JPH0347673A - Solder surface joining method and semiconductor integrated circuit device using its method - Google Patents

Abstract

PURPOSE:To prevent the generation of a void caused by a fact that bubbles remain behind on the joint surface by using a solder perform which consists of solder of plural different compositions, and melted and diffused, and becomes a desired composition in an equalized state. CONSTITUTION:Plural joining objects 1, 2 are joined through solder. Therefore, they are joined by inserting a solder preform 5 between the joining objects 1, 2. The solder preform 5 is constituted of solder of plural different compositions, that is, low melting point solder 5a and high melting point solder 5b, and by melting and diffusing it, a desired composition is obtained in an equalized state. Subsequently, on each joint surface of the joining objects 1, 2, metallized layers 3, 4 are formed and joined through the solder preform 5. In such a way, the generation of a leak path in a sealing part can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a solder surface bonding technique and a semiconductor integrated circuit device using the same, and in particular, to a method for reducing heat transfer resistance and improving airtightness in a solder surface joint. Regarding effective techniques such as

[Conventional technology]

For example, in the manufacturing process of large-scale logic integrated circuit devices that constitute general-purpose computer systems, individual semiconductor pellets on which semiconductor integrated circuits with desired functions have been formed are packaged, for example, in hermetically sealed microchip carriers. By enclosing this package inside a sealing structure consisting of a larger module base and module camp, etc., it is possible to improve packaging density and simplify the cooling mechanism for semiconductor pellets that generate heat during operation. It is known to achieve improvements in efficiency and efficiency.

By the way, as an example of the sealing form of the semiconductor pellet with respect to the microchip carrier, the following can be considered.

That is, as shown in FIG. 11, the semiconductor pellet 7) 300 is fixed in advance to the package base 100 via the solder bump 200, and the sealing surface between the package base 100 and the cap 400, and is the cap 40 facing the back side of the semiconductor pellet 300
Preliminary solder with a predetermined --like composition is applied to the inner surface of the cap 400, and heated while the sealing surfaces of the pan cage base 100 and the cap 400, the back surface of the semiconductor pellet 300, and the inner surface of the camp 400 are in close contact with each other. By doing so, the preliminary solder is melted and fused to ensure the airtightness of the sealed portion between the package base 100 and the cap 400, and the solder formed between the back surface of the semiconductor bezel 7) 300 and the inner surface of the cap 400 is This layer ensures a heat dissipation path.

Further, a solder bump 500 is formed on the outer surface of the package base 100, and the puff cage base 100
Electric signals are exchanged between the internally sealed semiconductor layer yh300 and the outside through a multilayer wiring structure (not shown) formed inside the board and solder bumps 200, and mounting on a board such as a module base is performed. be exposed.

Furthermore, in another technique disclosed in Japanese Patent Application Laid-Open No. 61-125025, a plurality of holes are formed in the thickness direction of the eutectic metal material when bonding a semiconductor chip to a semiconductor chip mounting substrate via the eutectic metal material. At the same time, with the semiconductor chip and the semiconductor chip mounting substrate stacked together via the eutectic metal material, the atmosphere is made into a vacuum state to form vacuum cavities inside the plurality of holes. After heating to about the melting point of the eutectic metal, an inert gas is introduced to break the vacuum state of the atmosphere, and the pressure difference between the vacuum cavity and the outside inert gas cloud surrounds the semiconductor chip. Semiconductor chips and semiconductor chips are mounted using a eutectic metal layer with no residual air bubbles (voids) by crushing the vacuum cavity with melted eutectic metal at the same time as it is brought into close contact with the mounting substrate, without applying external force from tools etc. to the semiconductor chip. The aim is to achieve bonding with the substrate.

[Problem to be solved by the invention]

However, in the case of the former prior art, since the composition of the preliminary solder is -11 over the entire area of the sealing part and the joint part, melting occurs simultaneously in each part during heating.
Air bubbles generated in the center of the joint surface have no place to escape and become trapped, making it easy to form voids.

As a result, in the solder layer that is interposed between the back surface of the semiconductor pellet and the inner surface of the cap and serves as a heat conduction path, the voids increase the heat transfer resistance and reduce the efficiency of heat dissipation from the semiconductor pellet to the cap side. This gave rise to the problem of
In addition, in the solder layer interposed in the sealing area between the package base and the cap, a leak path is likely to be formed through voids, which deteriorates the airtightness of the microchip carrier in which the semiconductor pellet is encapsulated. occurs.

On the other hand, in the case of the latter conventional technique, it is effective when the bonded portion is exposed to the external atmosphere, but as in the case of the microchip carrier shown in FIG.
In a sealing form in which an internal thermally conductive joint surrounded by this sealing part is formed at the same time, there is a concern that the molten solder layer interposed in the sealing part will be destroyed due to the pressure difference between the inside and outside. Application to carrier assembly processes is difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a solder surface joining method that can reliably prevent the generation of voids in the solder surface joints of objects to be joined.

Another object of the present invention is to provide a solder surface bonding method that can reduce the occurrence of leak paths due to poor fusion of the sealing portions.

Still another object of the present invention is to provide a semiconductor integrated circuit device in which the occurrence of voids in the sealed portion of the envelope, the heat dissipation adhesive portion, etc. is prevented, and the reliability of operation is improved.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Three Problems] Among the inventions disclosed in this application, a brief overview of typical inventions is as follows.

That is, the solder surface bonding method according to the present invention is a solder surface bonding method in which a plurality of objects to be bonded are bonded via solder, and is made of a plurality of solders having different compositions, which are melted and diffused into a uniform state. A solder preform having a desired composition is used.

Further, the solder surface joining method according to the present invention is a solder surface joining method in which a plurality of objects to be joined are joined via solder, in which a first material made of a high melting point component of solder is applied to the bonding surfaces of the objects to be joined. Preliminary solder having a three-layer structure in which a layer is sandwiched between a second layer made of a low melting point component of solder is applied, and the objects to be bonded are bonded by fusing the preliminary solder.

Further, the semiconductor integrated circuit device according to the present invention has a structure in which at least one of the sealing part and the heat dissipation bonding part of the envelope in which the semiconductor integrated circuit element is encapsulated has the following features.
Alternatively, the solder surface bonding method described in 7 is used.

[Effect]

According to the solder surface joining method of the present invention described above, for example,
By interposing a solder preform between the objects to be welded, the central part of the main surface facing the object to be joined is made of low melting point solder and the peripheral area is made of high melting point solder, so that when heating during bonding, the low melting point solder is first A molten region is formed in the center of the joint surface, and the molten region gradually expands outward, so that the gas present in the gap between the joints spreads from the center to the outer periphery. The waves of the low melting point solder are reliably expelled to the outside of the bonding surface, and the generation of voids due to residual air bubbles on the bonding surface can be reliably prevented.

Further, according to the above-described solder surface joining method of the present invention, during the heat treatment, the boundary portion of the preliminary solder where the low melting point second layers are in contact with each other, and the boundary portion between the preliminary solder and the object to be joined where the second layer is in contact with each other. Since melting starts from the boundary, it is possible to ensure the fusion of the preliminary solder boundary and the boundary between the preliminary solder and the object to be joined, and to reliably prevent the occurrence of leak paths in the sealed portion due to poor fusion. can.

Further, according to the semiconductor integrated circuit device of the present invention described above, the generation of voids in the sealing part of the envelope in which the semiconductor integrated circuit element is encapsulated, the adhesive part for heat dissipation, etc. is reliably avoided, so that the heat dissipation is prevented. Overheating of the semiconductor integrated circuit element due to an increase in heat transfer resistance at the adhesive part and deterioration of airtightness due to a leak path formed in the sealed part of the envelope are avoided, and operational reliability is improved.

[Example 1] Hereinafter, an example of a solder surface bonding method which is an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a joint portion schematically showing an example of a solder surface joining method according to an embodiment of the present invention, and FIG.
FIG. 3 is a perspective view showing the main parts thereof.

For example, Cr-Cu-Au or Ti
A metallized layer 3 and a metallized layer 4 having a three-layer structure such as -N1-Au and W-N1-Au are formed to improve wettability with solder, which will be described later.

A plate-shaped solder preform 5 is held between the objects 1 and 2 during bonding.

In this case, as shown in FIGS. 1 and 2, the solder preform 5 interposed between the objects 1 and 2 is metallized by the objects 1 and 2.
3 and 4 are formed and the central part of the main surface facing the joint surface is made of low melting point solder 5a, and the peripheral part surrounding this low melting point solder 5a is made of high melting point solder 5b.

That is, the solder preform 5 is made of, for example, Pb/
In the case of Sn-based solder, a solder with a composition ratio of Pb and Sn of +f7;3 or 4:6 is used as the low melting point solder 5a in the center, and as the high melting point solder 5b in the periphery. For example, 95:5 or (more than:1) solder is used.

Then, in a state where both are uniformly fused, Pb:
! :Sn is highly melted with the low melting point solder 5a constituting the solder preform 5 so that the composition ratio of Sn is 9:1, for example, suitable for the intended use of solder surface bonding.

Set the amount of solder 5b.

An example of the operation of this embodiment will be described below.

First, the solder preform 5 having the structure described above is sandwiched between the objects 1 and 2 to be bonded, and the temperature is raised to a target temperature while applying a predetermined pressing load to bring them into close contact.

At this time, when using a solder preform with a similar composition as in the past, melting begins almost simultaneously in the entire area of the joint, so the gas that had accumulated in the internal gap becomes trapped in the joint. There is concern that this could lead to the formation of harmful voids.

On the other hand, in the case of this embodiment, in the temperature rising process, melting starts from the low melting sound solder 5a in the central part, which has a lower melting point, in the solder preform 5, and the melting starts from the low melting sound solder 5a in the central part, which has a lower melting point. In addition to contributing to bonding, heat sales of the components occur due to the concentration difference between the low melting point solder 5a and the high melting point solder 5b by melting, and the high melting point solder 5 in the peripheral area in contact with the low melting point solder 5a.
Since the melting point of b gradually decreases, the melted region gradually expands from the center of the solder preform 5, that is, the center of the joint, toward the outer periphery.

As a result, objects to be joined 1 and 2 and solder preform 5
The gas remaining in the gap between the solder and the solder is pushed out by the solder, which spreads from the center to the outer periphery, and is reliably removed from the joint, thereby reliably preventing voids from forming at the joint. be done.

In the molten state, the low melting point solder 5a and the high melting point solder 5
b and melt together uniformly to form solder with the desired composition,
The bonded portion between the objects 1 and 2 to be bonded can have desired physical properties such as strength.

As a result, for example, when the objects 1 and 2 to be bonded are semiconductor bere-soto 300 and camp 400 shown in FIG. There is no increase in heat transfer resistance from the design value of the semiconductor beam 7) from 300 to camp 4.
Heat dissipation to the 00 side is ensured, and the semiconductor plate 7) 300 is prevented from overheating during operation.

Further, when the objects 1 and 2 to be bonded are the package base 100 and the camp 400 shown in FIG. The airtightness of the envelope is improved, and corrosion of the semiconductor pellet 7) 300 due to moisture intrusion from the outside is reliably prevented.

This improves the operational reliability of a semiconductor integrated circuit device configured by enclosing the semiconductor pellet 300 in an envelope such as a microchip carrier.

[Embodiment 2] FIGS. 3 and 4 are a sectional view and a perspective view schematically showing a solder surface bonding method according to another embodiment of the present invention.

That is, in the case of the second embodiment, the solder preform 6
As such, a solder region 6b and a solder region 6C whose melting points are changed in multiple stages are provided between a low melting point solder 6a having a melting point M6a in the center and a high melting point solder 6d having a melting point M6d in the outermost periphery. M6b and melting point M6c are M6cl>M6
c>M6 b>M6a.

As a result, in the case of the second embodiment, the melting region expands from the center to the outer periphery of the solder preform 6 during the temperature raising operation, so that the same effect as in the first embodiment can be obtained. Obtainable.

[Embodiment 3] FIGS. 5 and 6 are a schematic sectional view and a perspective view schematically showing an example of a solder surface bonding method according to yet another embodiment of the present invention.

In the case of the third embodiment, the thickness of the low melting point solder 7a in the center part of the solder preform 7 is set to the thickness of the high melting point solder 7a in the peripheral part.
The thickness is larger than that of b.

As a result, the low melting point solder 7a in the center protrudes from the surrounding high melting point solder 7b, and when the objects 1 and 2 are overlapped via the solder preform 7, the objects 1 and 2 Since the solder preform 7 is in contact with the metallized layers 3 and 4, the melting from the low melting point solder 7a constituting the center part of the solder preform 7 and the expansion of the melted area are performed more reliably, which is different from the case of the first embodiment. A similar effect can be obtained.

[Embodiment 4] FIG. 7 is a sectional view schematically showing an example of a solder surface bonding method according to yet another embodiment of the present invention.

In the case of the fourth embodiment, a so-called crand material is used as the solder preform 8, which is a plate-shaped high melting point solder 8b and a low melting point solder 8a bonded to the center of both the front and back surfaces.

As a result, melting starts from the low melting point solder 8a in the center when the temperature rises, so the same effect as in the first embodiment can be obtained, and by using a clad material as the solder preform 8, the solder preform 8 It has the advantage of reducing manufacturing costs.

Note that the clad material is not limited to the three-layer structure shown in FIG. 7, but may have a four-layer or more structure as shown in FIG. 8. That is, in the case of the figure, as the solder preform 9, low melting point solder 9 whose melting point and area gradually decrease is placed in the center of both main surfaces of the plate-shaped high melting point solder 9d.
It uses a clad material made by stacking and bonding layers c, 9b, and 9a.

[Embodiment 5] FIG. 9 is a partially cutaway perspective view showing an example of a solder surface bonding method according to still another embodiment of the present invention.

In the case of the fifth embodiment, the objects 1 and 2 to be bonded are, for example, the Pancaen base 100 shown in FIG.
and a cap 400 are shown.

That is, in this case, the solder preform 10 takes on a frame shape in accordance with the shape of the sealing part, but in the present embodiment 5, the solder preform IO has a frame shape with a wide width and a high melting point. Along the center of both main surfaces of the solder tab,
Similarly, a narrow frame-shaped low melting point solder 10a is pasted together.

As a result, over the entire length of the sealed parts of the package base 100 and the cap 400, which are the objects 1 and 2, the low melting point solder 10a located at the center of the sealed parts spreads in both directions inside and outside the package. , it is possible to prevent the generation of voids due to residual air bubbles in the sealed portion.

As a result, τ↓ is formed by connecting multiple voids, etc.
- The airtightness of the envelope such as the microchip carrier is improved, and corrosion of the semiconductor pellet 300 due to the intrusion of moisture from the outside is reliably prevented.

[Embodiment 6] FIG. 10 is a sectional view showing an example of a solder surface bonding method according to still another embodiment of the present invention.

In the case of the sixth embodiment, for example, P b /S r
In the case of + type solder, the high melting point component Pb or p
A second layer 11 made of Sn, which is a low melting point component, is sandwiched between the central first layer 11a made of an alloy containing Sn in b.
b and 11C are formed to serve as preliminary solder 11.

The preliminary solder 11 can be formed using, for example, the pan cage base 100 and the carrier.

Sn and Pb are alternately vapor-deposited on the metallized layer 3a (4a) of the metallized layer 3a (4a) of the metallized layer 400, or S
There are methods such as applying a cladding material using n as a covering material.

As a result, the package base 100 (camp 40
The package base 100 and the camp 400 are in contact with the metallized layer 3a (4a) of 0) and for assembly.
When these are overlapped, the second layers 11C, which are the uppermost layers of the preliminary solder 11, are in contact with each other.

When heating is performed for sealing in this state, the second layer 11C with a low melting point and the metallized layer 3a (4a) forming the boundary between the preliminary solder 11 of the package base 100 and the cap 400 come into contact with each other. second layer 11
Melting starts from part b.

As a result, for example, when the preliminary solder 11 is composed of solder with a uniform composition, the occurrence of poor fusion at the boundary between the preliminary solder and the like is reliably prevented, and the sealing area between the package base 100 and the cap 400 is reliably prevented. This prevents the formation of leakage baths that impair the airtightness.

As a result, Package Base 100 and Camp 4
The performance of maintaining airtightness in an envelope such as a microchip carrier that is formed by sealing 00 to each other is improved, and the semiconductor integrated circuit device that is formed by encapsulating a semiconductor pellet 300 in the microchip carrier is improved. Operational reliability is improved.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, as solder for interconnecting objects to be bonded, P
It is not limited to b/Sn type or Au/''Sn type, but may be one using other low melting point □ metals.

In addition, as solder, P b /S n type and A u
/ It is not limited to binary alloys such as Sn-based alloys, but may be ternary or higher alloys.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

That is, according to the solder surface bonding method of the present invention, a plurality of objects to be bonded are bonded via solder. Since we use a solder preform that has a desired composition depending on the condition, for example, a solder preform whose main surface facing the objects to be welded has a low melting point solder in the central part and a high melting point solder in the peripheral part is placed between the objects to be welded. By intervening the solder, during heating during bonding, a molten region is first formed in the center of the joint surface made of low melting point solder, and the molten region gradually expands outward, causing gaps in the joint, etc. The gas present in the bonding surface is reliably expelled from the bonding surface by the waves of low melting point solder that spread from the center to the outside, thereby reliably preventing the generation of voids due to residual air bubbles, etc. on the bonding surface. I can do it.

Further, according to the solder surface joining method of the present invention, a plurality of objects to be bonded are bonded via solder, wherein the bonding surface of the objects to be bonded is coated with a high melting point component of the solder. depositing a preliminary solder exhibiting a 31 structure in which a first layer consisting of the above solder is sandwiched between a second layer consisting of a low melting point component of the solder;
Since the objects to be joined are bonded by fusing the preliminary solder, during the heat treatment, the boundary portion of the preliminary solder where the second layer with a low melting point is in contact with each other, and the preliminary solder and the object to be joined where the second layer is in contact are Melting begins at the boundary between the pre-solder and the object to be welded, ensuring that the pre-solder and the pre-solder interface with the object to be welded are fused, reliably preventing the occurrence of a leak bath at the sealing part due to poor fusion. be able to.

Further, according to the semiconductor integrated circuit device of the present invention, at least one of the sealing part and the heat dissipation adhesive part of the envelope in which the semiconductor integrated circuit element is sealed includes the following claims 1, 2, 3, 4,
Since the solder surface bonding method described in 5.6 or 7 is used, the generation of voids in the sealing part of the envelope in which the semiconductor integrated circuit element is sealed, the heat dissipation adhesive part, etc. is reliably avoided, and the heat dissipation adhesive part Overheating of the semiconductor integrated circuit element due to an increase in heat transfer resistance in the semiconductor integrated circuit element and deterioration of airtightness due to a leak path formed in the sealed portion of the envelope are avoided, and operational reliability is improved.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of a joint portion schematically showing an example of a solder surface joining method according to an embodiment of the present invention, Fig. 2 is a perspective view showing the main parts taken out, and Fig. 3 is a diagram of the present invention. Embodiment 2 A schematic cross-sectional view of a joint portion schematically showing an example of a solder surface bonding method according to Embodiment 2, FIG. 4 is a perspective view showing the main parts taken out, and FIG. FIG. 6 is a schematic cross-sectional view of a joint portion schematically showing an example of a solder surface bonding method, FIG. 6 is a perspective view showing the main parts thereof, and FIG. 8 is a schematic sectional view showing a modified example thereof; FIG. 9 is a perspective view showing an example of a solder surface bonding method according to Embodiment 5 of the present invention; FIG. 10 is a schematic sectional view showing a modification thereof; FIG. 11 is a cross-sectional view showing an example of the solder surface bonding method according to the sixth embodiment. FIG. 11 is a diagram showing an example of the sealing structure of a semiconductor integrated circuit device. 1.2... object to be joined, 3, 4.3a, 4a... metallized layer, 5... solder brief ohm, 5a... low melting point solder, 5b... high melting point solder, 6...・Solder preform, 6a...Low melting point solder, 6b, 6c...Solder area, 6d...High melting point solder, 7...Solder preform, 7a...Low melting point solder, 7b... High melting point solder, 8.
...Solder preform, 8a...Low melting point solder, 8b.
...High melting point solder, 9...Solder preform, 9a...
・Low melting point solder, 9d...High melting point solder, 10...Solder preform, 10a...Low melting point solder, 10b...
High melting point solder, 11... Preliminary solder, 11a... First layer, ltb, IIC... Second layer, 100... Package base, 200... Solder bump, 300...
Semiconductor pellet, 400...Camp, 500...
Handa bang. Figure 5

Claims (1)

[Scope of Claims] 1. A solder surface joining method for joining a plurality of objects to be joined through solder, which comprises a plurality of solders of different compositions, which are melted and diffused to be uniform in a desired composition. A solder surface joining method using a solder preform. 2. The solder surface joining method according to claim 1, wherein the center portion of the main surface of the solder preform facing the object to be joined is made of low melting point solder, and the peripheral portion is made of high melting point solder. 3. The solder according to claim 2, wherein the low melting point solder is thicker in the central part of the main surface of the solder preform facing the object to be joined than the high melting point solder in the peripheral part. Face-to-face meeting method. 4. The solder preform according to claim 1, wherein the solder preform is formed by attaching a plate-shaped low-melting-point solder to the center of the main surface of the plate-shaped high-melting-point solder facing the object to be joined. Solder surface joining method. 5. A solder surface bonding method for joining a plurality of objects to be bonded via solder, wherein a first layer made of a high melting point component of the solder is applied to a bonding surface of the objects to be bonded using a low melting point component of the solder. 1. A method for joining solder surfaces, comprising: depositing preliminary solder having a three-layer structure sandwiched between second layers consisting of second layers, and fusing the preliminary solder to join the objects to be joined. 6. The solder surface joining method according to claim 5, wherein the preliminary solder exhibiting the three-layer structure is formed by vapor deposition or plating. 7. The preliminary solder exhibiting a three-layer structure is made of a cladding material exhibiting a three-layer structure in which a first layer consisting of a high melting point component of the solder is sandwiched between a second layer consisting of a low melting point component of the solder. The solder surface joining method according to claim 5, characterized in that: 8. At least one of the sealing part and the heat radiation adhesive part of the envelope in which the semiconductor integrated circuit element is sealed,
8. A semiconductor integrated circuit device using the solder surface bonding method according to 3, 4, 5, 6 or 7.