JPS5890780A - Input protection device - Google Patents

Abstract

PURPOSE:To contrive the phenomenon that the ability of input protection is not more deteriorated as the input voltage goes high, by providing a dielectric substance having dielectric constant higher than that of the substance on the other region under the wiring from an external lead-out electrode to a diffused layer. CONSTITUTION:Under a part of the wiring provided among the input external lead-out electrode 15, a semiconductor substrate 11 and the inversed conductive type diffused layer 12, the dielectric substance having dielectric constant higher than that of the peripheral oxide film, e.g., Si nitride 16 is provided, and thereby a capacity 207 is added. Thus, since the capacity 207 which is not dependent on the voltage impressed on the input terminal 201 is provided on the wiring from the external lead-out electrode 201 to the diffused layer 207, even when spike- formed input overvoltage is impressed on the terminal 201, it is turned smooth by the delay due to the capacity. Therefore, the function as input protection can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an input protection device for a semiconductor device.

1#! Three-edge gate turtle field effect transistor (hereinafter referred to as MO8I)
It is abbreviated as llr. ), when connecting the external extraction electrode and the gate (1i1) pole of the input MO8Tr, there is a risk that the gate insulating film of the manually operated MO8Tr will be destroyed due to excessive voltage due to static electricity being applied to the external terminal. be. To prevent this, a protection circuit is usually provided between the external lead-out pole and the gate electrode.

Taking an N-channel type MO8Tr as an example, a plan view of the most commonly used input protection device in the past is shown in FIG.
A sectional view of A' is shown. FIG. 2 shows a value circuit of the input protection device shown in FIG. 1. As is clear from Figure 2, the operating principle of this input protection device is to delay the pressure waveform to smooth out the excessive resistance and capacitance IK applied to the multi-input terminal, and to smooth out the pressure waveform of the diode between the diffusion layer and the substrate. By using the forward and reverse characteristics, the input positive overvoltage is suppressed to the reverse breakdown voltage, and the input excessive voltage is suppressed to the forward voltage of the diode.

However, in conventional input protection devices, the junction valley t generated between the diffusion layer and the semiconductor substrate is used as the capacity of the guarantee circuit, so the higher the voltage applied to the input terminal, the more depleted the junction becomes. The layer widens 9 and the contact valley 'lIi becomes smaller. Therefore, in conventional input protection circuits, the ability to delay the waveform of the voltage applied to the input terminal decreases as the voltage applied to the input terminal increases, resulting in a deterioration of the input protection ability, which is very inconvenient. .

The present invention provides an input protection circuit that does not have the above-mentioned conventional drawbacks.

The present invention provides - conduction t/1. A reverse conductivity type diffusion layer formed on a type semiconductor substrate is connected to an external lead-out single pole for input and an input insulation group)
In the input protection circuit provided between the gate electrode of the field effect transistor, the input external extraction electrode and im
c Reverse conduction kW diffusion - % sign of the installation of an electric material that has a larger electrocardial rate than dielectric materials in other areas on the wiring placed between n Next An embodiment of '2#-Kabutomei will be described with reference to the drawings.

FIG. 3(a) is a plan view of the embodiment of the present invention, and FIG. 3(b) is a blood cut diagram of FIG. 3(!L) OB-B'. Figure 4 is the Teragawa circuit diagram of Figure 3. Conventional photoetching, thermal diffusion,
An input protection device having the structure shown in FIG. 3 can be produced using vapor phase growth and metal deposition techniques. External input drawer/#jIL
Under a part of the wiring provided between the electrode 15, the semiconductor substrate, and the reverse conductivity type diffusion layer 12, a dielectric material having a higher electric constant than the surrounding oxide film, such as silicon nitride 16, is placed. By installing this, the capacity 1207 in FIG. 4 is added.

Although not shown in FIG. 3, it is clear that the capacity can also be added by arranging the heterogeneous visiting materials in a multi-layered structure.

The operating principle of the input protection circuit according to the present invention is almost the same as that of the conventional input protection circuit. Since the capacitor 207 is installed, even if a spike-like input overvoltage is applied to the input terminal 201, the delay due to the capacitance and weight will be smooth.This has the effect of enhancing the input protection function compared to conventional input protection circuits. . Further, although the valley cover 207 is installed between the diffusion layer 202 and the gate electrode 205 as shown in FIG. 4, it is more effective if it is installed between the external extraction electrode 201 and the diffusion layer 202 as in this patent.

Although not shown in FIG. 3, the effect will be even greater if an impurity of four conductivity types is provided on the surface of the substrate in the region where the capacitor 207 is provided, and is located on the same side as the substrate.

The above is N-channel aluminum goo) MO8T r
′? Although the explanation was given using MO8T as an example, any other formation of MO8T
It is clear that this can also be applied to r.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are a plan view and a sectional view taken along line A-A' of a conventional input protection circuit, and FIG. 2 is an equivalent circuit diagram thereof.
3(a) and (b) are a plan view and a sectional view taken along line 13-B' of an embodiment of the present invention, FIG. 4 is a circuit diagram thereof,
Demeru. In addition, 1.11...P-type semiconductor substrate, 2.12...N-type semiconductor substrate% 13...
...Nitride #i element, 4.14... Connection hole, 5
．． 15...External lead-out aluminum electrode, 5', 1
5'... Aluminum wiring to the gate electrode of MOS Tr, 101, 102... Input terminal,
102,202,106.206...Resistance, 1
03.203,207... Capacity, 104,20
4...Diode, 105.205-...
Input MO8Tr. It is.

Claims (1)

[Claims] In an input protection device in which a reverse conductivity type diffusion layer formed on a single-conducting turtle-type semiconductor substrate is provided between an input external lead electrode and a gate 'IL electrode of an input insulated gate field effect transistor, the input external side lead electrode Under the wiring provided between the pole and the opposite conductivity type diffusion layer, a material having a higher electrical resistance than the electrolyte material in other areas is installed.
Features an input protection device.