JPS6130736B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device and a method for manufacturing the same, and in particular to a semiconductor device in which the surface of a PN junction is stabilized with a glass insulating film and metal protruding electrodes are formed locally, and the manufacturing thereof. Concerning improvements in methods.

A DHD (Double Heatsink Diode) type diode pellet has a structure as shown in FIG. 1, for example, and is manufactured by the following method. That is,
N-type silicon substrate 1 having a diffusion window 3 of an insulating film 2
In this step, P type impurities are selectively thermally diffused into the diffusion window 3 to form a P ⁺ type region 4, and a P ⁺ N junction 5 is formed in the N type silicon substrate 1. On the other hand, an N ⁺ type region 6 is formed on the other main surface by thermally diffusing N type impurities. Next, a cathode electrode 8 is formed on the entire surface of the N ⁺ type region 6, and the cathode electrode 8 is formed on the entire surface of the N + type region 6, and the
An anode electrode 7 is selectively formed on the P ⁺ type region 4 . Thereafter, a negative potential is applied to the anode electrode 7 portion to selectively build up the silver plating to form the protruding electrode 9, and form a diode pellet 10 as shown in FIG.
is obtained.

However, the diode pellet 10 with the above structure
When heat-sealed in a DHD type glass case, for example, because the slug lead material is a composite wire (the surface is coated with borax), it has special characteristics especially for high voltage products (over 100V). Deterioration is likely to occur.
The reason for this is thought to be that the sodium contained in the borax evaporates during glass sealing and the positive charge in the oxide film increases, resulting in a decrease in breakdown voltage. As a result, there were drawbacks such as a decrease in assembly yield and a decrease in reliability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor device having a glass insulating film as a surface stabilizing film and a method for manufacturing the same, which eliminates the deterioration of characteristics during glass sealing due to the conventional diode pellet structure described above. It is.

The feature of the present invention is that after forming a planar type PN main junction using an oxide film as a mask, the oxide film remains inside the PN junction edge and other oxide films are removed.
After covering the entire surface of the exposed silicon portion including the bonding end with a glass insulating film, a window was opened in a portion of the oxide film, and a metal layer and a raised electrode were formed in the window.

Next, a semiconductor device and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings.

Figures 2a to 2e show the DHD according to the present invention.
This figure shows the manufacturing process of shaped diode pellets. In FIG. 2a, an oxide film 12 is formed on an N-type silicon substrate 11 by a thermal oxidation method, a diffusion window 13 is bored by a photoetching method, and a P-type impurity is selected in the diffusion window 13 by a thermal diffusion method. spread,
N type silicon substrate 1 forming P ⁺ type region 14
A PN junction 15 is formed in 1.

Next, in FIG. 2b, an oxide film 12 is left on only a part of the P ⁺ type region 14 on one main surface of the semiconductor substrate by photoetching, and another layer is formed so as to expose the PN junction end 16. The oxide film 12 is removed by etching.

In FIG. 2c, glass particles containing borosilicate as a main component are selectively electrodeposited on the surface of the exposed silicon portion of the semiconductor substrate by, for example, electrophoresis to form a glass particle layer. Next, the semiconductor substrate is
The glass particle layer is melted by heating and baking at 500 to 800°C for about 1 to 2 hours to form a glass insulating film 17 with a thickness of about 10 to 20 microns.
Apply surface stabilization treatment.

Next, in FIG. 2d, a photoresist film is coated on one main surface of the semiconductor substrate, and a window 18 is formed in a part of the oxide film 12 on the P ⁺ type region 14 by photoetching. At the same time, the oxide film 12 on the other side is etched and removed. The upper oxide film 12 plays a major role in improving pattern accuracy in the next process of ohmic formation, and is also very important in preventing side etching of the glass insulating film 17 and improving the adhesion strength of the metal layer. be.

Next, in FIG. 2e, metal layers 19 and 19' are formed on the window 18 on one main surface of the semiconductor substrate and on the other surface by a general vapor deposition method. Next, a negative potential is applied to a portion of the metal layer 19 on the window 18 on one principal surface of the semiconductor substrate by electroplating to selectively build up silver plating, for example, to form the protruding electrode 20 to a height of, for example, 60 to 80 microns. A diode pellet 21 as shown in FIG. 2d is obtained.

FIG. 3 shows a mounting example in which a diode pellet (semiconductor device) 21 obtained according to an embodiment of the present invention is sealed in a glass sleeve having a DHD type electrode structure. Diode pellet 21 is attached to glass sleeve 2
Metal terminal 2 enclosed within 2 and arranged coaxially
3 and 24 are in pressure contact.

By fusing the inner wall of the glass sleeve 22 to the metal terminals 23 and 24, the diode pellet 21 can be hermetically sealed.

As described above, the present invention provides a plurality of diffusion windows in the oxide film on one main surface of a semiconductor substrate, and diffuses impurities of the opposite conductivity type to the substrate from these windows into the substrate to form a large number of planar PN junctions. forming a silicon surface, leaving only a part of the oxide film in the P ⁺ type region, and removing the other oxide film to expose the silicon surface so as to expose the PN junction end, and the PN junction end on the one main surface. A step of depositing a glass insulating film on the silicon exposed portion, and a step of providing a window in a part of the oxide film on the P ⁺ type region on the one main surface, and forming a metal layer on the window and the entire surface of the other surface. and a step of selectively forming protruding electrodes on the metal layer of the window, the glass insulating film is thick and stable as a surface stabilizing film, and does not form an interface with silicon like an oxide film. Because there is no movement of positive charges existing in the oxide film or imperfections in the oxide film, and because it is stable against external contamination, it is advantageous in generating high breakdown voltages. As a result, the assembly yield can be improved and a highly reliable semiconductor device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor device according to the prior art. FIGS. 2a to 2e are cross-sectional views showing an embodiment of the present invention in the order of steps. FIG. 3 is a cross-sectional view showing a case where a semiconductor device according to an embodiment of the present invention is mounted on a double heat sink. In the figure, 1, 11...N type silicon substrate, 2, 12... Oxide film, 3, 13... Diffusion window, 4, 14...P ⁺ type region, 5, 15... PN Junction, 16... PN junction end, 17... Glass insulating film, 18... Window, 19, 19'... Metal layer, 20
... Protruding electrode, 21 ... Diode pellet, 2
2...Glass sleeve, 23, 24...Metal terminals.

Claims (1)

[Claims] 1. An opposite conductivity type region provided on one main surface of a semiconductor substrate of one conductivity type, and exposed on the one main surface of a PN junction formed of the semiconductor substrate and the opposite conductivity type region. a glass insulating film covering the end portion of the insulating film, an insulating film provided on the opposite conductivity type region, a hole provided in the insulating film reaching the one principal surface, and a metal provided in the hole. A semiconductor device comprising a film and a protruding electrode on the metal film. 2. A step of selectively forming an opposite conductivity type region from one main surface of a semiconductor substrate of one conductivity type, and a step of leaving an insulating film on a part of the opposite conductivity type region and removing the other insulating film, a step of covering the one principal surface from which the insulating film has been removed with a glass protective film; a step of drilling a window in a part of the insulating film; and a step of depositing a metal layer on the window; 1. A method of manufacturing a semiconductor device, comprising: forming a protruding electrode layer.