JPS6019673B2 - semiconductor equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device including at least one transistor (including special transistors such as phototransistors and FETs), and more specifically, the present invention relates to a semiconductor device including at least one transistor (including special transistors such as phototransistors and FETs), and more specifically, The present invention relates to a semiconductor device in which a gate electrode (or a gate electrode) is electrostatically shielded.

The transistor has an emitter electrode (or source electrode),
It is a well-known fact that a base electrode (or gate electrode) is provided outside the collector electrode (or drain electrode), and the three electrodes are usually used by connecting them to electrodes or electrical circuit components. There is.

In a normal emitter (or source) grounded circuit type, the base (or gate) electrode serves as the control electrode, the emitter (or source) electrode serves as the common electrode, and the collector (or drain) serves as the output electrode. Electrodes are used respectively. However, when used for special purposes (for example, when using a phototransistor as a light-receiving element and trying to obtain a large output current for a certain amount of light input), an electric current with an extremely high resistance value is attached to the base electrode. It may be used with a low resistor connected or without connecting any electrical circuit components to the base electrode, that is, with the base electrode open. In such cases, in conventional semiconductor devices, the base electrode functions as a so-called antenna, or acts as an input terminal for leakage current inside the insulator at or near the surface of the insulator covering the electrode. The disadvantage is that malfunctions are likely to occur.

One object of the present invention is to provide a high-performance semiconductor device that eliminates the above-mentioned drawbacks and is less likely to malfunction. Another object of the present invention is to obtain a semiconductor device whose cost can be reduced without losing the above-mentioned high performance.

According to the present invention, the base electrode (or gate electrode) of at least one transistor in various semiconductor devices
The first objective can be achieved by electrostatic shielding.

Further, according to the present invention, only the insulator provided between the conductive member for shielding and the base electrode (or gate electrode) has better airtightness and electrical insulation than the insulator in other parts. The second objective can be achieved by forming it from a material with excellent properties. Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a perspective view of an optically coupled semiconductor device comprising one light emitting diode and one light receiving transistor as an example of a subordinate semiconductor device. In the figure, 1 and 2 are the anode electrode and cathode electrode of the light emitting diode, respectively;
Reference numerals 3, 4 and 5 respectively indicate an emitter electrode, a base electrode and a collector electrode of the light-receiving transistor, 6 a metal container, and 7 an insulator. When a power source is connected to the electrodes 1 and 2 and the electrodes (usually several milliamps to several hundred milliamps) are connected, the diode is generated and a current corresponding to the input current is extracted from the electrode 3 or electrode 5 of the light receiving transistor. I can do it. The ratio of output current to diode input current is usually CTR (CmrentT
The CTR depends not only on the performance of the light-emitting diode and the light-receiving transistor, but also on the resistance value of the electric resistor connected to the base electrode 4 of the light-receiving transistor. is also affected. Generally, the larger the CTR value is, the more desirable it is, and for this purpose, it is necessary to make the resistance value extremely large or to not connect an electric low resistor to the base electrode (that is, to leave the base electrode open).

However, in any of these cases, the base electrode 4 acts as a so-called antenna, and there is a possibility that the semiconductor device may malfunction due to reception of some electrical signal present near the location where the optically coupled semiconductor device is used. there were. This drawback can be prevented to some extent by cutting the electrode 4 short and using it, but it is not completely possible, and if the surface of the insulator 7 becomes dirty or moisture adheres to the surface, the surface of the insulator 7 or The leakage current flowing through the inside of the insulator near the surface increases and the leakage current flows into the base electrode, which also causes the semiconductor device to malfunction.

This drawback was particularly noticeable in the case of molded semiconductor devices. FIG. 2 shows a perspective view of an optically coupled semiconductor device according to an embodiment of the present invention, and 1 and 7 are essentially the same as 1 to 7 shown in FIG.

In the figure, reference numeral 8 indicates a conductive layer formed on the surface of the insulator 7 so as to surround the base electrode 4 by coating or scattering, and reference numeral 9 indicates a conductive layer that is electrically connected to the conductive layer 8. Shows the grounding electrode. Note that, as is clear from the drawings, the base electrode 4 and the conductive layer 8 are electrically insulated. In this embodiment, even if the base electrode 4 is used in an open state, the electrode 4 is electrostatically separated from other electrodes by the ground potential conductive layer 8 provided on the surface of the insulator 7. Therefore, malfunctions due to leakage current on the insulator surface will not occur.

Moreover, if the base electrode 4 is cut short,
The antenna effect of the base electrode is reduced due to the shielding effect of the conductive layer, which has the advantage that malfunctions do not occur. Furthermore, this embodiment has the advantage that it is possible to immediately determine which current the base electrode corresponds to just by looking at the exterior. FIG. 3 shows a perspective view of an optically coupled semiconductor device according to another embodiment of the present invention, in which 1 and 7 are essentially the same members as explained in FIGS. 1 and 2.

In the figure, 10 indicates a round bar-shaped protrusion of the insulator, and the protrusion 1
0 is arranged concentrically with the outer diameter of the insulator, and a grounding conductive layer 18 is provided on its surface. Further, the center axis of the base electrode 4 is arranged so as to coincide with the center axis of the round bar-shaped protrusion ID. According to this embodiment,
The base electrode part is in the form of a so-called shielded wire or coaxial line, and is an optically coupled semiconductor that can both reduce the antenna effect and cut off leakage current as explained in the embodiment of Fig. 2, and therefore does not cause malfunction. It has the characteristic that a device can be obtained.

Furthermore, in this embodiment, since the base input impedance is reduced, there is no need to cut out the base electrode even when the base electrode is used in an open state, so that the work efficiency is improved.
Although the embodiment shown in FIG. 3 shows the case where the protrusions are arranged at the center of the insulator, it is not necessary to arrange them at the center, and the effect of the present invention can still be achieved even if the protrusions are arranged at any position. can be obtained. In addition, in the above embodiment, the case where the electrostatic shielding conductive part 8 or 18 is connected to or also serves as a grounding electrode is shown, but the present invention should not be limited only to the above case. For example, the same effect can be obtained even if the conductive member is connected to the emitter electrode (or source electrode).

FIG. 4 is a schematic cross-sectional view of a molded optically coupled semiconductor device according to still another embodiment of the present invention, and FIG. 5 is a side view of the front mounting device shown in FIG. 4, seen from the right side. 1 to 5 indicate essentially the same electrodes as 1 to 5 explained in FIGS. 1 to 3. In the figure, 11 is a lead wire that connects the anode and cathode 1 of the light emitting diode 20, and 13 and 14 are lead wires that connect the emitter and emitter electrode 3 of the light receiving transistor 30, and the base and base wires, respectively. 40 is an insulating material with excellent electrical insulation and airtightness; 60 is a relatively inexpensive electrical insulator that has good electrical insulation and airtightness, and transmits light generated by light emitting diodes (including light other than visible light such as infrared rays). Reference numeral 28 indicates a conductive member that is integrated with the emitter electrode 3 and surrounds the base electrode 4. According to this embodiment, since the insulator 40 surrounding the base electrode 4 has excellent insulation and airtightness, almost no internal leakage current occurs in the insulator.
Further, even if the surface of the insulator is contaminated with a conductive liquid or the like, surface leakage current from the collector electrode etc. is shielded by the electrostatic shielding conductive part 28 and does not flow into the base electrode 4.

Therefore, it is possible to prevent malfunction of the device due to leakage base input current caused by contamination of the mold material, which is a common problem in conventional molded optically coupled semiconductor devices. According to the present invention, the device has a performance comparable to that of a semiconductor device that uses a partially metal case, and because it is a molded device, the cost can be reduced. In this embodiment, a case has been described in which the conductive member 28 provided so as to surround the base electrode 4 is integrated with the emitter electrode 3. As in the embodiment shown, the section 23 may be provided independently of the emitter electrode.

Furthermore, in general, when a semiconductor device is contaminated with a liquid or the like, the conductivity inside the insulator of the device usually decreases exponentially from the surface of the insulator. It does not necessarily have to be made of a high-quality material, and the conductive member formed to surround the base electrode (or the base electrode) can be extended to some extent inside from the surface of the insulator on which the semiconductor device is formed. Even if you just set it up,
As long as the object of the present invention can be achieved, in short, according to the present invention, in a semiconductor device having at least one transistor, a conductive region is provided so as to surround the base electrode (or gate electrode) of the transistor. By connecting or integrating the conductive member with a grounding electrode or an emitter electrode (or source electrode), a high-performance semiconductor device without malfunction can be obtained.

In the above embodiment, only a cross-coupled semiconductor device has been described, but the present invention should not be limited to this, and may be applied to a base electrode (or a gate electrode) of a transistor that requires electrostatic shielding in various other semiconductor devices. Any one of the present invention or an appropriate combination of the present invention can be applied to the electrode).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a conventional optically coupled semiconductor device, FIGS. 2 and 3 are perspective views of one embodiment and another embodiment of the present invention, respectively, and FIG. 4 is a perspective view of a conventional optically coupled semiconductor device. FIG. 5 shows a side view of the embodiment shown in FIG. 4 as seen from the right side.

1 and 2 are respectively the anode electrode and the cathode electrode of the light emitting diode, 3, 4 and 5 are the emitter electrode, base fin electrode and collector electrode of the light receiving transistor, respectively, 6 is a metal container, and 7 is an insulator. , 8 and 18 are conductor layers, 9 is a grounding electrode, 10 is an insulator protrusion, 11, 1
2 and 13 are all lead wires, 2 rivers are light emitting diodes, 30 are light receiving transistors, and 60' are the aforementioned diode 2.
An insulator that transmits the light generated by 0, an insulator with excellent insulation and airtightness, an insulator for normal molding,
28 indicates a conductive member.

Figure 1 Multi 2 drawings Figure 3 Figure 4 Traditional map

Claims (1)

[Claims] 1. In a semiconductor device including a transistor with a control electrode in an electrically floating state, a conductive member is provided to surround the control electrode of the transistor, and the conductive member is electrically connected to a common electrode. A semiconductor device characterized by: