JP6720534B2 - Assembly manufacturing method, pressure joining container and pressure joining apparatus - Google Patents

Description

The present invention relates to a method of manufacturing an assembly having a joint portion, a pressure joining container, and a pressure joining device.

Lead solder, which has been conventionally used as a chip bonding material for power devices, may become unusable due to environmental regulations in the future, and the development of alternative materials is urgently needed. As an alternative material, a sintered metal joining material that realizes joining by sintering metal particles of nanometer order or micrometer order is expected.

In order to maintain the bonding strength of the sintered metal bonding material, it is desirable to perform the sintering heat treatment while applying pressure in the bonding direction of the electronic member, as disclosed in Patent Document 1, for example. Patent Document 2 describes a method of maintaining the bonding strength even in the direction orthogonal to the pressing direction.

JP, 2013-091835, A JP, 2014-200825, A

Generally, a motor or a pressurizing mechanism using hydraulic pressure is used as a method for applying a pressing force to the sintered metal joining material. Since the lead solder that has been used conventionally does not require a pressurizing step, it is necessary to add a pressurizing step to the conventional manufacturing line in order to apply the sintered metal joining material, which causes a cost problem. there were.

Patent Document 2 describes a method of applying pressure with a jig using an elevating mechanism and a pressure spring. However, when a jig having such a complicated structure is used in a high temperature environment, a problem occurs due to deterioration of the jig. Although a method of simply mounting a weight is also conceivable, there is a case where a weight of about 200 kg is required for one chip depending on the chip size, which is not realistic. Therefore, it has been desired to realize pressure heating bonding by a simpler method.

An object of the present invention is to realize pressure bonding for forming a bonding portion by sintering a bonding material containing metal fine particles without using a complicated pressing mechanism.

A method of manufacturing an assembly according to the present invention is a method of manufacturing an assembly including a first member and a second member and having a joint between them by pressurization and heating, The first supporting member and the second supporting member are provided between the first supporting member and the second supporting member by sandwiching the bonding material containing the metal fine particles between the first supporting member and the second supporting member. The first support member and the second support, which are arranged so as to be sandwiched so as to maintain a distance from the member, heat the first member, the second member, and the bonding material, and suppress thermal expansion of these at that time. The bonding material is pressed using the compressive stress from the member, whereby the metal fine particles of the bonding material are sintered to form the bonding portion.

According to the present invention, since a compressive stress, which is a reaction that suppresses thermal expansion, can be used without using a complicated pressurizing mechanism, pressurization for forming a joint part by sintering a joining material containing metal fine particles is performed. Bonding can be realized.

Further, according to the present invention, the thickness of the joint portion can be set to a desired value.

It is sectional drawing which shows 1 process of the manufacturing method of the assembly which is the 1st Embodiment of this invention. It is a figure which shows an example of the pressure welding apparatus which is the 1st Embodiment of this invention. It is sectional drawing which shows 1 process of the manufacturing method of the assembly which is the 2nd Embodiment of this invention. It is sectional drawing which shows the pressure joining container which is an example of the structure corresponding to FIG. It is sectional drawing which shows an example of a structure for fixing a semiconductor device in the pressure bonding container of FIG. It is a figure which shows the installation process of the semiconductor device in the modification of the pressure bonding container of FIG. It is sectional drawing which shows 1 process of the manufacturing method of the assembly which is the 3rd Embodiment of this invention. It is a graph which shows the stress strain relation of the buffer member 19 of FIG. 6 is a flowchart showing a method for manufacturing an assembly of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described here, and can be appropriately combined and improved without departing from the technical idea of the invention.

(First embodiment)
FIG. 1 is a cross-sectional view showing one step of a method for manufacturing an assembly according to the first embodiment of the present invention. Here, the case where the assembly is a semiconductor device is shown.

The semiconductor device 10 manufactured using at least the first member 11, the second member 12, and the bonding material 13 is sandwiched between the first supporting member 51 and the second supporting member 52, both of which have high rigidity. The first support member 51 has the first surface 14 and the second support member 52 has the second surface 15. The first surface 14 contacts the first member 11, and the second surface 15 contacts the second member 12. The bonding material 13 contains fine metal particles. In this case, the first support member 51 and the second support member 52 are installed so that the distance between them is maintained.

The first member 11 and the second member 12 may be made of any material. For example, the first member 11 may be a semiconductor chip made of a material such as Si or SiC, or the second member 12. A substrate made of a material such as AlN, Cu, AlN, or Cu can be applied. It should be noted that the surfaces of the first member 11 and the second member 12 may be subjected to various plating treatments such as Ni and Ag. In addition, the number of materials forming the semiconductor device such as sealing resin and wiring may increase. As the bonding material 13, a paste material in which fine metal particles such as silver, copper, silver oxide, and copper oxide are mixed in a dispersion medium, or a sheet material prepared by sintering fine metal particles in advance is applicable. it can.

The first surface 14 and the second surface 15 are fixed in place so as not to be affected by heat. In this figure, they are fixed at positions facing each other in the vertical direction. When the entire semiconductor device 10 is heated in this state, the semiconductor device 10 tries to thermally expand, but since the positions of the first surface 14 and the second surface 15 are fixed, compressive stress is generated in the bonding material 13. .. Although any heating method may be used, for example, there is a method of heating from the second surface 15 on the lower surface with a heater.

FIG. 2 shows more specifically an example of the apparatus configuration corresponding to FIG.

The upper lid 21 corresponding to the first supporting member has the first surface 14 and has the heat insulating material 25 inside. On the other hand, the heater 23 corresponding to the second support member has the second surface 15 and is arranged so as to heat the semiconductor device 10.

The position of the upper lid 21 is fixed by an external lock mechanism 22. The height of the inner surface of the upper lid 21 is adjusted so as to contact the upper surface of the semiconductor device 10. Since the height of the semiconductor device 10 differs depending on the type, it is preferable that the semiconductor device 10 has a function of adjusting the height of the upper lid 21. When copper or copper oxide is used, it is also preferable that the furnace has a function of changing the atmosphere to a reducing atmosphere or an inert atmosphere.

Although the semiconductor device 10 thermally expands due to the heating of the heater 23, the upper lid 21 has a heat insulating structure, and thus is not affected by heat and is not deformed due to thermal expansion. Therefore, the position of the first surface 14, which is the inner surface of the upper lid 21, does not change. Therefore, appropriate compressive stress is applied to the bonding material 13 of the semiconductor device 10, and desired pressure-heat bonding is achieved.

According to the configuration shown in FIG. 2, since the position of the upper lid 21 is fixed and the distance between the first surface 14 and the second surface 15 is maintained at the time of pressurization, the thickness of the joint portion is set to a desired value. can do.

According to the present embodiment, it is possible to realize pressure heating bonding without using a pressure mechanism.

(Second embodiment)
FIG. 3 is a cross-sectional view showing a step of the method of manufacturing the assembly according to the second embodiment of the present invention.

In this figure, the positions of the first surface 14 and the second surface 15 that sandwich the semiconductor device 10 are fixed by the third support member 16. Here, the fixing method is not particularly limited and may be joining by welding, tightening with bolts, or the like. The third support member 16 is composed of a member having a coefficient of thermal expansion lower than an equivalent coefficient of thermal expansion α _{d in} the bonding direction of the semiconductor device 10 (hereinafter, also referred to as “thickness direction” or “pressurizing direction”). There must be. The equivalent thermal expansion coefficient α _d of the semiconductor device 10 can be calculated by the following formula.

Here, α _i is a coefficient of thermal expansion in the bonding direction (thickness direction or pressure direction) of each member constituting the semiconductor device 10, t _i is the thickness of each member, h is the thickness of the entire semiconductor device 10, N is the total number of materials forming the semiconductor device 10.

For example, as the configuration of the semiconductor device 10, the first member 11 has a Si chip (α ₁ =3.2×10 ⁻⁶ /K, t ₁ =0.3 mm), and the second member 12 has Cu (α ₂ =). 17.0×10 ⁻⁶ /K, t ₂ =3.0 mm), when the bonding material 13 is sintered silver (α ₃ =23.7×10 ⁻⁶ /K, t ₃ =0.075 mm), The equivalent linear expansion coefficient α _d is about 15.9×10 ⁻⁶ /K. The third support member 16 needs to be a structural material having a lower coefficient of thermal expansion and higher rigidity than this. Examples of such a structural material include carbon steel (α=10.8×10 ⁻⁶ /K), iron (α=12.1×10 ⁻⁶ /K), SUS410 (α=10.4×10). ^-6 /K) or the like can be applied. Further, as the third support member 16, a material having a negative thermal expansion or a zero thermal expansion material may be applied.

Further, the third support member 16 is preferably made of a material having a higher elastic modulus than the bonding material 13. It should be noted that, in the configuration of the semiconductor device 10 (Si, sintered silver, Cu), when iron is used as the third support member 16 and a uniform temperature change of about 175° C. is applied, it corresponds to the bonding material 13. It has been confirmed by finite element analysis that the compressive stress in the thickness direction generated in the sintered silver layer is about 20 MPa. This is a sufficient pressure for the sintered silver to be sinter-bonded with high strength. As described above, the compressive stress generated in the bonding material 13 can be predicted by the finite element analysis, and the pressure level thereof can be appropriately controlled by the material of the third support member 16 and the peripheral structure. is there.

The third supporting member 16 is heated together with the semiconductor device 10, and a compressive stress is generated in the bonding material 13 of the semiconductor device 10 due to a difference in thermal expansion amount between the third supporting member 16 and the semiconductor device 10 at that time, The first member 11 and the second member 12 are pressure-bonded by the bonding material 13. Although any heating method may be used, for example, there is a method in which a jig (pressure bonding container) surrounding the semiconductor device 10 is placed in a furnace.

FIG. 4 specifically shows a pressure-bonding container which is an example of a configuration corresponding to FIG.

In FIG. 4, the jig 20 (pressurizing and joining container) includes a first support member 17 having a first surface, a second support member 18 having a second surface, and a third support member 16. It consists of and. The first support member 17 and the second support member 18 may be made of the same material.

According to the configurations shown in FIGS. 3 and 4, since the distance between the first surface 14 and the second surface 15 is maintained at the time of pressurization, the thickness of the bonded portion can be set to a desired value.

FIG. 5 shows a state immediately before fixing the semiconductor device 10 (assembly) to the inside of the pressure bonding container.

In the figure, the semiconductor device 10 is installed on the upper surface of the second supporting member 18, and then the first supporting member 17 is arranged so as to cover the upper surface of the semiconductor device 10, and the first supporting member 17 is tightened with the bolts 55. The support member 17 of No. 1 is fixed.

FIG. 6 shows an installation process of the semiconductor device 10 in a modified example of the pressure bonding container of FIG.

In the figure, the semiconductor device 10 is sandwiched between two slide plates 61, and these are inserted into the jig 20. The material of the slide plate 61 is preferably the same as that of the first support member 17 and the second support member 18, or a material having higher elastic modulus and thermal expansion coefficient than those. Further, it is preferable that a plurality of devices can be installed at once in consideration of manufacturing efficiency.

The first support member 17 and the second support member 18 require a certain amount of thickness in order to increase the rigidity, but if the volume increases, it takes time to raise the temperature. In consideration of such a problem, the member forming the jig 20 is made of, for example, H steel so that the temperature rises in a short time while maintaining the rigidity. Is preferably provided. It may have a structure with a thinned inside such as a truss structure or a honeycomb structure. The third support member 16 preferably has a columnar shape with a cross-sectional area as small as possible so that heat can be uniform.

According to the present embodiment, pressure heating bonding can be realized without using a complicated jig.
(Third Embodiment)
FIG. 7: is sectional drawing which shows 1 process of the manufacturing method of the assembly which is the 3rd Embodiment of this invention.

In this figure, a cushioning member 19 such as a resin sheet is arranged between the semiconductor device 10 and the first surface 14. Similarly, the cushioning member 19 may be arranged between the semiconductor device 10 and the second surface 15. As a result, it is possible to add effects such as damage alleviation of the semiconductor device 10, homogenization of surface pressure distribution, and gap adjustment. In addition, it becomes possible to absorb height variations when pressing a plurality of devices at once.

FIG. 8 is a graph showing the stress-strain relationship of the cushioning member 19 of FIG. 7.

As shown in FIG. 8, it is desirable to use, as the cushioning member 19, a material having a stress-strain relationship in which the stress does not increase with respect to the strain when the yield stress is exceeded. As a result, the pressure applied to the semiconductor device 10 does not rise above the yield stress of the buffer member 19, so that it is possible to control the pressure variation due to the height variation and the like. As such a material, for example, a foamed material, a material in which fillers or fibers are oriented in the thickness direction of a resin, or the like can be applied. Further, as an example of the resin, polyimide can be cited.

According to the present embodiment, it is possible to suppress variations in pressure due to variations in height and the like.

FIG. 9 collectively shows the main steps of the method for manufacturing an assembly of the present invention.

In this figure, first, an object to be processed containing a bonding material is arranged so as to be sandwiched between a first supporting member and a second supporting member (S1). The object to be processed is an assembly product before bonding, in which a bonding material containing fine metal particles is sandwiched between the first member and the second member. Next, the object to be processed is heated in a state where the first support member and the second support member are fixed so as to maintain the distance between them (S2). By heating in this manner, the bonding material sandwiched between the first member and the second member receives a force against thermal expansion, is compressed, and is sintered.

As described above, the joining method and joining apparatus according to the present invention can realize pressure joining only by heat treatment without using a complicated pressure mechanism.

It should be noted that the above-described embodiments are specifically described to help understanding of the present invention, and the present invention is not limited to having all the configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, a part of the configuration of each embodiment can be deleted, replaced with another configuration, or added with another configuration.

10: semiconductor device, 11: first member, 12: second member, 13: bonding material, 14: first surface, 15: second surface, 16: third support member, 17: first Support member, 18: second support member, 19: buffer member, 20: jig, 21: upper lid, 22: lock mechanism, 23: heater, 25: heat insulating material, 51: first support member, 52: Second support member, 55: bolt, 61: slide plate.

Claims (13)

A method for producing an assembly including a first member and a second member and having a joint between them by pressurizing and heating,
The first support member is provided between the first support member and the second support member by sandwiching a bonding material containing metal fine particles between the first member and the second member. And the second support member are sandwiched so as to maintain a distance between them, and the distance is maintained by the size of the first support member, and the first support member is fixed by a lock mechanism. The dimension of the first support member corresponds to the depth of the recess of the first support member,
Using the compressive stress from the first support member and the second support member, which heats the first member, the second member, and the bonding material, and suppresses thermal expansion of these at the time, A method for manufacturing an assembly, comprising applying pressure to a bonding material, thereby sintering the metal fine particles of the bonding material to form the bonding portion. Said between said second support member or between the assembly of the assembly and said first support member, the buffer member is located, the manufacturing method according to claim 1 Symbol placement of the assembly. The method for manufacturing an assembly according to claim 1, wherein the first support member and the second support member have a contact portion. It said second support member is a heater, the manufacturing method of assembly according to any one of claims 1-3. Around the assembly is surrounded by a heat insulating material, a method of assembly manufacturing according to any one of claims 1-4. The manufacturing of an assembly according to claim 1, further comprising a step of sandwiching the assembly between two slide plates and then inserting them between the first support member and the second support member. Method. The assembly is a semiconductor device, a method of assembly manufacturing according to any one of claims 1-6. When manufacturing an assembly including a first member and a second member and having a joint between them, a joining material containing fine metal particles, which becomes the joint, is used as the first member. A container used for pressurizing and heating while being sandwiched between the second member,
A first support member, a second support member, and a lock mechanism,
The first member, the second member, and the bonding material are attached to the first support member and the second support so as to maintain the distance between the first support member and the second support member. It has a configuration that makes it possible to hold it by sandwiching it with a member,
The distance is maintained by the dimensions of the first support member, the first support member being fixed by the locking mechanism ,
The pressure-bonding container , wherein the dimension of the first support member corresponds to the depth of the recess of the first support member . The pressure-bonding container according to claim 8 , wherein a buffer member is arranged on the inner surface of the first support member or the second support member. An apparatus for manufacturing an assembly including a first member and a second member and having a joint between them by pressurization and heating,
With the bonding material containing the metal fine particles sandwiched between the first member and the second member, these are placed between the first support member and the second support member. The support member and the second support member are arranged so as to be sandwiched so as to maintain a distance therebetween, the distance is maintained by the size of the first support member, and the first support member is locked by a locking mechanism. Fixed,
The dimension of the first support member corresponds to the depth of the recess of the first support member,
Using the compressive stress from the first support member and the second support member, which heats the first member, the second member, and the bonding material, and suppresses thermal expansion of these at the time, A pressure bonding apparatus that pressurizes a bonding material, thereby sintering the metal fine particles of the bonding material to form the bonding portion. A furnace for charging the first support member and the second support member with the first member, the second member, and the bonding material disposed between the first support member and the second support member in order to perform the heating; The pressure bonding apparatus according to claim 10 . The pressure bonding apparatus according to claim 10 , wherein a heater for heating is attached to the first support member or the second support member. The pressure bonding apparatus according to claim 10 , wherein the second support member is a heater for performing the heating.

Images