JPS5917542B2 - Hermetically sealed assembly method for semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hermetically sealed assembly method for semiconductor devices, and is particularly effective when applied to large-scale integrated circuits.

2. Description of the Related Art The size of semiconductor devices tends to gradually increase due to improvements in their functionality and manufacturing technology, as seen in devices for large-scale integrated circuits.

However, the size of the ceramic container used to store it is standardized, except in special cases, for reasons of compatibility and workability. When the seal portion is removed, the size of the remaining island portion on which the semiconductor element is to be placed is naturally limited by its upper limit, which causes problems when attempting to mount a large-sized semiconductor element. Normally, in order to mount a semiconductor element on a metal plate, the metal plate is plated with Au, and an alloying reaction occurs between it and the Si material of the semiconductor element, using Au-Si alloy or Au-Sn alloy as a brazing material. A method is used to generate This mounting method is less likely to cause defects such as peeling or damage of the semiconductor element after mounting because the metal material of the semiconductor element and the island part, such as Kovar, has a coefficient of thermal expansion similar to that of RO and has good wettability. This is an excellent mounting method.
However, this alloying reaction cannot easily occur simply by raising the temperature of the metal or alloy used above the melting point of 5, and it is necessary to simultaneously apply mechanical vibrations.

Therefore, when a large semiconductor element is mounted on the island portion formed by the metallized layer in which the inner diameter of the ceramic wall member is maximized, no alloying reaction can occur. In this case, an expedient method may be used in which the semiconductor element is mounted in advance on a metal plate such as Kovar, and the entire metal plate is glued to the island part.
It is clear that exposing semiconductor devices to high temperatures more than once will adversely affect the functionality of the semiconductor devices. There is also an attempt to pre-deposit Au on the back side of the semiconductor element and accelerate the alloying reaction with as little mechanical vibration as possible30, but this results in a poor yield of elements from the wafer and high costs. Not widely used.

In view of the above circumstances, the present invention aims to provide a hermetically sealed assembly method suitable for large-sized semiconductor devices, and is capable of reducing the area of the island portion without causing mounting defects such as detachment from the island portion or damage. A full-sized semiconductor device can be hermetically sealed.

A detailed explanation will be given below based on examples.

FIG. 1 is a diagram showing an embodiment of the present invention.

A semiconductor element 2 is mounted in advance on a metal piece 1 such as Kovar plated with Au. This mounting method is
Since it is possible to apply sufficient mechanical vibration to the element, Au
An alloy reaction method using alloy brazing materials such as -Si, Au-Sn, etc. can be directly applied. In this way, metal piece 1
The semiconductor device 2 mounted on the ceramic wall member 3
A weld ring 6 and a metal piece 1 are inserted from the direction of the arrow into a ceramic container having a laminated structure of cubes and 4 and equipped with an external lead wire 5, and are brazed to the end face of the wall member 4 via a metallized layer. 14 times. At this time, instead of seam welding, it is also possible to use local heating means such as laser welding and electron beam welding. In addition, when the semiconductor element 2 is mounted on the metal piece 1 in advance, the entire surface of the metal piece 1 or Au-Sn alloy flowed to at least the hermetically sealed part, A
It is also possible to seal the metal pieces by bringing them into contact with a u-Si alloy brazing material and utilizing an alloying reaction caused by local irradiation with a laser beam or an electron beam.

FIG. 2 is a cross-sectional view showing an example of a semiconductor device obtained by the method of the present invention.

The subsequent assembly process of the present invention can be carried out in the same way as in the conventional assembly method, by connecting the wires using thin metal wires 8 and seam-welding the metal cap 9 to the weld ring 7 to achieve an airtight seal, or of course, by any other means. Hermetic sealing also does not hinder the implementation of the present invention. The shape of the metal piece 1 can be a flat plate as in the above embodiment, or it can be deformed into a trapezoidal shape as shown in FIG. The trapezoidal one is metal piece 1
The material of the metal piece also has the advantage of making it easier to connect with the thin metal wire 8 because it reduces the level difference between the bonding surface of the wall member 4 and the semiconductor element 2. is not limited to Kovar, but also Cu, N
It may be made of materials such as i, Fe. In that case, in order to alleviate the difference in thermal expansion coefficient and other characteristics with the semiconductor element 2,
It is preferable to mount a metal plate such as Kovar or the like by inserting it between the semiconductor element and the semiconductor element. Furthermore, by using local heating means for joining the metal plates 1, large-scale elements such as large-scale integrated circuits can be assembled with a minimum number of heating steps. Furthermore, it is quite natural that the present invention can be implemented for small devices as well. Further, the present invention provides an effective structure for attaching a heat sink 10 to a metal piece 1 as shown in FIG. As the material of this heat sink, in addition to metals such as Kovar, materials with good thermal conductivity such as beryllia can be freely selected. Furthermore, a structure in which a leg 11 is provided and can be bonded to a desired external lead as shown in FIG. 5 is effective when the ground pin is freely selected. Of course, the adhesion to the external lead wire can be achieved by using a known means for providing a metallized layer.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a cross-sectional view of a semiconductor pot device obtained by the present invention, and FIG. 3 is a modification of the semiconductor-sealed metal plate according to the present invention. Figure, Figure 4 and Figure 5
The figure is an example of an application of the present invention. 1...Metal piece, 2...Semiconductor element, 3
, 4... Ceramic wall member, 5... External lead wire, 6, 7... Weld ring, 8...
...Metal thin wire, 9...1...Metal cap, 10.
...Heat sink, 11...1...foot.

Claims (1)

[Claims] 1. A semiconductor element is bonded in advance to a semiconductor-sealing metal plate, and the semiconductor element is inserted into a through-hole in an island portion of a ceramic container that is large enough to fully accommodate the semiconductor element, and a metal provided around the through-hole is inserted. 1. A method for assembling a semiconductor device in an hermetically sealed manner, characterized in that the metal plate is applied to the chemical layer for local hermetically sealing, then bonding is performed with a thin metal wire, and then a cap is placed on the layer for hermetically sealing.