JPH0236553A - Connection structure between components for semiconductor device - Google Patents

Abstract

PURPOSE:To offer a highly reliable connection structure between components for semiconductor device use by a method wherein a buffer material is formed into a three-layer structure, which consists of soft metal layers consisting of a soft metal material having a high plastic deformation power and a metal layer, which is pinched by the soft metal layers and contains at least one metal of molybdenum and tungsten. CONSTITUTION:A metallized layer 2 is formed on part of the surface of a substrate 1 consisting of Al nitride and lead frames 3 are soldered to this layer 2 with a metal solder or the like and the layer 2 and the frames 3 are bonded to each other. A buffer material with a nickel-plated layer formed on its surface is interposed between the layer 2 and the frames 3. This material has a three- layer structure, which consists of soft metal layers consisting of copper or the like and a molybdenum or tungsten-containing metal layer pinched by the soft metal layers. Moreover, a semiconductor element 4 of a high-calorific value FET and the like is mounted at a prescribed position on the Al nitride substrate 1 and is connected with the layer 2 or the frames 3 by bonding wires 5.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a connection structure between parts of a semiconductor device, and is particularly suitable for mounting semiconductor elements with high heat generation, such as high power transistors, laser diodes, etc. The present invention relates to a connection structure between parts of a semiconductor device that requires high thermal conductivity.

[Prior Art] A connection structure between parts for a semiconductor device configured to mount a semiconductor element is generally composed of an insulating base material and a joining member joined to the insulating base material.

- For example, the connection structure includes an insulating substrate on which a semiconductor element is placed, and a predetermined portion on which a wiring circuit is formed on the insulating substrate by soldering using silver solder or the like. It consists of a lead frame or a heat sink connected to the insulating substrate by soldering using silver solder or the like. In this case, the insulating substrate is generally required to have electrical insulation and mechanical strength to maintain insulation from the semiconductor element, and high thermal conductivity to dissipate heat generated from the semiconductor element. Furthermore, the lead frame is required to have low electrical resistance and high mechanical strength. Furthermore, the heat sink is required to have high thermal conductivity.

Connection structures between such semiconductor device parts, for example,
Alumina (ALO3) has traditionally been used as a material for insulating substrates used in semiconductor device packages, electronic components, etc.
is generally selected as satisfying the above characteristics. Further, various metal materials to be connected to the insulating base include the following. For example, in the case of lead frames and [,], the product name Kovar (Fe-29 Ni-17 weight% Co
alloy), 4270i (Fe-42 wt% Ni alloy)
Generally, iron-nickel alloys such as iron-nickel alloys are selected.

As a heat sink, a copper-tungsten alloy (W-10 to 20 heavy FF19) that satisfies the above characteristics is used.
6 Cu alloy) is commonly selected. [Chemical Industry J March 1984 issue special feature on electroceramics, “
As disclosed in Ceramic Substrates and IC Pancage JP, 59-67, a metallized layer formed as a wiring circuit on an insulating substrate made of alumina is coated with a lead frame made of Kovar (trade name) or silver solder. A brazed connection structure is used on a substrate for mounting a semiconductor device.

FIG. 4A is a plan view showing an example of a conventional connection structure between components for a semiconductor device having the above-described configuration, FIG. 4B is a cross-sectional view thereof, and FIG. 4C is a diagram showing a lead frame 3 and a substrate 1 made of alumina. FIG.

In the figure, the connection structure between parts for this "f-conductor device" is such that a metallized layer 2 is formed on a part of the surface of a substrate 1 made of alumina.
is formed, and a lead frame 3 is bonded to this metallized layer 2 by brazing with metal solder or the like. Further, at a predetermined position 1u of the bracket 1, a semiconductor wire 4 such as a high heat generating field effect transistor (CFET) is mounted and connected to the metallized layer 2 or the lead frame 3 with a bonding wire 5. Further, a heat sink 6 made of a tungsten alloy, for example a copper-tungsten alloy, is attached to the back surface of the substrate 1. Further, as shown in FIG. 4C, at the joint between the substrate 1 and the lead frame 3, a thin plating layer 7 is formed on the metallized layer 2, and the surface of the lead frame 3 has a wettability of the metal solder 9. In order to stabilize
A plating layer 8 is formed as necessary.

In addition, as another example of a connection structure between parts for a semiconductor device,
Examples include a cap for hermetically sealing a semiconductor element mounted on an insulating substrate.

The materials used for caps for sealing semiconductor devices, which require a high level of reliability, include low thermal expansion alloy materials such as 42 Alloy and Kovar (trade name), or ceramic materials such as alumina and mullite.

Its structure is as shown in FIGS. 5A and 5B. That is, in the figure, the semiconductor element 4 is mounted on a ceramic substrate 101, and the cover member 11 is placed over this. Particularly, when the cover member 11 is made of insulating ceramics, that is, in the case shown in FIG. 5A, a skirt-shaped metal frame 111 is provided around the periphery of the cover member 11. Further, when the cover member 11 is made of an alloy material having conductivity, that is, in the case shown in FIG. 5B, an insulating layer 112 is provided at the contact portion between the cover member 11 and the semiconductor element 4. By providing the insulator as described above, this cap is formed to have a structure that prevents leakage current from the semiconductor element 4. In each figure, a metallized layer 2 is formed at each joint, and a heat sink 6 is provided on the cover member 11 to improve heat dissipation.

[Problems to be Solved by the Invention] However, although alumina has excellent electrical insulation and mechanical strength, its thermal conductivity is as low as 17 Wm-', resulting in poor heat dissipation. It is unsuitable for mounting large amounts of field effect transistors (FETs) and the like. Insulating substrates using beryllia (B e O), which has a high thermal conductivity of 260 Wm-'K-', exist in order to mount semiconductor elements that generate a high amount of heat, but beryllia is toxic and is not safe for use. The problem is that the countermeasures are complicated.

Recently, the thermal conductivity is almost the same as that of beryllia, and 200%
Aluminum nitride (AQN), which has a high Wm-'K-', is non-toxic, and has electrical insulation properties and mechanical strength equivalent to alumina, is viewed as promising.

However, when metal brazing a lead frame to an aluminum nitride substrate, for example, silver brazing (Ag-Cu), aluminum nitride has an average coefficient of thermal expansion of 4.3X10- from room temperature to silver brazing temperature (780°C). Although it is small at 6-', the lead frame is made of iron.
The average coefficient of thermal expansion of nickel-based alloys is 10XIO-'
(Kovar), llXl0-6 to 1' (427
0b), which is extremely high. Therefore, due to this difference in coefficient of thermal expansion, distortion due to large thermal stress as residual stress occurs in the aluminum nitride substrate during the cooling process during silver brazing of the lead frame to the aluminum nitride substrate.

Therefore, when the lead frame is pulled in the direction of peeling it off from the substrate, it easily breaks, resulting in a problem in that sufficient lead frame bonding strength cannot be obtained.

Furthermore, as the amount of heat generated by semiconductor elements increases, there is an urgent need to develop caps with excellent heat dissipation properties.

For example, even if a cap made of a highly thermally conductive metal material is used, it is necessary to provide an insulating portion as described above, which not only increases cost but also causes problems in thermal conductivity.

Therefore, caps made of materials with high thermal conductivity and excellent insulation properties are attracting attention. Candidate materials include beryllia (Bell), silicon carbide (S
i C), aluminum nitride (AfLN) may be considered. However, beryllia and silicon carbide have problems in terms of toxicity, unstable supply, and electrical properties. Therefore, aluminum nitride is the most promising material, but in order to manufacture a cap using aluminum nitride as a cover member, metallization treatment must be performed on the surface of the cover member made of aluminum nitride at the location where it is to be joined to the frame member. After that, it is necessary to solder the cover member and the frame member by metal brazing.

However, metal brazing, such as silver brazing (Ag
-Cu), as mentioned above, the average coefficient of thermal expansion of aluminum nitride from room temperature to the silver brazing temperature (780°C) is as small as -1 to 4.3 x 10-6.
The average coefficient of thermal expansion of low thermal expansion iron-nickel alloys commonly used as frame members is 10XIO-'.
(Kovar) to 11X10-6 (42 alloy), which is extremely high. Therefore, residual strain due to large thermal stress is generated within the cover member made of aluminum nitride. The residual strain causes cracks in the cover member made of aluminum nitride, causing warping and deformation of the frame member, which poses a problem in that it is impossible to provide a cap with high dimensional accuracy, airtightness, and reliability.

Further, in semiconductor packages that require high thermal conductivity, a Cu-W alloy plate is used as a heat dissipation substrate, and beryllia (Bed) is used as a highly heat dissipation insulating substrate. However, when using an insulating substrate made of aluminum nitride instead of beryllia, cracks may occur in the aluminum nitride substrate when connecting the metallized aluminum nitride substrate to a copper-tungsten alloy plate by silver brazing. A new problem has arisen in which copper-tungsten alloy plates warp or warp.

Attempts have been made to seal the sealing cap made of alumina and the aluminum nitride substrate by brazing, but even in this case, cracks and warpage occur in the ceramic member made of alumina and aluminum nitride. It was difficult to seal.

Further, attempts have been made to braze copper plates on both sides of an aluminum nitride substrate using active metal solder at a temperature of about 900° C. as a heat dissipation substrate for high power semiconductor modules. However, even in this case, cracks were observed in the aluminum nitride in some of the samples after being brazed. Samples with no cracks were also heated at -55°C to +150°C for 5 minutes each.
When we conducted a heat cycle test, the number of cycles was 1.
In less than 00 cycles, cracks were observed in the aluminum nitride and peeling of the copper plate was observed.

To summarize the above problems, the heat cycle of the ceramic member made of aluminum nitride and the member made of a material different from aluminum nitride, such as a metal material or other ceramic material, or the connected member. Cracks, cracks, peeling, warping, etc. occur during reliability evaluations such as tests. For example, when silver brazing is applied, as mentioned above, aluminum nitride has a relatively small average coefficient of thermal expansion from room temperature to the silver brazing temperature (about 780°C), whereas Kovar etc. have a low thermal expansion coefficient. The average coefficient of thermal expansion of metals is extremely high.

On the other hand, the coefficient of thermal expansion of materials that are difficult to deform plastically, such as copper-tungsten alloy and alumina, is 6.5 to 9X10-1, and their Young's modulus is 29,000 to 37,000 kg/m.
It is large at m2. Therefore, when aluminum nitride and these dissimilar materials are brazed, extremely large thermal stress will occur during the cooling process of the solder. Therefore, this thermal stress causes cracks to occur during brazing, or exists as residual stress within the joint, which is thought to result in poor reliability in reliability evaluations such as heat cycle tests.

Therefore, the present invention uses a member made of aluminum nitride with good heat dissipation properties in order to mount a semiconductor element with a high calorific value, and a connecting member can be bonded to this member with sufficient bonding strength. It is an object of the present invention to provide a connection structure between parts for a semiconductor device that does not cause cracks or fractures when bonded to different materials, has little deformation, and has extremely high reliability.

[Means for Solving the Problems] According to one aspect of the present invention, a connection structure between parts for a semiconductor device includes a base material made of aluminum nitride and having a main surface on which a semiconductor element is to be placed; It is to be joined to this base material and includes a connecting member whose main material is a material different from aluminum nitride, a cushioning material, and a brazing material for joining the base material, the cushioning material, and the connecting member. .

The buffer material is interposed between the base material and the connecting member, and has a plastic deformability so as to relieve the thermal stress generated due to the difference in thermal expansion coefficient between the base material and the connecting member during the cooling process of soldering. It has a three-layer structure consisting of a soft metal layer made of a highly soft metal material, and a metal layer containing at least one of molybdenum and tungsten sandwiched between the soft metal layers.

Preferably, the soft metal material may be any material selected from the group consisting of copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, iron, and iron alloy. Further, the connecting member is preferably made of an iron-nickel-cobalt alloy or a copper-tungsten alloy.

According to another aspect of the present invention, a cap for airtightly sealing a semiconductor element mounted on an insulating substrate is provided as a connection structure between components for a semiconductor device.

The cap is provided above the semiconductor element to protect it, and includes a cover member made of aluminum nitride;
It should be joined to the cover part so as to surround the semiconductor element located below the cover member, and includes a frame member whose main material is a material different from aluminum nitride, a cushioning material, a cover member and the cushioning material. and a brazing material for joining the frame member. The cushioning material is interposed between the cover member and the frame member, and has a plastic deformability so as to relieve the thermal stress generated due to the difference in thermal expansion coefficient between the cover member and the frame member during the cooling process of wax entertainment. It consists of a soft metal layer made of a highly soft metal material, and a metal layer containing at least one of molybdenum and tungsten sandwiched between the soft metal layers.

[Operation] One possible method for reducing the thermal stress generated during brazing is to insert a cushioning material as an insert between a member made of aluminum nitride and a member made of a different material. This cushioning material is roughly classified into two types. One is a buffer material made of a soft metal material such as copper or nickel that has extremely excellent plastic deformability, and the other is a metal material that has a coefficient of thermal expansion almost equal to that of aluminum nitride and is difficult to plastically deform, such as: Cushioning materials made of metal materials containing molybdenum or tungsten have been proposed.

In other words, these joining methods are: (i) a method in which a soft metal material absorbs the thermal stress generated between dissimilar aluminum nitride materials through plastic deformation, and (11) a method in which molybdenum or tungsten, which has approximately the same coefficient of thermal expansion as aluminum nitride, is used. By interposing a metal material containing aluminum nitride as an insert material, thermal stress is generated between the different materials and the insert material, but since the coefficients of thermal expansion are almost the same between the insert material and aluminum nitride, the generated thermal stress This is a method to prevent aluminum nitride from reaching the same level as aluminum nitride.

However, the former method of inserting a cushioning material made of a soft metal material may not be able to sufficiently absorb the generated thermal stress. If the insert material is thin, its plastic deformability is poor, and if it is too thick,
Although it has high plastic deformability, the thermal stress of the insert itself cannot be ignored, which adversely affects the aluminum nitride member.

Therefore, although there is an optimal thickness, it is difficult to construct an insert material that can sufficiently absorb thermal stress only from soft metal materials.

Further, even in a joining method using a rigid insert material such as molybdenum or tungsten, if the difference in coefficient of thermal expansion between different materials and the insert material is large, the insert material itself may be elastically deformed.

Furthermore, molybdenum or tungsten has a very large Young's modulus, so even if the amount of deformation is small, the stress generated is large. This causes cracks to occur in the aluminum nitride member. Such problems can be solved by increasing the thickness of the insert material made of molybdenum, tungsten, or the like. However, it is difficult to increase the thickness of the insert material due to dimensional constraints in the design of semiconductor devices.

Therefore, through intensive research, the inventors of the present application interposed an insert material made only of a soft metal material or a plastically deformed female metal material such as molybdenum between an aluminum nitride member and a member made of a different material. than if
The thickness of the insert material is small, and the thermal stress relaxation effect brought about by the insert material is large, so that it is possible to provide a highly reliable connection structure that is less deformed and warped, and is free from cracks. That is, the cross-sectional structure of the connection portion is composed of aluminum nitride/soft metal layer/metal layer containing at least one of molybdenum and tungsten/soft metal layer/different material. In this case, the material inserted as a cushioning material may be constructed by brazing each veneer, or may be interposed as a cladding material, that is, an integrated insert hole.

Further, the soldering material for joining the members may be made of any material such as silver solder, gold solder, solder, etc., and is not limited.

For example, when a base material made of an aluminum nitride sintered body and a metal frame such as a connecting member made of Kovar are soldered with silver-copper solder, a soft metal layer/a metal layer containing molybdenum or tungsten/a soft metal layer A cladding material consisting of copper/molybdenum/copper can be selected as a buffer material for nailing. The cross-sectional structure of the partial structure in this case is composed of aluminum nitride/copper/molybdenum/copper/Kovar. Thermal stress caused by the difference in thermal expansion coefficients between Kovar and Molybdenum is reduced by plastic deformation of the copper layer interposed therebetween. Also,
Molybdenum has a Young's modulus of 330001c g/mm.
2 and is difficult to plastically deform, it is thought that the thermal stress generated between the molybdenum layer and Kovar concentrates on the molybdenum layer and is difficult to affect the aluminum nitride. however,
If the thermal stress causes some elastic deformation of the molybdenum, there is a possibility that the thermal stress will be applied to the aluminum nitride due to the strain. Therefore, in order to reduce this thermal stress, a copper layer with high plastic deformability is also interposed between aluminum nitride and molybdenum. by this,
It becomes possible to make aluminum nitride hardly affected by thermal strain. In this way, a bonding structure between the aluminum nitride member and the abrasive material with less thermal strain during brazing can be obtained. Also, reliability tests, e.g. 55
In a heat cycle test from .degree. C. to +150.degree. C., thermal strain caused by this temperature cycle can be alleviated by plastic deformation of the copper.

In this case, since the copper layer is fixed with aluminum nitride or molybdenum, thermal expansion of the copper is also suppressed, and reliability in heat cycles is significantly improved.

As described above, in the connection structure between parts for a semiconductor device according to the present invention, the soft metal layer constituting the buffer material reduces thermal stress during soldering and heat cycles due to its plastic deformation. Further, the metal layer containing at least one of molybdenum and tungsten, which constitutes the buffer material, works to prevent thermal stress from being exerted on the aluminum nitride member due to the different material.

Further, in the connection 114 structure according to the present invention, it is possible to reduce the thickness of the cushioning material used. For example, in brazing an aluminum nitride member and a metal frame made of Kovar, the thickness of the cushioning material that satisfies tests for reliability, warping, cracking, etc. is 0.5 mm with only 81 layers.
, the molybdenum layer alone is 0.4 mm. According to this invention, when the cushioning material is composed of a three-layer structure of copper/molybdenum/copper, the thickness of each layer is 0.0510.110.05 mm.
The total thickness of the cushioning material is 0.2 mm. Therefore, the present invention can be applied even when severe constraints are imposed on the design of a semiconductor device.

[Embodiment] An embodiment of a connection structure between parts for a semiconductor device according to one aspect of the present invention, for example, a connection 1 between a lead frame, a buffer material, and an aluminum nitride substrate will be described with reference to the drawings.

FIG. 1A is a plan view showing an embodiment used as a substrate for mounting a semiconductor device, FIG. 1B is a sectional view thereof, and FIG. 1C is a detailed view of the joint between the lead frame 3 and the substrate 1 made of aluminum nitride. FIG.

In the figure, in this connection structure, a metallized layer 2 is formed on a part of the surface of a substrate 1 made of aluminum nitride as a sintered body, and a lead frame 3 is attached to this metallized layer 2 with metal solder or the like. attached and joined. A buffer material 13 having a nickel plating layer formed on its surface is interposed between the metallized layer 2 and the lead frame 3. This buffer material has a three-layer structure consisting of a soft metal layer such as copper, and a metal layer containing molybdenum or tungsten sandwiched between the soft metal layers. In addition, aluminum nitride substrate 1
A semiconductor element 4 such as a FET that generates a large amount of heat is mounted at a predetermined position, and is connected to the metallized layer 2 or the lead frame 3 with a bonding wire 5.

Furthermore, a heat sink 6 made of a tungsten alloy, such as a copper-tungsten alloy, is attached to the back surface of the aluminum nitride substrate 1. In the bonding between the heat sink 6 and the aluminum nitride substrate 1 as well, the buffer material according to the present invention is interposed as in the case between the aluminum nitride substrate 1 and the lead frame 3.

Further, as shown in FIG. 1C, an aluminum nitride substrate 1
A thin plating layer 7 is formed on the metallized layer 2 at the joint between the lead frame 3 and the lead frame 3. In order to stabilize the wettability of the metal solder 9, the lead frame 3 is coated with a metal such as Kovar as necessary. The plating layer 8 is formed on the outer peripheral surface of the layer 23.

Further, the structure of a cap to which the connection structure between parts for a semiconductor device according to the present invention is applied will be explained with reference to the drawings.

FIG. 2 is a sectional view showing one example. A metallized layer 2 is formed on the peripheral side surface of the cover member 11 made of a sintered aluminum nitride body. A metal layer 230 of an iron-nickel alloy is applied to the metallized layer 2 by a metal solder 9 via a buffer material 130 having a three-layer structure of a soft metal layer such as copper and a metal layer containing molybdenum or tungsten. A frame member 30 made of only one piece is joined. The lower end of the frame member 30 is joined to the ceramic substrate 101 via the metallized layer 2. A semiconductor element 4 is mounted on the ceramic substrate 101. Furthermore, by attaching the heat sink 6 to the upper surface of the cover member 11, the heat generated in the semiconductor element 4 is dissipated by the heat sink 6 through the cover member 11, thereby enhancing its cooling effect.

Although silver solder is preferable as the metal solder 9 used, it is also possible to However, other brazing materials may be used as long as they can be firmly joined together. The role played by this plating layer is as explained in the above-mentioned embodiment of the connection structure between the lead frame and the aluminum nitride substrate.

Example 1 A metallizing treatment was performed on an aluminum nitride sintered substrate as each sample. The size of the aluminum nitride sintered substrate was 20 mm x 1.5 mm. The surface of the metallized layer formed by metallizing treatment has a film thickness of 2 μm.
2: A plating layer was formed. Then, an aluminum nitride sintered substrate with a mouth of 20 mm x 1. Copper with a size of Omm -
The tungsten alloy plate was brazed with silver-copper as a brazing material in a hydrogen atmosphere at a temperature of 830°C.

The thickness of each metal layer constituting the buffer is shown in Table 1.

Each bonded member thus obtained was subjected to a heat cycle test (-55 to +150°C, 100 cycles) using a stereomicroscope and a scanning electron microscope.
The presence or absence of cracks in the cross section of the joint structure was investigated.

The results are shown in Table 1. In addition, in Table 1, O
indicates that no cracks were observed, and x indicates that cracks occurred. Also, sample No.
.

5 to 8 show comparative examples.

According to Table 1, no cracks were observed when the aluminum nitride sintered substrate and the copper-tungsten alloy plate were bonded using the buffer material having the structure according to the present invention. Especially after the heat cycle test,
No cracks were observed in the bonded member according to the present invention.

Example 2 Each sample was prepared in the same manner as in Example 1, and brazed in a hydrogen-nitrogen atmosphere at a temperature of 550° C. using aluminum-silicon as a low-melting point brazing material. The composition and thickness of the buffer material used in each sample are shown in Table 2.

In the same manner as in Example 1, the joint members of each of the obtained samples were examined for the occurrence of cracks. The results are shown in Table 2. Sample No. 3.4 shows a comparative example. According to Table 2, when a sintered aluminum nitride substrate and a copper-tungsten alloy plate are bonded using a buffer material having a structure according to the present invention, no cracks are observed before or after the heat cycle test. It is understood that there is no.

(The following is a blank space) Example 3 FIG. 3 shows a side cross section of each sample prepared as a cap in which a cover member 11 and a frame member 30 were joined. Referring to FIG. 3, tungsten metallization treatment was performed on the outer peripheral side surface of a circular cover member 11 made of aluminum nitride and having a thickness of 1 mm. The outer peripheral side surface of the cover member 11 on which the metallized layer 2 was formed was further subjected to nickel plating treatment. After that, various cushioning materials 1 shown in Table 3
The frame member 30 consisting of only the Kovar metal layer 230 and the cover member 11 were silver-soldered to each other in a hydrogen atmosphere at a temperature of 850° C. with the Kovar metal layer 230 interposed therebetween. The inner diameter of the frame member 30 of each sample thus obtained was 20 mmφ, and the wall thickness was 0.2 mm.

For each sample thus obtained, a reliability evaluation test was conducted in the same manner as in Example 1. The results are shown in Table 3. Further, in order to evaluate the airtightness of each sample as a cap, an airtightness evaluation test was conducted using the He leak check method. The results are also shown in Table 3. In Table 3, ◯ indicates that no cracks were generated or that the airtightness was good, and × indicates that there were cracks or that the airtightness was poor. Sample No.

5.6.7 shows a comparative example.

According to Table 3, when the cushioning material having the structure according to the present invention was used, no cracks were observed and a cap with good airtightness could be obtained.

(Left below) Example 4 Tungsten metallization treatment was applied to both sides of a sintered aluminum nitride substrate. Nickel plating was further applied to the metallized surface. Each sample of the aluminum nitride sintered substrate treated in this way was coated with either a metal plate having the configuration shown in Table 4 or
Brazing was performed in a hydrogen atmosphere at a temperature of 920° C. using silver-copper as a soldering material. In this way, a high power semiconductor module substrate was manufactured.

A heat cycle test was conducted on each of the obtained substrates in the same manner as in Example 1 to check for the occurrence of cracks. The results are shown in Table 4. Sample No. 3 shows a comparative example.

According to Table 4, when a metal plate having the structure according to the present invention is bonded to an aluminum nitride sintered substrate, a high power semiconductor module substrate is produced in which no cracks are observed before or after the heat cycle test. I was able to do that.

[Effects of the Invention] As described above, according to the present invention, when joining an aluminum nitride member and a member made of different materials, a soft metal layer and a metal containing molybdenum or tungsten sandwiched by the soft metal layer are used. By interposing a buffer material having a three-layer structure consisting of the following layers, it is possible to provide a highly reliable connection structure between components for a semiconductor device.

[Brief explanation of the drawing]

1A, 1B, and 1C are plan views showing an embodiment of a connection structure between parts for a semiconductor device according to the present invention, for example, a connection structure between a lead frame, a buffer material, an aluminum nitride IJ, and a plate. FIG. 2 is a cross-sectional view. FIG. 2 is a sectional view showing an embodiment of the present invention applied to a cap as a connection structure between parts for a semiconductor device. FIG. 3 is a side sectional view showing each sample as a cap prepared in Example 3. FIGS. 4A, 4B, and 4C are a plan view and a sectional view showing a conventional connection structure between components for a semiconductor device, for example, a connection structure between a lead frame and an alumina substrate. 5A and 5B are cross-sectional views showing a conventional connection structure between components for a semiconductor device, for example, a connection structure used in a cap for hermetically sealing a semiconductor element mounted on an insulating substrate. In the figure, 1 is a board, 3 is a lead frame, 6 is a heat sink, 9 is a metal solder, 11 is a cover member, 13, 1
30 is a cushioning material, and 30 is a frame member. In each figure, the same number 7 indicates the same or equivalent part. Figure 1A Figure 2 Figure 78 Figure 130: 慴iη1THIO↑ Figure 1C Figure 3 Figure 13: Loose T Acupuncture Figure 4A Figure 4B Figure 4 Evening A Figure Figure 5B

Claims (5)

[Claims] (1) A base material made of aluminum nitride and having a main surface on which a semiconductor element is to be placed, and a connecting member that is to be joined to the base material and whose main material is a material different from the aluminum nitride. , a buffer material interposed between the base material and the connection member, and a brazing material for joining the base material, the buffer material, and the connection member, the buffer material being used for cooling during brazing. In the process, a soft metal layer made of a soft metal material with high plastic deformability is sandwiched between the soft metal layers so as to alleviate the thermal stress generated due to the difference in thermal expansion coefficient between the base material and the connection member. A connection structure between parts for a semiconductor device, the structure having a three-layer structure including a metal layer containing at least one of molybdenum and tungsten. (2) The semiconductor device according to claim 1, wherein the soft metal material is made of any material selected from the group consisting of copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, iron, and iron alloy. Connection structure between parts. (3) The connection structure between parts for a semiconductor device according to claim 1, wherein the connection member is made of an iron-nickel-cobalt alloy. (4) The connection structure between parts for a semiconductor device according to claim 1, wherein the connection member is made of a copper-tungsten alloy. (5) A connection structure between parts for a semiconductor device for hermetically sealing a semiconductor element mounted on an insulating substrate, the structure being provided above the semiconductor element to protect it;
A cover member made of aluminum nitride, and a frame member that is to be joined to the cover member so as to surround the semiconductor element located below the cover member, and whose main material is a material different from the aluminum nitride. and a buffer material interposed between the cover member and the frame member, and a brazing material for joining the cover member, the buffer material, and the frame member, the buffer material being used during soldering. In the cooling process, a soft metal layer made of a soft metal material with high plastic deformability is sandwiched between the soft metal layers so as to relieve thermal stress caused by a difference in thermal expansion coefficient between the cover member and the frame member. A connection structure between parts for a semiconductor device, the structure having a three-layer structure including a metal layer containing at least one of molybdenum and tungsten.