JP2525873B2 - Connection structure between semiconductor device parts - Google Patents

Description

The present invention relates to a connection structure between semiconductor device parts,
In particular, the present invention relates to a connection structure between semiconductor device parts that require high thermal conductivity for mounting a semiconductor element having a high heating value, such as a high power transistor and a laser diode.

[Related Art] A connection structure between components for a semiconductor device configured to mount a semiconductor element generally includes an insulating base material and a bonding member bonded thereto. For example,
The connection structure is an insulating substrate on which a semiconductor element is mounted, a lead frame connected to a predetermined portion of the insulating substrate on which a wiring circuit and the like are formed by brazing using silver solder, or the like. The heat sink is connected to the insulating substrate by brazing using silver solder or the like. In this case, the insulating substrate is generally required to have high electrical insulation, high mechanical strength, and high thermal conductivity to dissipate heat generated from the semiconductor element in order to maintain insulation from the semiconductor element. Further, the lead frame is required to have a low electric resistance and a high mechanical strength. Further, the heat sink is required to have high thermal conductivity.

As a material for such a connection structure between semiconductor device parts, for example, an insulating substrate used for a semiconductor device package, an electronic part, etc., alumina (Al
₂ O ₃ ) is generally selected to satisfy the above properties. The following are examples of various metallic materials to be connected to the insulating substrate. For example, as lead frames, iron-nickel-based materials such as Kovar (Fe-29 wt% Ni-17 wt% Co alloy) and 42 alloy (Fe-42 wt% Ni alloy) that satisfy the above characteristics Alloys are generally selected. As the heat sink, a copper-tungsten alloy (W-10 to 20 wt% Cu alloy) is generally selected so as to satisfy the above characteristics. "Chemical Industry" March 1984, Special Issue on Electroceramics, "Ceramic Substrates and IC Packages" p.
59-67, in the portion of the metallization layer formed as a wiring circuit on an insulating substrate made of alumina,
A connection structure in which a lead frame made of the product name Kovar is brazed with silver solder or the like is used for a semiconductor device mounting substrate.

FIG. 4A is a plan view showing an example of a conventional connecting structure for semiconductor device parts having the above-mentioned structure, FIG. 4B is a sectional view thereof, and FIG. 4C is a lead frame 3 and a substrate 1 made of alumina. It is sectional drawing which shows the junction part of in detail.

In the figure, the connection structure between the semiconductor device parts is
A metallized layer 2 is formed on a part of the surface of a substrate 1 made of alumina, and a lead frame 3 is brazed and joined to the metallized layer 2 with a brazing metal or the like. A semiconductor element 4 such as a field effect transistor (FET) having a high heat generation amount is mounted at a predetermined position on the substrate 1, and is connected to the metallized layer 2 or the lead frame 3 with a bonding wire 5. Furthermore, on the back surface of the substrate 1, a tungsten alloy,
For example, a heat sink 6 made of a copper-tungsten alloy is attached. Further, as shown in FIG. 4C, a thin plating layer 7 is formed on the metallization layer 2 at the joint between the substrate 1 and the lead frame 3, and the wettability of the metal braze 9 on the surface of the lead frame 3. A plating layer 8 is formed as necessary to stabilize the temperature.

Another example of a connection structure between components for a semiconductor device is a cap for hermetically sealing a semiconductor element mounted on an insulating substrate. The material of the cap for semiconductor device encapsulation that requires high reliability is 42
Low thermal expansion alloy materials such as alloy and Kovar, or ceramics materials such as alumina and mullite are used.

Its structure is as shown in FIGS. 5A and 5B. That is, in the drawing, the semiconductor element 4 is mounted on a ceramic substrate 101, and a cover member 11 is put on the ceramic substrate 101. 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 on the peripheral edge of the cover member 11. Further, when the cover member 11 is an alloy material having conductivity, that is, in the case shown in FIG. 5B,
An insulating layer is provided on the contact portion between the cover member 11 and the semiconductor element 4.
112 are provided. By providing the insulator as described above, the cap is formed so as to have a structure for preventing a leak current of the semiconductor element 4. In each of the drawings, a metallized layer 2 is formed at each joint, and a heat sink 6 is provided on the cover member 11 to enhance heat dissipation.

[Problems to be Solved by the Invention] However, while alumina has excellent electric insulation and mechanical strength, it has a low thermal conductivity of 17 Wm ^-1 K ^-1 and thus has a poor heat dissipation property. It is not suitable for mounting a large amount of field effect transistor (FET). There is an insulating substrate that uses beryllia (BeO), which has a high thermal conductivity of 260 Wm ^-1 K ^-1 to mount a semiconductor element with high heat generation, but beryllia is toxic and complicated safety measures are required during use. There is a problem that is.

Therefore, recently, as an insulating substrate for mounting a semiconductor element with a high calorific value, thermal conductivity is almost the same as that of beryllia, 200 W
It is as high as m ^-1 K ^-1 , has no toxicity, and has the same electrical insulation and mechanical strength as alumina.
N) is promising.

However, the metal brazing the lead frame to an aluminum nitride substrate, for example, to marked silver solder (Ag-Cu), the average thermal expansion coefficient of aluminum nitride is from room temperature to the silver brazing temperature (780 ° C.) is 4.3 × 10 ^- whereas low as ⁶ K ^-1, iron is a lead frame - nickel average thermal expansion coefficient 10 × 10 ^-6 K alloy ^-1 (Kovar), 11 × 10 ^-6 K
^-1 (42 alloy), extremely high. Therefore, due to the difference in the coefficient of thermal expansion, distortion due to a large thermal stress is generated as a residual stress in the aluminum nitride substrate during the cooling process during the silver brazing of the lead frame to the aluminum nitride substrate. Therefore, when the lead frame is pulled in the direction of peeling it from the substrate, the lead frame is easily broken and there is a problem that sufficient lead frame bonding strength cannot be obtained.

Further, with the increase in the heat generation amount of the semiconductor element, development of a cap excellent in heat dissipation is urgently required. For example, even if a cap made of a metal material having high thermal conductivity is used, it is necessary to provide an insulating portion as described above, which not only increases cost but also causes a problem in thermal conductivity.

Therefore, a cap made of a material having a high thermal conductivity and an excellent insulating property is drawing attention. Beryllia (BeO), silicon carbide (SiC), and aluminum nitride (AlN) can be considered as the candidate materials. However, beryllia and silicon carbide have problems in terms of toxicity, unstable supply and electrical characteristics. Therefore, although aluminum nitride is most effective, in order to manufacture a cap using aluminum nitride as a cover member, metallization is applied to the surface of the cover member made of aluminum nitride at the portion to be joined with the frame member. After that, it is necessary to braze the cover member and the frame member by metal brazing.

However, metal brazing, for example silver brazing (Ag
-Cu), the average coefficient of thermal expansion of aluminum nitride from room temperature to the temperature during silver brazing (780 ° C) is as small as 4.3 x 10 ^-6 K ^-1 as described above, whereas it is used as a frame member. The average coefficient of thermal expansion of commonly used low thermal expansion iron-nickel alloys is 10 × 10 ^-6 K ^-1 (Kovar) to 11 × 10 ^-6 K.
^-1 (42 alloy), extremely high. As a result, residual strain due to large thermal stress is generated in the cover member made of aluminum. The residual strain causes a crack in the cover member made of aluminum nitride, and the frame member is warped or deformed, so that there is a problem that it is not possible to provide a cap with high dimensional accuracy, airtightness, and reliability. .

Furthermore, a Cu-W alloy plate as a heat dissipation substrate and beryllia (BeO) as a high heat dissipation insulating substrate are used in a semiconductor package that requires high heat conductivity. However, when using an insulating substrate made of aluminum nitride in place of beryllia and connecting the metallized aluminum nitride substrate to the copper-tungsten alloy plate by silver brazing, the aluminum nitride substrate is cracked. There has been a new problem that a copper-tungsten alloy plate is warped.

Attempts have been made to seal the cap made of alumina and the aluminum nitride substrate by brazing, but in this case as well, cracks or warpage occur in the ceramic member made of alumina or aluminum nitride. Therefore, it was difficult to perform the sealing.

Further, as a heat dissipation substrate for a high power semiconductor module, brazing has been attempted by using an active metal braze at a temperature of about 900 ° C. for copper plates on both sides of an aluminum nitride substrate. However, even in this case, cracks were observed in the aluminum nitride in a part of the sample after brazing. The samples with no cracks were also subjected to a heat cycle test at -55 ° C to + 150 ° C for 5 minutes each.
Within less than the number of times, cracking of the aluminum nitride and peeling of the copper plate were observed.

To summarize the above problems, when a ceramic member made of aluminum nitride is brazed with a material made of a metal material or another ceramic material and made of a material different from aluminum nitride, or the heat cycle of the connected members. In reliability evaluations such as tests, cracks, breaks, peeling, warpage, etc. occur. For example, when silver brazing is applied, as described above, aluminum nitride has a relatively low average thermal expansion coefficient from room temperature to the silver brazing temperature (about 780 ° C), while low thermal expansion coefficient such as Kovar. The average coefficient of thermal expansion of the metal is extremely high. On the other hand, the coefficient of thermal expansion of materials such as copper-tungsten alloy and alumina which are not easily plastically deformed is 6.5 to 9 × 10 ^-6 K ^-1 , and their Young's modulus is 2000 to
Large as 37,000 kg / mm ² . Therefore, when aluminum nitride and these dissimilar materials are brazed, an extremely large thermal stress is generated in the cooling process during the brazing. Therefore, it is considered that this thermal stress causes a crack to occur during brazing or exists as a residual stress in the member, so that the reliability becomes poor in reliability evaluation such as a heat cycle test.

Therefore, the present invention uses a member made of aluminum nitride having a good heat dissipation property for mounting a semiconductor element having a high heat generation amount, and a connecting member can be bonded to this member with sufficient bonding strength, and at the same time, aluminum nitride can be bonded. An object of the present invention is to provide a highly reliable connection structure between semiconductor device parts that does not cause cracks or cracks in joining with a material different from the above, has little deformation, and is highly reliable.

[Means for Solving the Problems] According to one aspect of the present invention, a connection structure between semiconductor device parts has a base material made of aluminum nitride having a main surface on which a semiconductor element is to be mounted, It should be joined to this base material, and is provided with a connection member mainly made of a different material from aluminum nitride, a cushioning material, and a brazing material for joining the base material, the cushioning material and the connection member.
The cushioning material is interposed between the base material and the connecting member, and has a plastic deformability so as to relieve the thermal stress generated by the difference in the coefficient of thermal expansion between the base material and the connecting member during the cooling process during brazing. And a soft metal layer made of a soft metal material having a high temperature, and a metal layer containing at least one metal of molybdenum and tungsten sandwiched by the soft metal layer.

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. The connecting member is preferably made of iron-nickel-cobalt alloy or copper-tungsten alloy.

According to another aspect of the present invention, a cap for hermetically sealing a semiconductor element mounted on an insulating substrate is provided as a connection structure between semiconductor device parts. This cap is provided above the semiconductor element so as to protect the semiconductor element, and should be joined to the cover member so as to surround the cover member made of aluminum nitride and the semiconductor element located below the cover member. A frame member mainly made of a material different from aluminum nitride, a cushioning material, and a brazing material for joining the cover member, the cushioning material and 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 the coefficient of thermal expansion between the cover member and the frame member during the cooling process during brazing. And a soft metal layer made of a soft metal material, and a metal layer containing at least one metal of molybdenum and tungsten sandwiched by the soft metal layer.

[Operation] As one method for reducing the thermal stress generated during brazing, it is conceivable to insert a cushioning material as an insert material 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 of them is a cushioning material made of a soft metal material such as copper or nickel having an excellent plastic deformability, the other is a metal material having a thermal expansion coefficient almost equal to that of aluminum nitride and hard to plastically deform, for example, A cushioning material made of a metal material containing molybdenum or tungsten has been proposed.

That is, the joining methods are (i) a method of absorbing the thermal stress generated between the dissimilar material and aluminum nitride by plastically deforming the soft metal material, (ii) molybdenum having a thermal expansion coefficient almost equal to that of aluminum nitride, or By interposing a metal material containing tungsten or the like as an insert material, thermal stress is generated between the dissimilar material and the insert material, but since the thermal expansion coefficients are almost equal between the insert material and aluminum nitride, the generated heat This is a method to prevent stress from reaching aluminum nitride.

However, the thermal stress generated may not be sufficiently absorbed only by the former method of inserting the cushioning material made of a soft metal material. If the thickness of the insert material is thin, its plastic deformability is poor, and if it is too thick, its plastic deformability is rich, but the thermal stress of the insert material itself cannot be ignored, and it adversely affects the aluminum nitride member. Therefore, although there is an optimum thickness, it is difficult to form the insert material that can sufficiently absorb the thermal stress from only the soft metal material.

Even in a joining method using a rigid insert material such as molybdenum or tungsten, if the difference in the coefficient of thermal expansion between the different materials and the insert material is large, the insert material itself may elastically deform. In addition, molybdenum or tungsten has a very high Young's modulus,
Even if the amount of deformation is small, the generated stress is large. This causes cracks and cracks in the aluminum nitride member. Such a problem 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 restrictions on the design dimensions of the semiconductor device.

Therefore, the inventors of the present application have earnestly studied, and compared with the case where an insert material made of only a soft metal material or a metal material such as molybdenum which is not easily plastically deformed is interposed between an aluminum nitride member and a member made of a different material. In addition, it was possible to provide a highly reliable connection structure in which the thickness of the insert material is thin, the effect of thermal stress relaxation provided by the insert material is large, deformation and warpage are small, and cracks do not occur. . That is, the cross-sectional structure of the connection portion is composed of aluminum nitride / soft metal layer / metal layer containing at least one metal of molybdenum and tungsten / soft metal layer / different material. In this case, the material inserted as the cushioning material may be configured by brazing each single plate, or may be interposed as a clad material, that is, an integrated insert material. Also, the brazing material for joining the members is silver braze,
It may be made of any material such as gold solder or solder,
Not limited.

For example, a base material made of an aluminum nitride sintered body,
When brazing with a metal frame as a connecting member made of Kovar with silver-copper brazing, it is composed of copper / molybdenum / copper as a buffer material having a soft metal layer / a metal layer containing molybdenum or tungsten / a soft metal layer. A clad material can be selected. The sectional structure of the partial structure in this case is composed of aluminum nitride / copper / molybdenum / copper / kovar. The thermal stress generated by the difference in the coefficient of thermal expansion between Kovar and molybdenum is reduced by the plastic deformation of the copper layer interposed therebetween. In addition, since the Young's modulus of molybdenum is as large as 33000 kg / mm ² and it is difficult to plastically deform, it is considered that the thermal stress generated between the molybdenum and Kovar concentrates in the molybdenum layer and hardly affects the aluminum nitride. However, if the thermal stress causes some elastic deformation of molybdenum,
Due to the strain, the aluminum nitride has a plasticity in which thermal stress is exerted. Therefore, in order to reduce this thermal stress, a copper layer having high plastic deformability is also interposed between aluminum nitride and molybdenum. This makes it possible to prevent the influence of thermal strain on aluminum nitride. In this way, a joint structure of the aluminum nitride member and the dissimilar material with less thermal strain during brazing can be obtained. Also, reliability test, for example, -55 ℃ ~ +150 ℃
In the heat cycle test, the thermal strain generated by this temperature cycle can be relaxed by the plastic deformation of copper. In this case, since the copper layer is fixed to aluminum nitride or molybdenum, the thermal expansion of copper is suppressed and the reliability in the heat cycle is significantly improved.

As described above, in the connection structure between semiconductor device parts according to the present invention, the soft metal layer forming the cushioning material reduces its thermal stress during brazing and heat cycle due to its plastic deformation. Further, the metal layer containing at least one of the metals of molybdenum and tungsten, which constitutes the buffer material, works so as not to affect the thermal stress with the dissimilar material and the aluminum nitride member.

Further, in the connection 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, reliability, warpage, the thickness of the cushioning material that satisfies the tests such as cracks is 0.5 mm only for the copper layer and 0.4 mm for the molybdenum layer only. is there. According to the present invention, when the cushioning material has a three-layer structure of copper / molybdenum / copper, the thickness of each layer is 0.05 / 0.1 / 0.05 mm and the thickness of the entire cushioning material is 0.2 mm. Therefore, the present invention can be applied even when severe restrictions are imposed on the design of the semiconductor device.

[Embodiment] An embodiment of a connection structure between semiconductor device parts according to one aspect of the present invention, for example, a connection structure of a lead frame, a cushioning 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 semiconductor device mounting substrate, FIG. 1B is a cross-sectional view thereof, and FIG. 1C shows a joint portion between a lead frame 3 and a substrate 1 made of aluminum nitride in detail. It is sectional drawing shown.

In the figure, this connection structure has a metallization layer 2 on a part of the surface of a substrate 1 made of aluminum nitride as a sintered body.
The lead frame 3 is brazed and joined to the metallized layer 2 with a brazing metal or the like. Metallized layer 2
Between the lead frame 3 and the lead frame 3, a cushioning material 13 having a nickel plating layer formed on its surface is interposed. This cushioning material has a three-layer structure including a soft metal layer such as copper and a metal layer containing molybdenum or tungsten sandwiched by the soft metal layer. Also, the aluminum nitride substrate 1
A semiconductor element 4 such as a FET having a high heat generation amount is mounted at a predetermined position of, and is connected to the metallized layer 2 or the lead frame 3 by a bonding wire 5.

Further, a sheet sink 6 made of a tungsten alloy, for example, a copper-tungsten alloy, is attached to the back surface of the aluminum nitride substrate 1. This heat sink 6
Also in the bonding between the aluminum nitride substrate 1 and the aluminum nitride substrate 1, the cushioning material according to the present invention is interposed similarly to between the aluminum nitride substrate 1 and the lead frame 3.

Also, as shown in FIG. 1C, the 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, and the lead frame 3 is made of metal such as Kovar as necessary in order to stabilize the wettability of the metal braze 9. The plating layer 8 is formed on the outer peripheral surface of the layer 23.

The structure of a cap to which a connection structure between components for a semiconductor device according to the present invention is applied will be described with reference to the drawings.

FIG. 2 is a sectional view showing an example thereof. The metallized layer 2 is formed on the peripheral side surface of the cover member 11 made of an aluminum nitride sintered body. The metallized layer 2 is formed of a metal layer 230 of an iron-nickel alloy by a metal braze 9 through 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 composed only of is joined. The lower end of the frame member 30 is joined to the ceramic base material 101 via the metallized layer 2. The 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, heat generated in the semiconductor element 4 is radiated by the heat sink 6 through the cover member 11, and the cooling effect is enhanced. Further, silver braze is preferably used as the metal braze 9, but by forming a thin coating layer of a metal having good wettability with the brazing material on the joint surface of the frame member 30 or on the metallized layer 2, etc. Other brazing materials may be used as long as they can be firmly joined. The role of this plating layer is as described in the embodiment of the connection structure between the lead frame and the aluminum nitride substrate.

Example 1 An aluminum nitride sintered substrate as each sample was subjected to a metalizing treatment. The size of the aluminum nitride sintered substrate was 20 mm × t1.5 mm. A nickel plating layer having a film thickness of 2 μm was formed on the surface of the metallized layer formed by the metallizing treatment. Then, with the buffer material shown in Table 1 interposed, the aluminum nitride sintered substrate and the opening 20 mm
A copper-tungsten alloy plate having a size of × t1.0 mm was brazed in a hydrogen atmosphere at a temperature of 830 ° C. using silver-copper as a brazing material. The thickness of each metal layer constituting the cushioning material is shown in Table 1.

Before and after the heat cycle test (-55 to + 150 ° C, 100 cycles), each of the joint members thus obtained was tested.
The presence or absence of cracks in the cross section of the joint structure was examined using a stereoscopic microscope and a scanning electron microscope. The results are shown in Table 1. In Table 1, ◯ indicates that no crack was found, and x indicates that a crack was created. Test Nos. 5 to 8 show comparative examples.

According to Table 1, when the aluminum nitride sintered substrate and the copper-tungsten alloy plate were joined using the cushioning material having the structure according to the present invention, no cracks were observed. In particular, after the heat cycle test, no crack was found in the joint member according to the present invention.

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

In the joined members of the obtained samples, the presence or absence of cracks was examined in the same manner as in Example 1. The results are shown in Table 2. Sample Nos. 3 and 4 show comparative examples. According to Table 2, when the aluminum nitride sintered substrate and the copper-tungsten alloy plate are joined together using the cushioning material having the structure according to the present invention, cracks are completely observed before and after the heat cycle test. It is understood that there is no.

Example 3 FIG. 3 shows a side cross section of each sample prepared as a cap in which the cover member 11 and the frame member 30 are joined. Referring to FIG. 3, the outer peripheral side surface of a circular cover member 11 made of aluminum nitride and having a thickness of 1 mm was subjected to a tungsten metallizing treatment. Cover member with metallized layer 2 formed
The outer peripheral side surface of 11 was further plated with nickel. After that, the frame member 30 consisting of only the Kovar metal layer 230 and the cover member 11 were silver-brazed in a hydrogen atmosphere at a temperature of 850 ° C. with various buffer materials 130 shown in Table 3 interposed. The frame member 30 of each sample thus obtained had an inner diameter of 20 mmφ and a wall thickness of 0.2 mm.

A reliability evaluation test was conducted on each of the samples thus obtained in the same manner as in Example 1. The results are shown in Table 3. Moreover, in order to evaluate the airtightness of each sample as a cap, the airtightness evaluation test was conducted by the He leak check method. The results are also shown in Table 3. In Table 3, ∘ indicates that no cracks were generated or the airtightness was good, and x indicates that cracks were generated or the airtightness was poor. Sample No. 5,
6 and 7 show comparative examples.

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

Example 4 A tungsten metallizing treatment was applied to both surfaces of an aluminum nitride sintered substrate. The surface subjected to the metallizing treatment was further subjected to nickel plating treatment. For each sample of the aluminum nitride sintered substrate thus treated, a metal plate having the structure shown in Table 4 was used in a hydrogen atmosphere at a temperature of 920 ° C. using silver-copper as a brazing material. Was attached. In this way, a high-power semiconductor module substrate was manufactured.

A heat cycle test was performed on each of the obtained substrates in the same manner as in Example 1 to check whether or not cracks were generated. The results are shown in Table 4. Sample No. 3 shows a comparative example.

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

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

[Brief description of drawings]

1A, 1B, 1C is an embodiment of a connection structure between semiconductor device parts according to the present invention, for example, a plan view showing a joint structure of a lead frame, a buffer material and an aluminum nitride substrate, FIG. FIG. 2 is a sectional view showing an embodiment applied to a cap as a connecting structure between semiconductor device parts according to the present invention. FIG. 3 is a side sectional view showing each sample as a cap prepared in Example 3. FIG. 4A, FIG. 4B, and FIG. 4C are a plan view and a sectional view showing a conventional connection structure between semiconductor device parts, for example, a connection structure between a lead frame and an alumina substrate. 5A and 5B are sectional views showing a conventional connection structure between semiconductor device parts, for example, a connection structure used for a cap for hermetically sealing a semiconductor element mounted on an insulating substrate. In the figure, 1 is a substrate, 3 is a lead frame, 6 is a heat sink, 9 is a brazing metal, 11 is a cover member, 13 and 130 are cushioning materials, and 30 is a frame member. In each drawing, the same reference numerals indicate the same or corresponding parts.

Front page continuation (72) Inventor Akira Yamakawa 1-1-1 Kunyokita, Itami City, Hyogo Prefecture, Sumitomo Electric Industries, Ltd. Itami Works (56) References Japanese Patent Laid-Open No. 103853

Claims (5)

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