JPS6080273A - Semiconductor device of high withstand voltage - Google Patents

Abstract

PURPOSE:To obtain the characteristic of stable withstand voltage by a method wherein, when a semiconductor substrate serving as a collector is provided with a base region and an emitter region positioned therein into a bi-polar transistor, the element region is surrounded with a field limit ring of the conductivity type different from that of the substrate, and a conductor layer is provided thereon via insulation film. CONSTITUTION:The P type base region 2 is diffusion-formed in the surface layer part of the N type semiconductor substrate 1 serving as the collector, and the N type emitter region 3 is provided therein into the bi-polar transistor. Next, in addition, the P type field limit ring regions 4 and 5 surrounding the region 2 are perpendicularly diffusion-formed in the substrate at an interval, and an SiO2 film 10 is adhered from above these regions to the end of the region 2. Thereafter, Al films 8 corresponding to the regions 4 and 5 respectively are adhered by being positioned on the film 10, and an Al film 9 is provided at the end of the film 10 and connected to an N<+> type region 11 formed in the substrate at the end of the film 10. Thus, the penetration of external ions to the element region is blocked.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to high voltage semiconductor devices, and particularly to semiconductor devices such as high voltage transistors or diodes, thyristors, and try books formed by planar junctions.

In conventional high-voltage semiconductor devices, a field limit ring is used to increase the voltage resistance, and in addition, a nitride film or an organic material is layered on top of a thermal oxide film to ensure stability. Another method has been to protect the joint end with a glass-based material such as lead glass.

However, as voltage resistance increases, it has become clear that conventional structures using field limit rings and nitride films are unable to obtain sufficiently stable voltage resistance characteristics, and structures using glass-based materials have the disadvantage of being susceptible to temperature changes. It's here.

(3) Object of the Invention An object of the present invention is to provide a high voltage semiconductor device that does not have these conventional drawbacks, has stable voltage resistance characteristics, and is resistant to temperature changes.

(4) Structure of the Invention A feature of the present invention is that first and second or said first and second conductivity types having a conductivity type opposite to one conductivity type are formed by Breaner diffusion on at least one surface of a semiconductor substrate of one conductivity type. PNP or N having first and second diffusion layers and a third diffusion layer having a conductivity type opposite to this one in at least one of these diffusion layers.
Adjacent to each of the first and second diffusion layers of the PN three-layer structure, PNPN, or NPNP04-layer structure, a plurality of fourth diffusion layers surround these diffusion regions and have the same conductive layer as these.
and a fifth diffusion layer, and the exposed surface of at least one of the fourth and fifth diffusion layers is covered with a conductor (usually metal) such as aluminum through a surface protection film such as a thermal oxide film. .

The present invention prevents the intrusion and influence of external ions by covering with this conductor, and is suitable for life tests, environmental tests, etc.
This suppresses the increase in current and provides stable breakdown voltage characteristics.

(5) Examples and effects of the invention The present invention will be explained in more detail below with reference to the drawings.

FIG. 1 is a sectional view of the outer circumference of an NPN bipolar transistor. P-type base region 2 on Nfi semiconductor substrate 1
and an N-type emitter region 3, and P-type field limit rings 4 and 5 surrounding the base region 2.
An aluminum film 8 is laminated on the exposed surface portions of the field limit rings 4, 5 via a protective film 10 formed by laminating a thermal oxide film (810z) or a tinned film or the like thereon. This is formed at the same time as the aluminum lead electrodes 6 and 7 are formed, and no additional steps are added. An N+ region 11 is provided on the peripheral surface of the semiconductor substrate 1, and an aluminum film 9 extending from the surface of the oxide film 10 is deposited thereon.

In this way, by covering the field limit ring 4.5 with a conductive material such as aluminum, the influence on the electrical characteristics due to the intrusion of external ions is suppressed, and the collector
When a reverse voltage is applied between the bases, the depletion layer that spreads from the collector-base junction to the collector layer is not affected by external ions in the vicinity of the field limit rings 4 and 5, and stable breakdown voltage characteristics can be obtained.

Furthermore, the manufacturing process can be made in the same manner as the conventional process by simply changing the mask. In addition, since a thermal oxide film is used as the passivation film, effects such as resistance to changes in temperature can be obtained. If the aluminum film 8 on the field limit ring 4.5 is provided on the one 4 closest to the base region 2, it will be quite effective, and if it is provided on the field limit ring 5 outside of that, an even more perfect effect is expected. Ru.

Similarly, the structure in which an aluminum film is formed on the field limit ring can also be applied to a diode, and in this case, the structure is the same as the state in which the N-type emitter region 3 of FIG. 1 is not provided. Furthermore, it can be similarly applied to thyristors.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of an NPN bipolar transistor according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... N-type semiconductor substrate, 2... P-type base region, 3... N-type emitter region, 4, 5...
...P-type diffusion region (field limit ring)
, 6... Emitsu 9... Aluminum film, 10... Surface protective film (8102 or Si
N lamination).

Claims (1)

[Claims] a semiconductor region having a conductivity type opposite to the -conductivity type formed on the surface of a semiconductor substrate having one conductivity type; and an annular region having the opposite conductivity type formed on the semiconductor substrate around the semiconductor region; and a conductor layer formed on the annular region with an insulating film interposed therebetween.