JPS5921171B2 - How to seal semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sealing a semiconductor device, and particularly to a method for sealing a semiconductor device in which surface protection is important.

First, the currently used method of vacuum packaging a semiconductor device will be described with reference to FIG.

The semiconductor device 1 is disposed on one side of a base 4 having terminals 2 and an exhaust hole 3, the outer edge of the base 4 and the outer edge of a concave metal container 5 are tightly joined by welding, and then the exhaust hole is closed. 3, the inside of the container 5 is evacuated, and then the exhaust hole 3 is sealed off by crimping or the like. Note that 6 is a conductive wire that connects the semiconductor device 1 and the terminal 2. Such a vacuum sealing method is similar to the method for sealing vacuum tubes in metal containers, which increases the cost of the container and is also inconvenient for mass production. In order to eliminate the above-mentioned disadvantages, the present invention has the following features:
An object of the present invention is to provide a method for sealing a semiconductor device suitable for mass production by providing a through hole in the semiconductor device.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 2 and 3 illustrate an embodiment of the present invention, in which 11 is a plate-shaped insulating base made of ceramic or the like, which serves as a concave container with a concave portion 12 provided therein; A metal layer 13 as a conductive wire is provided on the surface by a method such as printing.

The flat semiconductor device 14 is mounted so that the surface 15 to be protected on which elements and the like are disposed corresponds to the recess 12 of the base 11. A through hole 16 is formed through the semiconductor device 14, and solder bumps 17 are provided at terminals for the elements on the protective surface 15 of the semiconductor device 14. A comparative method for forming the through holes 16 in the semiconductor device 14 is to coat the front and back surfaces of the semiconductor device 14 with ordinary photoresist, form a pattern of the necessary through holes, and then perform chemical etching from the front and back sides at the same time. This is a practical method. Now, in order to seal the semiconductor device 14 having the above structure, first the protective surface 15 of the semiconductor device 14 is placed in the recess 1 of the base 11.
The base 11 and the semiconductor device 14 are installed corresponding to the base 11 and the semiconductor device 14 by sealing their respective outer edges with glass powder or the like by thermal melting or the like.
maintain airtightness between

Next, the combination of the base 11 and the semiconductor device 14 is placed in a vacuum container and the exhaust work begins. can be exhausted. The recess 12 of the base 11 is evacuated through the through hole 16 of the semiconductor device 14 . Here, the upper edge of the through hole 16 is chamfered into a dish shape, a metal layer is applied to that surface, and a sealing body 18 made of solder or glass is installed in the dish-shaped part. This is very convenient for the subsequent sealing process. The details of this part will be described later.
Next, the above-mentioned combined object is evacuated through the through hole 16. If the combined object has a sealing body 18 on the upper edge of the through hole 16, the upper edge of the through hole 16 and the sealing body are removed. body 18
The shape must be such that the exhaust resistance is small.

After the evacuation is completed, the through hole 16 is sealed by heating and melting in the vacuum container, or the upper edge of the through hole 16 and the sealing body 18 are heated and melted to seal the through hole 16 hermetically. As a heating method, heat, light irradiation, induction heating using a coil, etc. can be used. FIG. 3 shows a state in which the opening is hermetically sealed by the sealing body 18. In this way, the base 11
This means that the functional element portion of the semiconductor element 14 is completely sealed. By the way, a small volume of the recess 12 of the base 11 is sufficient, and this type of sealing method is particularly useful when many functional elements and circuit networks are integrated on a large-area insulating substrate, such as in a hybrid integrated circuit device. This is a particularly effective sealing method in some cases. Furthermore, it is optional to provide additional packaging to the outer surface of the semiconductor device for protection. Now, the through hole 16 of the semiconductor device 14 mentioned earlier
The sealing body 18 will be described in detail.

FIG. 4 shows a sectional view of a main part of the semiconductor device 14, and 19 is a plate portion formed at the upper edge of the through hole 16. As shown in FIG. 5 and 6 are perspective views of the semiconductor device 14 and the sealing body 18, and the inner surface of the dish portion 19 is coated with a metal-plated film made of nickel or the like. Sealing body 1 during exhaust work
Since exhaust is performed through the gap between the plate 8 and the dish portion 19, the shape of each must be formed so as to reduce the exhaust resistance. When a spherical sealing body 18 is used, the exhaust resistance can be reduced by forming the plate 19 into a pyramid shape as shown in FIG. 5, or a petal shape as shown in FIG. do. Further, when the dish portion 19 is formed into a conical shape, it is desirable to use a cube, a tetrahedron, or the like as the sealing body 18. FIG. 7 shows another embodiment of the present invention, which shows a method for vacuum-sealing a semiconductor device as a pressure sensor using a sealing body.

In the figure, reference numeral 21 denotes a base made of an insulating material such as ceramic as a concave container having a concave portion 22, and the outer edge of a semiconductor device 26 having a through hole 23 and resistance layers 24 and 25 is connected to the container 21. The joint part 27 is formed by the outer edge of the glass, etc.
is sealed. 28 is a metal layer for connecting the resistance layers 24 and 25, and 29 is an external lead line.

It is desirable for the pressure sensor to have as uniform an amount of strain as possible due to the stress applied to the semiconductor device 26 from the viewpoint of strength and measurement. It is also better to separate them from the resistance layers 24 and 25 as much as possible. Therefore, it is necessary to form a groove 30 in the substrate 21 that connects the through hole 23 and the recess 22. By providing the groove 30, the concave portion 22 is evacuated via the groove 30 and the through hole 23, and after the evacuation operation, the dish portion at the upper edge of the through hole 23 is melted with a sealing material to seal it airtight. The pressure sensor hermetically sealed as described above can be used as an absolute pressure sensor because the recess 22 is in a vacuum, and the resistance layer 2
Pressure measurement is performed by applying negative pressure to 4.

FIG. 8 is a diagram showing still another embodiment in which the present invention is applied to a pressure sensor, in which the same parts as in FIG. 7 are given the same numbers.

A base 21 made of an insulating material such as ceramic as shown in FIG. 8 has two recesses formed therein. The lower recess 22 is a space for the vacuum mentioned above, and the upper recess is a space for semiconductor devices. It is a space to store 26. The semiconductor device 26 and the base 21 are hermetically sealed at a joint 27.
The sealing work in this embodiment is easier than in the previous embodiment. Furthermore, since the base 21 has a two-tiered concave structure, the combined surface of the semiconductor device 26 and the base 21 has the advantage of being flat. The device of this embodiment has a through hole 31 independent of the through hole 23, and the through hole 2
3 is the same as the resistance layer 24 by depositing the metal layer 28.
5 can be connected to the resistance layer 25 and the external lead wire 29 by similarly covering the metal layer 28 to the through hole 31.
and can be connected. Semiconductor device 26 and base 21
The groove may be formed between the lower part of the through hole 23 and the recess 22 if they are joined so that the through hole 31 can be sealed. After forming the combined object as described above, the inside of the recess 22 is evacuated through the through hole 23 and the groove 30, and then the dish portion at the upper edge of the through hole 23 is sealed by melting. The pressure sensor hermetically sealed as described above can also be used as an absolute pressure sensor by applying negative pressure to the resistance layer 24 in the same manner as in the previous embodiment.

In the embodiments described so far, a method has been described in which the inside of the concave container is evacuated, but the present invention is not particularly limited to this. This is also a possible method.

As explained above, after the outer edge of the semiconductor element having through holes on the front and back surfaces and the outer edge of the concave container are closely joined together, the interior of the concave container is evacuated through the through hole, and then the through hole is The method for sealing a semiconductor device of the present invention, which is characterized by sealing a hole, can protect the semiconductor device with a simple concave container having a small-volume concave portion, thereby reducing the cost of the container and providing an exhaust passage in the semiconductor device itself. Moreover, since it has a through hole that can be easily sealed, it is suitable for mass production because it can exhaust a large amount of semiconductor devices, and the through hole can be used as an electrical connection path between the front and back sides.
It is particularly effective for hermetically sealing hybrid integrated circuits, and has extremely high industrial value.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a structure when a conventional semiconductor device is hermetically sealed, FIGS. 2 and 3 are views showing an embodiment of the method for sealing a semiconductor device of the present invention, and FIGS. 6 shows a sealing portion of a through hole, FIG. 7 shows another embodiment of the method for sealing a semiconductor device according to the present invention, and FIG. 8 shows a further example of the method for sealing a semiconductor device according to the present invention. It is a figure which shows another Example. 11, 21... Base, 12, 22...
Recessed portion, 13, 28... Metal layer, 14, 26...
... Semiconductor device, 16, 23, 31 ... Through hole, 27 ... Joint part, 29 ... External lead wire.

Claims (1)

[Claims] 1. After closely joining the outer edge of a semiconductor element having a through hole between the front and back sides and the outer edge of a concave container, the inside of the concave container is evacuated through the through hole, and then the through hole is sealed. Characteristic method for sealing semiconductor devices.