invention, the thermal conductivity of the substrate for mounting a semiconductor element is represented by a value measured by a laser flash method.
<Connection surface>
As described above, the substrate for mounting a semiconductor element according to the present invention has a larger amount of binder than the conventional one and is made of a diamond composite material with good workability. Therefore, the semiconductor element mounting substrate is connected to the substrate for mounting the semiconductor element. The connection surface with other members, such as the element mounting surface for heat treatment and the heat transfer surface for thermally connecting other heat dissipation members, is smooth and smooth with less time than before. It can be set as the surface excellent in property.

For example, in the surface polishing using a diamond grindstone of # 100 to # 400, the conventional method, which required only a rougher surface even if it takes about 20 hours, can be processed by processing for about 1 to 5 hours. There are no recesses and projections having a height of 10 to 40 μm and a maximum diameter in the surface direction of 10 μm or more and 3 mm or less, or the number of such recesses and projections per unit area of the connection surface. Can be a connection surface excellent in smoothness of 10 pieces / cm ² or less.

When the number of the concave portions and the convex portions exceeds the above range, there is a possibility that other members such as a semiconductor element cannot be adhered to the connection surface without a gap.
On the other hand, by setting the number of concave portions and convex portions in the above range, it is possible to improve the efficiency of heat conduction by connecting other members such as semiconductor elements in close contact with the connection surface without gaps. It becomes possible.

Needless to say, the lower limit of the number of concave and convex portions is 0 / cm ² . In other words, it is most preferable to have no concave portions and convex portions at all in order to improve the efficiency of heat conduction by bringing other members into close contact with each other without any gap. However, if the number of existing members is 10 pieces / cm ² or less, 0 pieces / cm. The same effect as in the case of ² can be achieved.
In the present invention, the number of such concave portions and convex portions was confirmed in the φ11 mm field of view using a microscope with a magnification of 20 at any 10 locations in the connection surface that define the number. The number of recesses and projections having the described depth or height and the maximum diameter in the surface direction is counted and expressed as an average value obtained by converting the number to the number per 1 cm ² .

According to the substrate for mounting a semiconductor element of the present invention, the arithmetic mean of the roughness curve defined in JIS B0601: 2001 is obtained by removing the region other than the concave portion and the convex portion of the connection surface by the above-described short-time planar polishing. A surface with excellent smoothness can also be obtained, with a roughness _Ra of 0.1 μm or more and 0.5 μm or less and a maximum height roughness _Rz of 1 μm or more and 5 μm or less.
When the arithmetic average roughness R _a and / or the maximum height roughness R _z exceed this range, there is a possibility that other members such as a semiconductor element cannot be closely adhered to the connection surface.

On the other hand, it is difficult to make the arithmetic average roughness R _a and / or the maximum height roughness R _z less than the above range, even in the configuration of the present invention, and it takes a long time for polishing. There is a possibility that the productivity of the substrate for mounting semiconductor elements decreases due to a decrease in manufacturing yield and the manufacturing cost increases.
On the other hand, by setting the arithmetic average roughness R _a and the maximum height roughness R _z in the above-described ranges, the productivity of the substrate for mounting the semiconductor element is improved, the manufacturing cost is reduced, and the semiconductor element, etc. It is possible to further improve the efficiency of heat conduction by bringing other members into close contact with each other without any gaps.

<Joint layer>
The connection surface is preferably covered with a bonding layer made of Au-Sn, In-Sn, or Au-Ge and made of lead-free solder or brazing material.
Such a bonding layer made of solder or brazing material is quickly melted by heating when connecting other members such as a semiconductor element or other heat radiating member to the connection surface, that is, the element mounting surface or the heat transfer surface, and the semiconductor element is It is excellent in that the strength of the connection is not greatly reduced or melted due to the thermal history during operation, and the thermal conductivity and the durability of the connection are improved.

The bonding layer preferably has a thickness of 1 μm or more, particularly 3 μm or more, preferably 10 μm or less, particularly preferably 7 μm or less, in the region other than the concave and convex portions on the connection surface.
If the thickness of the bonding layer is less than this range, the connection strength of other members such as a semiconductor element connected on the connection surface may be insufficient.
On the other hand, when the thickness of the bonding layer exceeds the above range, a large amount of solder or brazing material is interposed between the connected semiconductor element mounting substrate and other members, so that the thermal conductivity between the two May decrease.

The bonding layer can be formed by various conventionally known film forming methods such as vacuum deposition, sputtering, ion plating, chemical plating, and electroplating. In addition, the bonding layer may be formed by heating and melting a foil-shaped preform made of, for example, solder or brazing material on the connection surface.
<Adhesion layer>
It is preferable to provide an adhesion layer made of at least one metal selected from the group consisting of Ni, Au, Ti, and Cr between the connection surface and the bonding layer.

With the function of the adhesion layer, the adhesion of the bonding layer to the connection surface can be improved, and the strength of the connection of the other member connected on the bonding layer to the semiconductor element mounting substrate can be increased.
The adhesion layer preferably has a thickness of 0.01 μm or more in the region other than the concave and convex portions of the connection surface, and preferably 10 μm or less.
If the thickness of the adhesion layer is less than this range, the effect of forming the adhesion layer may not be obtained.

On the other hand, when the thickness of the adhesion layer exceeds the above range, the thermal conductivity between the connection surface and the other member may be reduced.
The adhesion layer can be formed by various conventionally known film forming methods such as vacuum deposition, sputtering, ion plating, chemical plating, and electroplating.
<Diffusion prevention layer>
It is preferable to provide a diffusion prevention layer made of at least one metal selected from the group consisting of Pt, Mo, and Pd between the adhesion layer and the bonding layer.

When a diffusion prevention layer is interposed between the two layers, when the bonding layer is melted by heating when connecting the semiconductor element to the element mounting surface or connecting another heat dissipation member to the heat transfer surface, By the function of the diffusion preventing layer, it is possible to prevent the metal from diffusing from the adhesion layer to the bonding layer and to prevent the composition of the solder or brazing material forming the bonding layer from being altered.
The diffusion preventing layer preferably has a thickness of 0.01 μm or more in the region other than the concave and convex portions in the connection surface, and preferably 1 μm or less.

If the thickness of the diffusion preventing layer is less than this range, the effect of forming the diffusion preventing layer may not be obtained.
On the other hand, when the thickness of the diffusion preventing layer exceeds the above range, the thermal conductivity between the connection surface and the other member may be reduced.
The diffusion preventing layer can be formed by various conventionally known film forming methods such as vacuum deposition, sputtering, ion plating, chemical plating, and electroplating.

<Semiconductor device>
In the present invention, the semiconductor element mounting substrate of the present invention described above is cut into a predetermined planar shape by laser processing or the like, if necessary, and then the semiconductor element is connected to the element mounting surface as a connection surface It is a semiconductor device.
In such a semiconductor device of the present invention, as described above, the semiconductor element can be connected to the element mounting surface in a state in which the semiconductor element is in close contact with, for example, a bonding layer. Therefore, the heat generated from the semiconductor element can be quickly radiated through the substrate for mounting the semiconductor element, and the semiconductor element is prevented from malfunctioning due to the heat generated by itself, for a longer period than before. It is possible to continue driving.

  Further, when the semiconductor element mounting substrate has a heat transfer surface together with the element mounting surface, for example, another heat radiating member such as a metal substrate is closely adhered to the heat transfer surface through the bonding layer. Since the connection can be made in a state, the heat generated from the semiconductor element can be radiated more quickly through the semiconductor element mounting substrate and the other heat radiating member. Therefore, the semiconductor element can be continuously driven for a longer period.

<Example 1-1>
Diamond particles having an average particle diameter of 40 μm, Cu powder having an average particle diameter of 3 μm (purity 99% or more, first metal), and Mo powder having an average particle diameter of 3 μm (purity 99% or more, second metal) A mixture in which the volume ratio of diamond particles in the total amount of components is 40.0% by volume, the volume ratio of Cu powder is 52.8% by volume, and the volume ratio of Mo powder is 7.2% by volume, After pre-molding under a press pressure of 196 MPa, it was sealed in a capsule made of molybdenum in a vacuum.

The volume ratio y of the diamond particles in the total amount of the three components was 40% by volume, and the volume ratio x of Mo in the total amount of Cu and Mo was 12% by volume.
Next, the capsule was heated under pressure for 5 minutes under the conditions of pressurization pressure: 5 GPa and heating temperature: 1100 ° C. Subsequently, the pressure was maintained, the temperature was lowered to room temperature and maintained for 30 minutes, and then returned to normal pressure. The capsule was recovered by returning.

The recovered capsule is ground to remove the molybdenum by removing the sintered body, and the taken-out sintered body is electrodischarge processed and cut into a plate shape. Then, one side of the plate is used with a # 140 diamond grindstone Surface polishing was performed for 2 hours to prepare a semiconductor element mounting substrate having a thickness of 0.3 mm as an element mounting surface.
<Examples 1-2 to 1-21>
Adjusting the volume ratio of diamond particles, Cu powder, and Mo powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of Mo in the total amount of Cu and Mo x ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 1-1 except that the volume%) was changed to the values shown in Tables 1 to 3.

<Comparative Examples 1-1 to 1-3>
Diamond particles having an average particle diameter of 40 μm and Cu powder having an average particle diameter of 3 μm (purity 99% or more) were blended at the values shown in Table 4 and the same as in Example 1-1 except that no Mo powder was blended. Thus, a semiconductor element mounting substrate having the same shape and the same dimensions was produced.
<Comparative Examples 1-4 to 1-22>
Adjusting the volume ratio of diamond particles, Cu powder, and Mo powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of Mo in the total amount of Cu and Mo x ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 1-1 except that (volume%) was set to the values shown in Tables 4 to 7.

The thermal expansion coefficient, thermal conductivity, depth or height of the element mounting surface of the semiconductor element mounting substrate produced in the examples and comparative examples is 10 to 40 μm, and the concave portion having a maximum surface direction diameter of 10 μm to 3 mm and Tables 1 to 7 show the arithmetic average roughness R _a and the maximum height roughness R _z of the roughness curve indicating the number of protrusions per unit area and the surface roughness in the regions outside the recesses and protrusions. Summarized.
The relationship between the volume ratio of diamond and the volume ratio of Cu and Mo in Examples and Comparative Examples is shown in FIG. In the figure, ○ indicates an example, and ● indicates a comparative example.

From the result of Comparative Example 1-3, in the conventional system using only Cu as the binder, workability is poor when the volume ratio of diamond particles is large, and smoothness is excellent in short-time polishing of about 2 hours. It was found that the connection surface could not be formed.
Further, from the results of Comparative Examples 1-1 and 1-2, when the volume ratio of the diamond particles is decreased, the workability is improved, and a contact surface having excellent smoothness can be formed by short-time polishing, but from 25 ° C. to 400 ° C. The coefficient of thermal expansion up to 5 ° C. is larger than 5.0 × 10 ⁻⁶ / K and not more than 8.5 × 10 ⁻⁶ K. ^Therefore , the thermal expansion is caused by expansion and contraction when a thermal history is applied. It has been found that other members such as semiconductor elements are easily damaged or disconnected from the connection surface.

  On the other hand, from the results of Examples 1-1 to 1-21 and Comparative Examples 1-4 to 1-22, the volume ratio of diamond particles is set to 40% by volume or more and 55% by volume or less, and the binder is first. Good processing is achieved by using both the metal Cu and the second metal Mo so that the coefficient of thermal expansion is in the above range, that is, the range surrounded by the solid line in FIG. It has been found that other members such as a semiconductor element can be prevented from being damaged or disconnected from the connection surface due to expansion and contraction when a heat history is applied while maintaining the heat characteristics.

<Example 2-1>
Diamond particles having an average particle diameter of 40 μm, Cu powder having an average particle diameter of 3 μm (purity 99% or more, first metal), and W powder having an average particle diameter of 3 μm (purity 99% or more, second metal) A mixture in which the volume ratio of diamond particles in the total amount of components is 40.0% by volume, the volume ratio of Cu powder is 52.8% by volume, and the volume ratio of W powder is 7.2% by volume, After pre-molding under a press pressure of 196 MPa, it was sealed in a capsule made of molybdenum in a vacuum.

The volume ratio y of diamond particles in the total amount of the three components was 40% by volume, and the volume ratio x of W in the total amount of Cu and W was 12% by volume.
Next, the capsule was heated under pressure for 5 minutes under the conditions of pressurization pressure: 5 GPa and heating temperature: 1100 ° C. Subsequently, the pressure was maintained, the temperature was lowered to room temperature and maintained for 30 minutes, and then returned to normal pressure. The capsule was recovered by returning.

The recovered capsule is ground to remove the molybdenum by removing the sintered body, and the taken-out sintered body is electrodischarge processed and cut into a plate shape. Then, one side of the plate is used with a # 140 diamond grindstone Surface polishing was performed for 2 hours to prepare a semiconductor element mounting substrate having a thickness of 0.3 mm as an element mounting surface.
<Examples 2-2 to 2-21>
By adjusting the volume ratio of diamond particles, Cu powder, and W powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of W in the total amount of Cu and W ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 2-1, except that (volume%) was set to the values shown in Tables 8 to 10.

<Comparative Examples 2-1 to 2-19>
By adjusting the volume ratio of diamond particles, Cu powder, and W powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of W in the total amount of Cu and W ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 2-1, except that (volume%) was set to the values shown in Tables 11 to 13.

The thermal expansion coefficient, thermal conductivity, depth or height of the element mounting surface of the semiconductor element mounting substrate produced in the examples and comparative examples is 10 to 40 μm, and the concave portion having a maximum surface direction diameter of 10 μm to 3 mm and Tables 8 to 13 show the arithmetic average roughness R _a and the maximum height roughness R _z of the roughness curves indicating the number of protrusions per unit area and the surface roughness in the regions outside the recesses and protrusions. Summarized.
The relationship between the volume ratio of diamond and the volume ratio of Cu and W in the examples and comparative examples is shown in FIG. In the figure, ○ indicates an example, and ● indicates a comparative example.

From the results of Examples 2-1 to 2-21 and Comparative Examples 2-1 to 2-19, the volume ratio of the diamond particles is set to 40% by volume or more and 55% by volume or less, and the binder is the first metal. A certain Cu and W, which is the second metal, have a thermal expansion coefficient in the range of 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ K or less, that is, a solid line in FIG. By using together so that it falls within the range surrounded by, other members such as semiconductor elements may be damaged or connected to the connection surface due to expansion and contraction when heat history is applied while maintaining good workability It has been found that it is possible to prevent from falling off.

<Example 3-1>
Diamond powder having an average particle size of 40 μm, Ag powder having an average particle size of 3 μm (purity 99% or more, first metal), and Mo powder having an average particle size of 3 μm (purity 99% or more, second metal) A mixture in which the volume ratio of diamond particles in the total amount of components is 40.0% by volume, the volume ratio of Ag powder is 47.5% by volume, and the volume ratio of Mo powder is 12.5% by volume, After pre-molding under a press pressure of 196 MPa, it was sealed in a capsule made of molybdenum in a vacuum.

The volume ratio y of the diamond particles in the total amount of the three components was 40% by volume, and the volume ratio x of Mo in the total amount of Ag and Mo was 21% by volume.
Next, the capsule was heated under pressure for 5 minutes under the conditions of pressurization pressure: 5 GPa and heating temperature: 1100 ° C. Subsequently, the pressure was maintained, the temperature was lowered to room temperature and maintained for 30 minutes, and then returned to normal pressure. The capsule was recovered by returning.

The recovered capsule is ground to remove the molybdenum by removing the sintered body, and the taken-out sintered body is electrodischarge processed and cut into a plate shape. Then, one side of the plate is used with a # 140 diamond grindstone Surface polishing was performed for 2 hours to prepare a semiconductor element mounting substrate having a thickness of 0.3 mm as an element mounting surface.
<Examples 3-2 to 3-21 >
Adjusting the volume ratio of diamond particles, Ag powder, and Mo powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of Mo in the total amount of Ag and Mo x ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 3-1, except that (volume%) was set to the values shown in Tables 14 to 17.

<Comparative Examples 3-1 to 3-3>
Diamond particles having an average particle diameter of 40 μm and Ag powder having an average particle diameter of 3 μm (purity 99% or more) were blended at the values shown in Table 18, and the same procedure as in Example 3-1 except that no Mo powder was blended. Thus, a semiconductor element mounting substrate having the same shape and the same dimensions was produced.
<Comparative Examples 3-4 to 3-22>
Adjusting the volume ratio of diamond particles, Ag powder, and Mo powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of Mo in the total amount of Ag and Mo x ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 3-1, except that (volume%) was set to the values shown in Table 18 to Table 21.

The thermal expansion coefficient, thermal conductivity, depth or height of the element mounting surface of the semiconductor element mounting substrate produced in the examples and comparative examples is 10 to 40 μm, and the concave portion having a maximum surface direction diameter of 10 μm to 3 mm and Tables 14 to 21 show the arithmetic average roughness R _a and the maximum height roughness R _z of the roughness curves indicating the number of protrusions per unit area and the surface roughness in the regions outside the recesses and protrusions. Summarized.
The relationship between the volume ratio of diamond and the volume ratio of Ag and Mo in Examples and Comparative Examples is shown in FIG. In the figure, ○ indicates an example, and ● indicates a comparative example.

From the result of Comparative Example 3-3, in a conventional system using only Ag as a binder, workability is poor when the volume ratio of diamond particles is large, and smoothness is excellent in short-time polishing of about 2 hours. It was found that the connection surface could not be formed.
Further, from the results of Comparative Examples 3-1 and 3-2, when the volume ratio of the diamond particles is reduced, the workability is improved, and a contact surface with excellent smoothness can be formed by short-time polishing, but from 25 ° C. to 400 ° C. The coefficient of thermal expansion up to 5 ° C. is larger than 5.0 × 10 ⁻⁶ / K and not more than 8.5 × 10 ⁻⁶ K. ^Therefore , the thermal expansion is caused by expansion and contraction when a thermal history is applied. It has been found that it is impossible to prevent other members such as semiconductor elements from being damaged or from being disconnected from the connection surface.

On the other hand, from the results of Examples 3-1 to 3-21 and Comparative Examples 3-4 to 3-22, the volume ratio of the diamond particles is set to 40% by volume or more and 55% by volume or less, and the binder is first. By using together Ag, which is the metal of the second metal, and Mo, which is the second metal, so that the thermal expansion coefficient is in the above range, that is, within the range surrounded by the solid line in FIG. It has been found that other members such as a semiconductor element can be prevented from being damaged or disconnected from the connection surface due to expansion and contraction when a heat history is applied while maintaining the heat characteristics.

<Example 4-1>
Diamond powder having an average particle diameter of 40 μm, Ag powder having an average particle diameter of 3 μm (purity 99% or more, first metal), and W powder having an average particle diameter of 3 μm (purity 99% or more, second metal) A mixture in which the volume ratio of diamond particles in the total amount of the components is 40.0% by volume, the volume ratio of Ag powder is 47.5% by volume, and the volume ratio of W powder is 12.5% by volume, After pre-molding under a press pressure of 196 MPa, it was sealed in a capsule made of molybdenum in a vacuum.

The volume ratio y of diamond particles in the total amount of the three components was 40% by volume, and the volume ratio x of W in the total amount of Ag and W was 21% by volume.
Next, the capsule was heated under pressure for 5 minutes under the conditions of pressurization pressure: 5 GPa and heating temperature: 1100 ° C. Subsequently, the pressure was maintained, the temperature was lowered to room temperature and maintained for 30 minutes, and then returned to normal pressure. The capsule was recovered by returning.

The recovered capsule is ground to remove the molybdenum by removing the sintered body, and the taken-out sintered body is electrodischarge processed and cut into a plate shape. Then, one side of the plate is used with a # 140 diamond grindstone Surface polishing was performed for 2 hours to prepare a semiconductor element mounting substrate having a thickness of 0.3 mm as an element mounting surface.
<Examples 4-2 to 4-23>
By adjusting the volume ratio of diamond particles, Ag powder, and W powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of W in the total amount of Ag and W x ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 4-1, except that (volume%) was set to the values shown in Tables 22 to 25.

<Comparative Examples 4-1 to 4-19>
By adjusting the volume ratio of diamond particles, Ag powder, and W powder, the volume ratio y (volume%) of diamond particles in the total amount of the three components, and the volume ratio x of W in the total amount of Ag and W x ( A substrate for mounting a semiconductor element having the same shape and the same dimensions was produced in the same manner as in Example 4-1, except that (volume%) was set to the values shown in Tables 26 to 28.

The thermal expansion coefficient, thermal conductivity, depth or height of the element mounting surface of the semiconductor element mounting substrate produced in the examples and comparative examples is 10 to 40 μm, and the concave portion having a maximum surface direction diameter of 10 μm to 3 mm and Tables 22 to 28 show the arithmetic average roughness R _a and the maximum height roughness R _z of the roughness curve indicating the number of protrusions per unit area and the surface roughness in the regions outside the recesses and protrusions. Summarized.
The relationship between the volume ratio of diamond and the volume ratio of Ag and W in the examples and comparative examples is shown in FIG. In the figure, ○ indicates an example, and ● indicates a comparative example.

From the results of Examples 4-1 to 4-23 and Comparative Examples 4-1 to 4-19, the volume ratio of the diamond particles is set to 40% by volume or more and 55% by volume or less, and as the binder, the first metal is used. A certain Ag and W, which is the second metal, have a coefficient of thermal expansion in the range of 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ K or less, that is, a solid line in FIG. By using together so that it falls within the range surrounded by, other members such as semiconductor elements may be damaged or connected to the connection surface due to expansion and contraction when heat history is applied while maintaining good workability It has been found that it is possible to prevent from falling off.

Claims (11)

It consists of a diamond composite material in which a large number of diamond particles are bound together by a binder,
Having a connection surface with other members,
The binder is
(A) Cu as the first metal , and
(B) Mo as the second metal
Of the two types,
The volume ratio of the diamond particles occupying in the total amount of the two metals and the diamond particles y, wherein the volume ratio of the Mo occupied in the total amount of the two metals x = B / (A + B ) × 100 [vol %, A is Cu volume%, and B is Mo volume%], the volume ratio y is 40 volume% or more and 55 volume% or less, and
Said x and y are the formulas (1) and (2):
y ≧ −5.37x + 100 (1)
y ≦ −0.72x + 91 (2)
Satisfied,
The thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is 5.0 × 10 ⁻⁶ / K or more and 8.5 × 10 ⁻⁶ K or less.
A substrate for mounting semiconductor elements. It consists of a diamond composite material in which a large number of diamond particles are bound together by a binder,
Having a connection surface with other members,
The binder is
(A) Cu as the first metal, and
(B) W as the second metal
Of the two types,
The volume ratio of the diamond particles in the total amount of the diamond particles and the two metals is y, and the volume ratio of W in the total amount of the two metals is x = B / (A + B) × 100 [volume. %, A is Cu volume%, and B is W volume%], the volume ratio y is 40 volume% or more and 55 volume% or less, and
Said x and y are formulas (3) and (4):
y ≧ −5.37x + 100 (3)
y ≦ −0.92x + 101 (4)
Satisfied,
The thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is 5.0 × 10 ^-6 / K or more, 8.5 × 10 ^-6 K or less,
A substrate for mounting semiconductor elements. It consists of a diamond composite material in which a large number of diamond particles are bound together by a binder,
Having a connection surface with other members,
The binder is
(A) Ag as the first metal, and
(B) Mo as the second metal
Of the two types,
The volume ratio of the diamond particles in the total amount of the diamond particles and the two metals is y, and the volume ratio of Mo in the total amount of the two metals is x = B / (A + B) × 100 [volume. %, A is volume% of Ag, and B is volume% of Mo], the volume ratio y is 40 volume% or more and 55 volume% or less, and
Said x and y are formulas (5) and (6):
y ≧ −0.74x + 49 (5)
y ≦ −1.33x + 127 (6)
Satisfied,
The thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is 5.0 × 10 ^-6 / K or more, 8.5 × 10 ^-6 K or less,
A substrate for mounting semiconductor elements. It consists of a diamond composite material in which a large number of diamond particles are bound together by a binder,
Having a connection surface with other members,
The binder is
(A) Ag as the first metal, and
(B) W as the second metal
Of the two types,
The volume ratio of the diamond particles in the total amount of the diamond particles and the two metals is y, and the volume ratio of W in the total amount of the two metals is x = B / (A + B) × 100 [volume. %, A is volume% of Ag, and B is volume% of W], the volume ratio y is 40 volume% or more and 55 volume% or less, and
Said x and y are formulas (7) (8):
y ≧ −0.74x + 49 (7)
y ≦ −0.83x + 102 (8)
Satisfied,
The thermal expansion coefficient from 25 ° C. to 400 ° C. of the diamond composite material is 5.0 × 10 ^-6 / K or more, 8.5 × 10 ^-6 K or less,
A substrate for mounting semiconductor elements. The connection surface does not have a recess or a protrusion having a depth or height of 10 to 40 μm and a maximum diameter in the surface direction of 10 μm or more and 3 mm or less, or the unit of the connection surface of the recess and the protrusion The semiconductor element mounting substrate according to any one of claims 1 to 4, wherein the number of existence per area is 10 pieces / cm ² or less. The arithmetic mean roughness Ra of the roughness curve indicating the surface roughness of the connection surface in the region other than the concave and convex portions is 0.1 μm or more and 0.5 μm or less, and the maximum height roughness Rz is 1 μm. The substrate for mounting a semiconductor element according to claim 5 , wherein the substrate is 5 μm or less. Thermal conductivity, 300 W / mK, the semiconductor element mounting board according to any one of claims 1 to 6 or less 450 W / mK. It said connecting surface, Au-Sn-based semiconductor according to any one of In-Sn-based or Au-Ge-based claims are covered by the bonding layer made of solder or braze to claim 1 to claim 7, Device mounting board. 9. The semiconductor element mounting according to claim 8 , wherein an adhesion layer made of at least one metal selected from the group consisting of Ni, Au, Ti, and Cr is provided between the connection surface and the bonding layer. Substrate. 10. The semiconductor element mounting device according to claim 9 , wherein a diffusion prevention layer made of at least one metal selected from the group consisting of Pt, Mo, and Pd is provided between the adhesion layer and the bonding layer. substrate. Claim 1 in connection surface of the semiconductor element mounting board according to any one of claims 10, semiconductor element device in which a semiconductor element is connected.

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