JP2001024102A - Case for semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a case for a semiconductor wherein a heat sink part where a semiconductor element is mounted and a circular base part which supports the heat sink part are integrally molded while a cap can be directly welded to the circular base part, with thermal expansion factor and heat transfer coefficient being stable for long-term reliability of a semiconductor element. SOLUTION: A heat sink 104 on which a semiconductor element 102 is mounted, a circular base 105 which supports the heat sink 104, and a cap 106 which covers the heat sink 104 and the semiconductor element 102 and jointed to the circular base 105 to form a closed space, are provided. Here, the heat sink 104 and the circular base 105 comprise an alloy wherein an integral mold of a mixed powder where tungsten powder and other metal powder are agitated and mixed is baked with a heavy alloy mechanism theory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor case for housing a semiconductor element used for optical transmission or the like.

[0002]

2. Description of the Related Art Laser diodes and light emitting diodes,
GaAs, GaP, InAs, and GaSb compound semiconductor elements that emit electromagnetic waves, such as power transistors, FET elements (field effect transistors), and microwave communication devices, deteriorate by themselves and lose long-term reliability due to heat generated by the generation of electromagnetic waves. Sometimes. In order to prevent this deterioration and ensure long-term reliability, the semiconductor element is used by being housed in a semiconductor case. 6 and 7 show a conventional semiconductor case. The semiconductor case is supported by the submount 3 on which the semiconductor element 2 is mounted, the heat sink member 4 supporting the submount 3, the circular base 5 supporting the heat sink member 4, and the circular base 5. The circular base 5 covers the heat sink member 4 and the submount 4 on which the semiconductor element 2 is mounted.
6 that is welded to the head to form a closed space
It consists of The light extraction window 7 is mounted on the upper surface of the cap. The semiconductor case thus configured is used in a state where nitrogen gas or the like is sealed in the above-mentioned closed space and the semiconductor element is isolated from the outside air. In the drawings, reference numerals 8 and 9 denote lead wires mounted on the circular base 5 via an insulating member 10, and reference numeral 11 denotes a lead wire connecting one of the lead wires 8 to the semiconductor element 2.

It is desirable that the semiconductor case described above efficiently radiates heat generated from the semiconductor element 2 such as a laser diode or a light emitting diode. On the other hand, if there is a difference in the coefficient of thermal expansion between the semiconductor element 2 and the submount 3 on which the semiconductor element 2 is mounted, distortion occurs due to heat generation, and unnecessary stress is applied to the semiconductor element 2. Such stress accelerates performance deterioration of the semiconductor element 2 and further causes destruction. Accordingly, the material of the submount 2 is required to have a coefficient of thermal expansion close to the coefficient of thermal expansion of the semiconductor element, and the heat sink member 4 and the circular substrate 5 are required to have a material having a high thermal conductivity. In order to satisfy such a demand, in a conventional semiconductor case, the submount 3 is made of, for example, alumina or aluminum nitride having a coefficient of thermal expansion close to that of the semiconductor element 2, and the heat sink member 4 is made of copper or the like having good thermal conductivity. Generally, a member made of silver or the like and the circular base 5 made of a weldable iron material is used. However, in the above-described semiconductor case, since the materials of the submount 3, the heat sink member 4, and the circular base 5 are different from each other, they must be brazed with a brazing material such as silver brazing or Au-Sn alloy in order to combine them. Therefore, there is a problem that productivity is low and the cost is high. In addition, it has been pointed out that the above-described semiconductor case has a problem that the thermal expansion coefficient and the thermal diffusion become unstable due to the brazing material, so that long-term reliability of the semiconductor element cannot be obtained.

[0004] In order to solve the above-mentioned problem, a composite in which the above-mentioned submount, heat sink member and circular base are impregnated with copper by a molten metal infiltration method (infiltration method) in either tungsten or molybdenum or a tungsten-molybdenum alloy. A semiconductor case made of a material is disclosed in, for example, Japanese Patent Publication No. 242392/1990 and Japanese Patent Publication No.
No. 4393. This composite material is formed by forming tungsten or molybdenum or a powder of tungsten and molybdenum into a plate, sintering it to form a network structure, and placing a high-purity copper plate on the network structure. By heating at a temperature of about 1200 ° C., copper is melted and permeated into the network structure to produce the copper.
Further, there is also a technology in which a mixed powder of tungsten powder and copper powder is formed into a predetermined shape, and a heat sink member and a circular base are integrally formed by a tungsten-copper pseudo-alloy obtained by sintering the formed body formed into the predetermined shape. Proposed.

[0005]

However, the composite material and the tungsten-copper pseudo-alloy manufactured by the above-described infiltration method are difficult to weld with an iron-based metal. Is formed of the above-mentioned composite material or tungsten-copper pseudo-alloy, a cap formed of an iron-based metal cannot be directly joined to a circular base by welding. Therefore, an iron-based metal material such as Kovar is previously brazed to the circular base with a brazing agent such as silver wax, and a cap formed of an iron-based metal is joined to the iron-based metal material by laser welding. I have. As described above, in the case where the circular base portion is formed of the composite material or the tungsten-copper pseudo-alloy, it is necessary to braze an iron-based metal material in advance in order to weld the cap. The productivity cannot be increased due to the increase. Also,
Since the above-mentioned composite material or tungsten-copper pseudo-alloy has a structure in which copper is taken in a mesh structure of tungsten, the density is not always uniform, and the coefficient of thermal expansion and the coefficient of thermal conductivity vary depending on the location. There is a problem that quality is not stable and reliability is lacking.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its main technical problem is that a heat sink portion for mounting a semiconductor element and a circular base portion for supporting the heat sink portion can be integrally formed. It is an object of the present invention to provide a semiconductor case that can be directly welded to a circular base portion, and has a stable coefficient of thermal expansion and thermal conductivity and can obtain long-term reliability of a semiconductor element.

[0007]

According to the present invention, there is provided a heat sink for mounting a semiconductor element, a circular base for supporting the heat sink, and a heat sink for mounting the heat sink. A cap covering the semiconductor element and joining to the circular base to form a sealed space, wherein the heat sink and the circular base are made of tungsten-based powder and other metal powder. And a molded body integrally formed from a mixed powder obtained by stirring and mixing the above-mentioned components with an alloy sintered by a heavy alloy mechanism theory.

[0008] The tungsten-based powder is either a tungsten powder or a molybdenum powder, or a mixed powder containing either a tungsten powder or a molybdenum powder as a main component, and the other metal powder includes a nickel powder. The weight ratio of the tungsten powder is 85 to 98.
%, The weight ratio of molybdenum powder is 0 to 12%, the weight ratio of nickel powder is 1 to 12%, the weight ratio of copper powder is 0 to 5%, and the weight ratio of iron powder is 0%. ~ 5%
The weight ratio of the cobalt powder is 0 to 5%, and the powder mixture is made of a mixed powder mixed at an appropriate ratio so that the total weight ratio becomes 100%. In this mixed powder, "0% by weight of copper powder, 0% by weight of iron powder" or "0% by weight of copper powder, 1% or less by weight of iron powder, 0.1 to 0.1% by weight of molybdenum powder" 8% and / or 0.1 to 5% by weight of cobalt powder. "

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a semiconductor case constructed according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing an embodiment of a semiconductor case constructed according to the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. The semiconductor case in the illustrated embodiment includes a heat sink 104 having a mount 103 on which the semiconductor element 102 is mounted,
Circular base 105 supporting heat sink 104
However, it is composed of an alloy obtained by sintering a compact formed into a predetermined shape with a mixed powder obtained by stirring and mixing a tungsten-based powder and another metal powder by a heavy alloy mechanism theory. The heat sink 104 and the circular base 105 will be described in more detail. Tungsten (W) powder: 85 to 98% by weight, molybdenum (Mo) powder: 0 to 12% by weight, nickel (Ni) powder; % By weight, copper (Cu) powder;
0 to 5% by weight of iron (Fe) powder and 0 to 5% by weight of cobalt (Co) powder are mixed in an appropriate ratio, and a lubricant or a lubricant and a binder are added thereto and mixed with a blender or a kneader. Then, the mixed powder is molded into a predetermined shape by compression molding or injection molding to obtain a molded body. The molded body is fired at a temperature of 1350 to 1700 ° C. for about 1 hour in a substantially vacuum atmosphere or a substantially reducing gas or an inert atmosphere, thereby forming a heat sink portion 104 having a predetermined shape and a circular base portion. 105 can be made in one piece. Note that “0% by weight” of each of the above powders does not have an absolute meaning that no unavoidable impurities are contained.

The mounting section 1 of the heat sink section 104
03 that covers the semiconductor element 102 mounted on the substrate 03
6 is made of an iron-based metal in the illustrated embodiment, and has a light extraction window 107 on the upper surface. Nitrogen gas or the like is sealed in a closed space covered by the cap 106 and the circular base 105. The outer periphery of the mounting portion 106a of the cap 106 is mounted on the circular base portion 105 by laser welding. That is,
Since the circular base 105 made of the above alloy can be welded, the cap 10 made of an iron-based metal is used.
6 can be directly welded to the circular base 105.
In the drawing, reference numerals 108 and 109 denote lead wires mounted on the circular base portion 105 via an insulating member 110, and reference numeral 111 denotes a lead wire connecting one of the lead wires 108 to the semiconductor element 102. The semiconductor element 102 is mounted on the mounting portion 10 of the heat sink 104 as in the illustrated embodiment.
Although it is desirable to mount the device directly on the heat sink portion 104, it may be mounted on a submount member made of alumina, aluminum nitride, or the like due to a problem in handling the semiconductor element, and mounted on the mount portion 103 of the heat sink portion 104 in a submount state. .

FIGS. 3 to 5 show a heat sink 104 having a mount 103 on which the semiconductor element 102 is mounted.
And a circular base 1 supporting the heat sink 104
No. 05 shows an example in which a molded body formed into a predetermined shape by the above-mentioned alloy, that is, a mixed powder obtained by stirring and mixing a tungsten-based powder and another metal powder, is integrally molded with an alloy sintered by the heavy alloy mechanism theory. It is a perspective view. FIG. 3 shows a heat sink part 1 having a circular base part 105 having a lead wire hole 105 a and a mount part 103.
04 are integrally formed. FIG. 4 shows that a circular base 105 having a lead wire hole 105a and a heat sink 104 having a mount 103 are integrally formed, and a semiconductor is provided immediately below the mount 103 in the circular base 105. A concave portion 10 for irregularly reflecting and extinguishing unnecessary laser light emitted from the rear portion of the laser.
5b is integrally formed. FIG. 5 shows a heat sink unit 10 having a circular base portion 105 having a lead wire hole 105a and a projecting mount portion 103.
4 are integrally formed. It is to be noted that the molded body may be subjected to post-processing as needed, and may be freely adapted to the mode of use.

As described above, in the semiconductor case constructed in accordance with the present invention, the heat sink portion 104 and the circular base portion 105 are formed into a predetermined shape by a mixed powder obtained by stirring and mixing a tungsten-based powder and another metal powder. It is important that the compact formed is made of an alloy sintered according to the heavy alloy mechanism theory. Here, the heavy alloy mechanism theory is defined. The heavy alloy mechanism theory is that a metal powder (for example, 90% by weight of tungsten powder, 7.5% by weight of nickel powder, and 2.5% by weight of copper powder) is mixed into a predetermined shape with a mixed powder. For example, the molded body is 1
When sintering at a temperature of 350 to 1700 ° C., some solid particles dissolve to form a liquid phase, but metal powder having a high melting point such as tungsten has a limit in dissolving solid particles,
The melting and precipitation phenomena are repeated during sintering, and the density of the sintered body is increased while the solid particles undergo grain growth called Ostwald ripening. When this grain growth continues for about one hour,
Finally, it refers to a phenomenon in which solid particles come into contact with each other and solid phase diffusion occurs, and sintering proceeds to near the theoretical density to form an alloy.

Table 1 shows a compact formed from a mixed powder containing tungsten (W) powder as a main component (85 to 97% by weight) and other metal powders mixed at an appropriate ratio.
3 shows the thermal conductivity (W / mK) and the coefficient of thermal expansion (× 10 −6 / ° C.) of an alloy sintered according to the heavy alloy mechanism theory. The corrosion resistance is a result of performing a salt spray test for 24 hours.

[0015]

[Table 1]

An alloy obtained by sintering a compact formed from the above-mentioned mixed powder of the tungsten-based powder and another metal powder by the heavy alloy mechanism theory has a coefficient of thermal expansion of 5.23 to 7.05) × 10−. In the range of 6 / ° C, the thermal expansion coefficient of GaP constituting the semiconductor device (5.3 × 10−6 / ° C)
C), thermal expansion coefficient of InAs (5.8 × 10 −6 / ° C.), Ga
The thermal expansion coefficient of As (6.5 × 10 −6 / ° C.) and the thermal expansion coefficient of GaSb (6.9 × 10 −6 / ° C.)
Alumina (15 W) having a thermal conductivity of 67 to 129 (W / mK) and a thermal expansion coefficient close to that of the compound semiconductor element
/ MK) and 5-8 times the thermal conductivity of Kovar (15 W / mK), and has characteristics required for a heat sink material for semiconductors. In addition, since the sintered alloy is a dense alloy and does not form voids unlike the composite material and the tungsten-copper pseudo-alloy, the coefficient of thermal expansion and the coefficient of thermal conductivity are not uniform in some places. However, stable heat sink characteristics can be ensured. Further, since the sintered alloy can be welded to an iron-based metal, the cap formed of the iron-based metal can be directly welded to the circular base.

As shown in Table 1, "0% by weight of copper (Cu) powder, 0% by weight of iron (Fe) powder" or "0% by weight of copper (Cu) powder, 0% by weight of iron (Fe) ) Powder weight ratio 1% or less, molybdenum (Mo) powder weight ratio 0.1 to
8% and / or a weight ratio of cobalt (Co) powder of 0.1 to 5% "does not cause rust, and therefore, the heat sink portion and the circular base portion should be manufactured from this sintered alloy. Thereby, a semiconductor case excellent in corrosion resistance can be obtained. Rust is observed in alloys other than those described above, but in the case where the alloy forms a heat sink portion and a circular base portion, the alloy is subjected to a rust-proof treatment such as plating or metal deposition to provide corrosion resistance. It is desirable to improve.

The alloy sintered according to the heavy alloy mechanism theory shown in Table 1 is an example in which tungsten (W) powder is the main component as the tungsten-based powder, and molybdenum (Mo) powder is the main component as the tungsten-based powder. Alternatively, the heat sink portion and the circular base portion may be formed using an alloy sintered according to the heavy alloy mechanism theory.

[0019]

Since the semiconductor case according to the present invention is constituted as described above, the following operation and effect can be obtained.

That is, according to the present invention, the heat sink portion and the circular base portion constituting the semiconductor case are formed of a molded body integrally formed of a mixed powder obtained by stirring and mixing a tungsten-based powder and another metal powder. It is made of an alloy sintered according to the heavy alloy mechanism theory, and since this sintered alloy can be welded with an iron-based metal, a cap formed of an iron-based metal is directly welded to a circular base. be able to. Therefore, since it is not necessary to braze the iron-based metal material in advance to weld the cap, productivity can be improved, and an inexpensive semiconductor case can be obtained. In addition, the sintered alloy has a dense and dense structure, and does not generate voids unlike the composite material and the tungsten-copper pseudo alloy,
A highly reliable semiconductor case with uniform thermal expansion coefficient and thermal conductivity, good dimensional accuracy, can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor case configured according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a perspective view showing an embodiment in which a heat sink portion provided with a mount portion and a circular base portion constituting a semiconductor case according to the present invention are integrally formed of a sintered alloy.

FIG. 4 is a perspective view showing another embodiment in which a heat sink portion provided with a mount portion and a circular base portion constituting a semiconductor case according to the present invention are integrally formed of a sintered alloy.

FIG. 5 is a perspective view showing still another embodiment in which a heat sink portion provided with a mount portion and a circular base portion constituting a semiconductor case according to the present invention are integrally formed of a sintered alloy.

FIG. 6 is a plan view of a conventionally used semiconductor case.

FIG. 7 is a sectional view taken along line BB in FIG. 6;

[Explanation of symbols]

 102: Semiconductor element 104: Heat sink 105: Circular base 106: Cap 107: Light extraction window 108, 109: Lead wire 110: Insulating member 111: Lead wire

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01S 5/022 H01L 23/36 M (72) Inventor Teruaki Maehata 3-25-21 Higashishinagawa, Shinagawa-ku, Tokyo Stock Company Inside Technisco (72) Inventor Takuma Kishida 3-25-21 Higashishinagawa, Shinagawa-ku, Tokyo Stock Company Inside Technisco Company (72) Inventor Satoshi 3-25-21 Higashishinagawa, Shinagawa-ku, Tokyo Stockholm Company F-term (Reference) 4K018 AA19 BA04 BA09 KA32 5F036 AA01 BB09 BD01 5F073 BA02 DA35 FA15

Claims (4)

[Claims] 1. A heat sink for mounting a semiconductor element, a circular base for supporting the heat sink, and a cap for covering the heat sink and the semiconductor element and joining to the circular base to form a sealed space. Wherein the heat sink portion and the circular base portion are formed by integrally molding a compact formed by mixing and mixing a tungsten-based powder and another metal powder with a heavy alloy mechanism. A case for a semiconductor, comprising an alloy sintered in theory. 2. The tungsten-based powder is either a tungsten powder or a molybdenum powder, or a mixed powder mainly containing either a tungsten powder or a molybdenum powder, and the other metal powder is a nickel powder. Claim 1.
The semiconductor case as described in the above. 3. The weight ratio of said tungsten powder is 85-9.
8%, the weight ratio of molybdenum powder is 0 to 12%, the weight ratio of nickel powder is 1 to 12%, the weight ratio of copper powder is 0 to 5%, and the weight ratio of iron powder is 0-5%
The case for a semiconductor according to claim 2, wherein the weight ratio of the cobalt powder is 0 to 5%, and the mixed powder is mixed at an appropriate ratio so that the total of the weight ratio becomes 100%. 4. A weight ratio of copper powder of 0% and a weight ratio of iron powder of 0% or a weight ratio of copper powder of 0% and a weight ratio of iron powder of 1
%, The weight ratio of molybdenum powder is 0.1 to 8%, and / or the weight ratio of cobalt powder is 0.1 to 5% ”.