JPS5961954A - Semiconductor resistance element - Google Patents

Abstract

PURPOSE:To obtain a pinch resistor as to enable to control a current to flow at breakdown time by a method wherein a second diffusion resistance layer the same conductive type with a first diffusion resistance layer is continuously connected to the low electric potential side of the first diffusion resistance layer as the diffusion layer united in one body of both. CONSTITUTION:A first p type base diffusion resistance layer 4 is formed on the surface of an island region 2 consisting of an n type epitaxial layer, an n<+> type emitter diffusion layer 5 is provided at a part of the surface thereof to convert the p type diffusion layer 7 positioning directly thereunder into high resistance, the second p type diffusion resistance layer 8 is continuously connected being united in one body to the low electric potential side (the L side) of the p type diffusion layers 4, 7, and electrodes H, L to be connected respectively ohmically to the high electric potential side (the H side) and the low electric potential side are provided. The resistance value of the first p type diffusion layer 4 converted into high resistance is designated as R1, the resistance value of the second p type diffusion layer 8 continuously connected to the low electric potential side is designated as R2, and when a breakdown voltage is applied between the electrodes H and L, because resistance is divided into R1 and R2, a reverse bias voltage applied to p-n junction of the n<+> type layer 5 and the p type layer 4 is restrained under the breakdown voltage. Moreover, even when breakdown is generated, because the R2 component survives, the current can be controlled.

Description

[Detailed description of the invention] The present invention relates to a high resistance element using a semiconductor diffusion layer.

2. Description of the Related Art In semiconductor integrated circuit devices, a resistance element is known that utilizes a base diffusion layer of a transistor within an island region of a semiconductor substrate as a part of the circuit. This diffusion resistance is due to the fact that the base diffusion concentration is relatively high and the area of the semiconductor island region is limited.

Since high resistance cannot be obtained as is, a pinch resistance using emitter diffusion may be considered. As shown in FIGS. 1 and 2, this pinch resistance consists of a p-type Si 7%5 layer epitaxially grown on a p-type S1 (silicon) substrate 1.
In one of the n-type regions isolated from the others as an island region by type diffusion isolation/layer 3, a p-type ambiguous resistor layer 4 having a specific pattern using base diffusion of a transistor is formed.
form.

Next, an n+ type scattering layer 5 is formed across a part of the surface of the p type diffused resistance layer 40 using emitter diffusion. In the figure, 6 is an insulating film made of silicon oxide (SIOT), etc., and H and L are i (aluminum) electrodes that make ohmic contact with both ends of the diffused resistor.As shown, the p-type amended resistor 4 is a part of it. n+ type scattered layer 5 formed in
Therefore, the resistance area becomes narrower, and a high resistance part is attached to the part (pitch part) 7 directly under the n-type diffusion layer. In such a diffused resistance, the portion of the n+ type diffusion layer 5 protruding from the p type diffusion layer 4 is in contact with the epitaxial n type layer 2, so that the 2n+ type diffusion layer 5 and the n type layer 2 are It is at position m.

By the way, in the same figure, when the electrode [1 side is set to a high potential and the T end side is set to a low potential, the γ ratio potential difference of the resistance increases.

When the withstand voltage (e.g. 7V) or higher, the low potential side p
Breakdown occurs in the depletion layer 8 in the type layer, and H
It has been found that there is a risk that an unlimited current flows between f, L and b, and the circuit may be destroyed.

The present invention has been made to eliminate the above-mentioned drawbacks, and its object is to provide an improved pinch resistor that can control the current during breakdown.

As one embodiment of the present invention, FIGS. 3 and 4 show a semiconductor resistance element formed as a part of an IC. This semiconductor resistance element has an island region 2 made of a Y taxial n-type layer.
A first p-type base diffused resistor FVJ4 is formed on the surface of 0 (−
1 An n++ emitter diffusion layer 5 is formed on a part of the surface of this p-type diffusion.
In the semiconductor resistance element in which the p-type diffusion layer 7 directly under the p-type diffusion layer 7 is made to have high resistance, a second p-type diffusion resistance layer 8 is provided on the low potential side (LIBj) of the high-resistance p-type diffusion layer 4.7. are integrally connected, and ohmic connections H and L are provided on the high potential side (H side) and the low potential side, respectively.

In such a semiconductor resistor structure, the resistance value of the first p-type diffusion layer 4 including the high resistance portion (7) is set to 1.7. Assuming that the resistance value of the second p-type amended layer 8 connected to the low potential side is Imo, the breakdown/m pressure (
For example, if 7v) is θ), the resistance is also R2
Since it is divided into + type layer 5 and p type J'f! j 4
The reverse bias voltage applied to the pn junction should be kept below the breakdown voltage (for example, 3 to 4 V) so that breakdown does not occur. Even if breakdown occurs, the R2 component remains, so the current is controlled. be able to.

As described above in the embodiments, according to the present invention, the current can be controlled even during breakdown by adding one resistance to the low potential side of the p-type diffused resistor, which has a higher resistance than the n+ type diffused layer. This makes it possible to widen the range of pinch resistance.2 Therefore, the above-mentioned objective of obtaining high resistance with a limited semiconductor chip area can be achieved.

The invention is not limited to the above embodiments. In other words, the resistor pattern can have various forms other than this.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a conventional semiconductor resistance element. FIG. 2 is a sectional view taken along the line AN in FIG. 1. FIG. 3 is a plan view showing an example of a semiconductor resistance element according to the present invention. FIG. 4 is a sectional view taken along line B-8' in FIG. 3. l... pilJJ, Si i plate, 2... epitaxial n-type layer. 3... Isolation p-type layer, 4... (1st))
p-type diffused resistance layer, 5...n+ type tolerance layer, 6... insulating film. 7...V/T resistance section, 8...Second p-type diffused resistance layer. Agent Patent Attorney Usui 1) Yukisho Tori Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] 1. A semiconductor resistance element in which a high concentration diffusion layer having a conductivity type different from that of the first diffusion resistance layer is provided on a part of the surface of the first diffusion resistance layer formed on the surface of the semiconductor substrate. A semiconductor resistance element characterized in that a second diffused resistance layer of the same conductivity type as the first diffused resistance layer is successively provided on the low potential side of the first diffused resistance layer. 2- The semiconductor resistance element according to claim 1, wherein the first diffusion resistance layer and the second diffusion resistance layer are formed as an integrated diffusion layer. 3. The first and second diffusion resistance layers are used as base diffusion layers of transistors formed on the surface of the same semiconductor substrate, and the high concentration diffusion layers of different conductivity types are the same (patent that uses an emitter diffusion layer). A semiconductor resistance element according to claim 1 or 2.