JP2527630Y2 - Semiconductor device - Google Patents

Description

[Detailed description of the invention]

[0001]

Description of the Field of the Invention The present invention relates to an electrode structure of a semiconductor device such as a diode and a transistor.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view of a conventional PN junction type semiconductor device (chip) and its assembly explanatory diagram. In FIG. 1, 1 is a semiconductor substrate (N), 2 is a P type region, and 3 is a junction J. SiO ₂ or Si ₃ N ₄ as passivation, 4 is a soldering metal (ohmic metal such as Ni or Cr), and 5 is a solder. In order to assemble this chip with high reliability against temperature stress such as solder heat resistance, temperature cycle, and intermittent energization, as shown in FIG.
It is a well-known fact that a certain part is secured and absorbed against temperature stress. However, in the axial type, the lead bottom may come into direct contact with the metal for soldering due to the weight of the lead wire 6, variation in processing of the lead wire, and variation in assembly. (C) is a view showing that a part of the lead is in contact with the soldered metal due to the unevenness at the bottom of the lead. When the above stress is applied to these elements,
Cracks C may be formed on the contact surface and the PN junction characteristics may be impaired.

[0003] The applicant of the present invention has previously proposed the structure shown in FIG. 2 in order to improve the above problem. This structure shows an example applied to a Schottky barrier diode. In the drawing, 7 is a Schottky metal such as molybdenum (Mo), 8 is a metal layer (A1) softer than a lead wire and having a higher melting point than solder.
In the above structure, the expansion and contraction of each material due to the temperature stress was absorbed by the solder.
Is to replace the solder.

[0004]

In this structure, it has been confirmed that A1 can be used as a substitute for soldering to obtain reliability against extremely high temperature stress. However, since A1 is exposed on the chip surface, the moisture resistance is inferior. There are drawbacks. The reason for this is that a chlorine-based substance is present inside the package and absorbs the moisture that has entered the package, which becomes a solution and corrodes A1, and A1 flows out into the insulating film 3. When the corrosion of A1 occurs, A1 flows out into the insulating film, and a current easily flows on the insulating film, and there is a problem in reliability.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a diode for soldering both ends of a chip with a structure capable of improving a temperature stress resistance and a humidity resistance.

[0006]

FIG. 3 is a sectional view showing the structure of an embodiment of the present invention and shows an example of a PN junction type semiconductor device. In the present invention, the surface of the metal layer 8 such as A1 which absorbs the thermal stress is prevented by covering the periphery of the metal layer 8 with an insulating layer 9. With this configuration, by covering A1 with the insulating layer 9, it is possible to prevent the chlorine-based substance from adhering.
Corrosion is prevented. Incidentally, the manufacturing method of this structure will be described. First, the insulating film 3 (Si
O ₂ film performs formed by etching the PSG film). Next, an A1 film 8 having a thickness of 3 μm is formed on the entire surface by evaporation, and the substrate is etched at 450 to 500 ° C. in an N ₂ atmosphere for 15 minutes.
Anneal for about a minute. Further, an insulating film 9 (PSG) is formed on the entire surface.
A film is formed and etched to cover A1. Finally, to facilitate contact with the solder, a film thickness of 450
A Cr—Ni film 4 of 0 to 5000 ° is formed, and then soldering is performed.

FIG. 4 shows another embodiment of the present invention applied to a Schottky barrier type semiconductor device.

[0008]

According to the semiconductor device of the present invention, after A1 is formed, after-coating A1 with an insulating film prevents after-corrosion, which is effective in improving reliability.

[Brief description of the drawings]

FIG. 1 is a structural view of a conventional apparatus.

FIG. 2 is a structural view of a conventional device.

FIG. 3 is a sectional view showing the structure of the embodiment of the present invention;

FIG. 4 is a structural view of another embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 P-type region 3 oxide film 4 metal for soldering (ohmic metal) 5 solder 6 lead wire 7 Schottky metal (Mo) 8 metal layer (A1) 9 insulating layer

Claims (1)

(57) [Scope of request for utility model registration] 1. A semiconductor device in which an electrode portion of a semiconductor substrate having a Schottky junction or a PN junction is connected to a lead wire or a connector via solder, between the electrode portion and the lead wire or the connector. A semiconductor device, comprising: a metal layer softer than a material of the lead wire or the connector and having a higher melting point than the solder; and an insulating layer provided over an end of the metal layer.