JPS6146972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a planar semiconductor device in which two or more PN diodes are formed in one pellet, and particularly to a separation layer for preventing unnecessary coupling between the diodes.

Generally, a semiconductor device in which a plurality of diodes are formed in a planar structure on one pellet (substrate) has a structure as shown in FIG. That is, in one N-type semiconductor substrate 1, a plurality of P layers 2 are formed by P-type impurities diffused from a plurality of diffusion windows formed in a silicon dioxide film 3.
a, 2b, ...... are anode layers, and an N-type substrate 1
are used as a common cathode layer, and each anode layer 2a, 2
Electrode metals _4a and _4b are respectively applied to b, . Further, depending on the case, an N ⁺ channel stopper 5 containing a high concentration of N type impurity is provided between each P layer.

FIG. 2 is an example circuit diagram of the use of two diode elements of the semiconductor device of FIG. 1, and in FIG.
The input AC applied between the terminals A ₁ and A ₂ through the input transformer 21 charges the capacitor 22 through the element 2a, and the voltage between the terminals of the capacitor 22 becomes K.
2-terminal PNPN connected in parallel between terminal and A _2- terminal
When the breakdown voltage of switch 23 is reached,
The two-terminal PNPN switch 23 is turned on, and the charge in the capacitor 22 is discharged through the primary side of the output transformer 24. The series resonance between the capacitor 22 and the primary coil of the transformer 24 is caused by two terminals.
Because of the anti-parallel connection of the PNPN switch 23 and the diode 2b, a reciprocating oscillation circuit is formed, so it can be maintained without any trouble, and the two of the transformer 24
Spark energy is supplied to the spark gap 25 of the next output. However, in the example of the use of the circuit of FIG. 2 of the conventional device of FIG. The injected holes form the P layer 2b and the N layer 1.
In some cases, the operation of the PNP transistor reaching the P layer 2b was absorbed by the reverse electric field of the PN junction between the two, and the expected circuit operation could not be obtained.

An object of the present invention is to provide a semiconductor device in which a plurality of diodes are combined into one pellet, which does not cause the parasitic transistor effect due to the coupling between the diodes.

FIG. 3 shows a semiconductor device of the present invention. In the present invention, a relatively deep P-type element isolation layer 6 is provided at the position where the channel stopper 5 of FIG. 1 is provided, and a shallow high-concentration N ⁺ An impurity layer 7 is provided, and the inter-element isolation layer 6 and the N ⁺ layer 7 are short-circuited by a metal electrode 8 on their upper surfaces.

In the semiconductor device of the present invention shown in FIG.
Holes injected from the layer 2a into the N layer 1 and directed toward the P layer 2b by diffusion through the common N layer 1 are captured by the element isolation P layer 6 on the way, and further
Since the junction is short-circuited at the upper surface, it is neutralized and disappears by electrons that enter the P-type element isolation layer 6 through this short-circuited portion. Therefore, since there are no holes that reach the P layer 2b as in the example of FIG.
Even if it is applied to a circuit as shown in the figure, it will not affect the operation of this circuit in any way.

In addition, in order to form the above-mentioned element isolation layer 6,
For example, the N ⁺ layer 7 is formed at the same time as the P layers 2a and 2b are formed, and the N ⁺ layer 7 is formed at the same time as the phosphorus glass layer is formed on the surface silicon oxide film, and the N The metal electrode 8 for PN junction short circuit between the layer 7 and the anode electrodes 4a, 4b...
Since it can be carried out at the same time as the formation of..., it can be done without any special increase in man-hours compared to the conventional manufacturing process.

In the semiconductor device of the present invention thus obtained, the distance between the diode elements was conventionally set wide in order to prevent parasitic transistor effects.
Even if this distance is narrowed, parasitic transistor effects can be prevented, so by narrowing the distance between diode elements, the area of one pellet can be reduced, increasing the yield of pellets per wafer and lowering the cost. can. Furthermore, the high concentration N ⁺ impurity layer not only annihilates holes, but also works effectively as a channel stopper between diode elements. As described above, the semiconductor device according to the present invention not only prevents coupling between elements within the same pellet, but also has a small size, which has an excellent effect of helping to reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a conventional semiconductor device including two diode elements in the same pellet, Fig. 2 is a usage example circuit diagram for explaining the parasitic transistor effect of the semiconductor device of Fig. 1, and Fig. 3 1 is a sectional view of one embodiment of the present invention. 1...N-type substrate (pellet), 2a, 2b...
Diode element or P anode layer, 3... Silicon oxide film, 4a, 4b... Metal electrode, 6... Element isolation P layer, 7... Channel stopper/contact N ⁺ layer, 8... Isolation P layer short circuit electrode.

Claims (1)

[Claims] 1 Comparison of a semiconductor device in which a plurality of regions of opposite conductivity type are formed on a semiconductor substrate of one conductivity type, in which a relatively deep element isolation layer of opposite conductivity type is formed between the regions of opposite conductivity type, and a PN junction is formed with the element isolation layer. 1. A semiconductor device comprising a single conductivity type layer with a shallow high impurity concentration, the PN junction being short-circuited by a metal electrode.