JPS62262451A - Semiconnductor integrated circuit - Google Patents

Abstract

PURPOSE:To increase the integration by means of forming a protective diode close to an input resistor in an island region containing the input resistor. CONSTITUTION:A P type isolated region 8 is formed by diffusion in an N-type epitaxial layer 1 to form an island region 9a forming various elements insulation-isolated from one another. An input resistor 3 is provided in the island region 9a to form a protective junction diode 5 close to a contact 4 in the input side of resistor 3. Thus, any high static voltage put on a terminal connecting to the input resistor 3 can be bypassed to a protective diode 5 to protect the elements inside an integrated circuit. Furthermore, the protective diode 5 can be formed in the island region 9a similar to the proper integrated circuit so that the space for an insulation-isolated region to be another island region may be saved.

Description

[Detailed Description of the Invention] [Summary] When providing a protective element for preventing electrostatic damage in a resistive input type semiconductor integrated circuit, a protective diode is formed in the same island region as the resistor and close to the resistor. By doing so, we aim to improve the degree of integration.

[Industrial application field]

The present invention relates to the structure of a protection element against electrostatic damage for a resistive input type semiconductor integrated circuit.

When semiconductor integrated circuits are handled, unexpectedly high static electricity is applied to the input terminals from the outside, which can destroy internal elements. For this reason, in conventional resistor input type semiconductor integrated circuits, an island region separate from the island region forming the input resistor and other elements and elements is formed, and a protective diode is formed in this island region. Since the island regions are formed separately, the area becomes large, which is disadvantageous in increasing the degree of integration, and improvement of this problem has been desired.

The present invention seeks to solve this problem.

[Conventional technology]

3(a) and 3(b) are schematic diagrams of a conventional electrostatic breakdown prevention structure for a semiconductor integrated circuit, with FIG. 3(a) being a top view and FIG. 3(b) being a sectional view.

In these figures, 1 is the first conduction type (here N type)
epitaxial layer with a second conductivity type (here P
An insulating isolation region 8 (type) is formed by diffusion to create island regions forming various elements that are insulated from each other.

In the island region 9a, an input resistor 3 formed by diffusing P-type impurities into an N-type region is provided. Furthermore, the Al wiring 7a from the input side contact 4 of the input resistor 3 to the input terminal is connected to a sinusoidal insulating film formed on the surface of the epitaxial layer l.
Provided on the g film 2. Also, the other end of the resistor 3 is a MOS Tr.
, or a semiconductor active element such as an old pTr is connected.

9b is an island region dedicated to a protection diode provided separately from the island region 9a. Two openings are made in the SiO□ film 2 on this region, and the contact 6a of one opening is made with P-type diffusion and N A PN junction diode 5 is formed between the epitaxial layer of the mold and the contact 6b of the other opening is filled with N.
The buried layer N'1 under the island region 9b performs the diffusion of
Connect it to 0.

A wiring 7a passes over the contact 6a and is connected to the positive electrode of the junction diode 5.

The contact 6b is provided with an AI wiring 7b and connected to Vcc, which is the maximum voltage (positive in this case) applied to this semiconductor integrated circuit.

The lower right diagram of FIG. 3(a) is a circuit diagram symbolically representing the structure. (The same is shown in Figures 1 and 2, which will be described later.) When excessive positive static electricity is input to the input terminal, the current flows to the junction diode 5 and is bypassed, so the elements after the resistor 3 are protected.

The junction diode 5 is in an OFF state for a normal value voltage when the integrated circuit is used.

In this way, in conventional semiconductor integrated circuits, the protection diode is formed in an island area separate from the island area for the original integrated circuit, so extra space is taken up in the isolation area, which increases the degree of integration. I didn't like it in that respect.

[Problem that the invention seeks to solve]

Functionally, it is the same as the conventional example, and by providing the protection diode in the same island region as the island region for the original integrated circuit that forms the input resistor, and close to the input side contact of the resistor, The aim is to improve the degree of integration.

[Means for solving problems]

The solution to the above problem is that in a semiconductor integrated circuit having an input resistance, the epitaxial layer (1) of the first conduction type region is
It is close to the input side contact (4) of the second conductivity type resistor (3) formed by diffusion in the insulating isolation region (8).
), the semiconductor integrated circuit according to the present invention has a protective diode (5) formed in the same island region (9a), and connects this protective diode (5) to a power supply applied to the semiconductor integrated circuit. It can be achieved.

In particular, the present invention can be easily implemented by making the diode (5) a junction diode in which a region of the first conductivity type and a region of the second conductivity type are diffused.

Furthermore, the protection diode (5) is a Schottky barrier diode formed by a region of a first conductivity type and a metal deposited on the opening of the insulating film (2) on the region of the first conductivity type. By doing so, the present invention can be easily implemented.

[Function] While handling a semiconductor integrated circuit, even if a large electrostatic voltage is applied to the input resistor connection terminal, it will be bypassed by the protection diode and the internal integrated circuit elements will be protected. Furthermore, since the protection diode is formed in the same island region as the original integrated circuit, the space taken up by the insulation isolation region when it is used as a separate island region can be saved, and the degree of integration can be improved.

〔Example〕

FIGS. 1(a) and 1(b) are schematic diagrams of an electrostatic breakdown prevention structure for a semiconductor integrated circuit in Example (1) of the present invention.
FIG. 1(a) is a top view, and FIG. 1(b) is a sectional view.

In these figures, parts with the same names as in FIG. 3 are designated by the same reference numerals.

In the figure, 1 is an epitaxial layer of the first conductivity type (here, N type), which is coated with a second conductivity type (here, P type).
The isolation regions 8 are formed by diffusion, and the isolation regions 8 are insulated and isolated from each other.
An island region 9a in which various elements will be formed is created.

In the island region 9a, an input resistor 3 formed by diffusing P-type impurities into an N-type region is provided. Further, a P-wall region for forming a protective junction diode 5 is provided close to the contact 4 on the input side of the input resistor 3, a contact 6a is formed in this, and both contacts 4 and 6a are covered to form an input terminal. A to reach
The wiring 7 of t is formed on the SiO□ film 2. Underneath the N-type epitaxial layer 1 there is a buried layer 10 of No, which is connected to a power source at or near the highest voltage Vcc applied to the integrated circuit. The connection diagram of this structure is the lower right diagram of Figure 1(a), which is completely different from the third
This is the same as in Figure (a).

FIGS. 2(a) and 2(b) are schematic diagrams of a structure for preventing electrostatic damage of a semiconductor integrated circuit in Example (2) of the present invention.
FIG. 2(a) is a top view, and FIG. 2(b) is a sectional view.

In this case, an opening is provided in the 5i02 film 2 adjacent to the contact 4 of the resistor 3, and an AI electrode wiring 7 is deposited thereon to form a Schittky barrier diode 5. Everything else is the same as the PN junction diode shown in FIG.

As shown in Embodiments (1) and (2) of the present invention, the protection function against static electricity is the same as that of the conventional device, and since the area can be reduced, the degree of integration can be improved.

Further, although the first conductivity type is N type and the second conductivity type is P type, these may be reversed. However, in this case, Vcc may be set to the highest negative voltage applied to the integrated circuit or a voltage close to it.

〔Effect of the invention〕

In a resistor input type semiconductor integrated circuit, the degree of integration can be improved by forming a protection diode in the same island region as the input resistor and close to the resistor.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are schematic diagrams of an electrostatic breakdown prevention structure for a semiconductor integrated circuit in embodiment (1) of the present invention. FIGS. Schematic diagram of the electrostatic damage prevention structure of the semiconductor integrated circuit in 2), Figure 3(a)
, (b) are schematic diagrams of a conventional electrostatic breakdown prevention structure for a semiconductor integrated circuit. (a) is a top view, and (b) is a sectional view. In these figures, 1 is an epitaxial layer (N type), 2 is a 5ift film, 3 is a resistor, 4 is a contact, 5 is a diode, 6a and 6b are contacts, 7 is a wiring (AI), and 8 is an isolation region (P wall area), 9a is an island area, 10 is a buried layer

Claims (1)

[Scope of Claims] [1] In a semiconductor integrated circuit having an input resistance, a first
the same island region adjacent to the contact (4) on the input side of the resistor (3) of the second conduction type formed by diffusion in the epitaxial layer (1) of the conduction type region and made of the isolation region (8); A protective diode (5) formed in (9a)
), and the diode (5) is connected to a power supply applied to the semiconductor integrated circuit. [2] The diode (5) is in a region of the first conductivity type,
2. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is a junction diode in which a region of the second conductivity type is formed by diffusion. [3] a region in which the diode (5) is of a first conductivity type;
The semiconductor according to claim 1, characterized in that it is a Schottky barrier diode formed by metal deposited in the opening of the insulating film (2) on the region of the first conductivity type. integrated circuit.