JPH11204807A - Schottky junction diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid flowing unwanted leak currents to a Schottky diode and load, by using a metal having a comparatively low work function for an anode metal electrode and a metal having a higher work function than the anode metal electrode for a current blocking metal electrode. SOLUTION: A current blocking metal electrode 16 is made of a metal having a comparatively low work function. Hence, when a signal from a signal source takes '0' in binary notation, a depletion layer expanding from an input film 7 to the island part 3 can be expanded enough to run across the island part 3, if the cross sectional area of an island part 3 is widened to flow a high current to a load through a Schottky junction diode. When the signal from the signal source takes '0' in binary notation, hence unwanted leak current cannot be flowed to the Schottky diode and load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Schottky junction diode that can be used to control the supply of current to a load.

[0002]

2. Description of the Related Art Conventionally, a Schottky junction diode described below with reference to FIG. 7 has been proposed. That is, the n-type low-resistance semiconductor substrate 1 for the cathode and the n-type
An n-type semiconductor layer 2 formed on the low-resistance semiconductor substrate 1 and having an island 3 on the side opposite to the n-type low-resistance semiconductor substrate 1 for a cathode.

Then, on the surface of the island portion 3 of the n-type semiconductor layer 2 opposite to the n-type low-resistance semiconductor substrate 1 side for the cathode,
An anode metal electrode 4 is provided so as to form a Schottky junction 5 with the island-shaped portion 3 of the n-type semiconductor layer 2.

On the outer peripheral surface of the island-shaped portion 3 of the n-type semiconductor layer 2 and on a region where the island-shaped portion 3 of the n-type semiconductor layer 2 is not formed, a current blocking metal electrode 6 forms an insulating film 7. Are arranged through. In this case, the anode metal electrode 4 is made of a metal having a relatively small work function, for example, titanium. Further, the current blocking metal electrode 6 is made of the same material as the anode metal electrode 4 because it is desirable in terms of manufacturing that it is the same as the anode metal electrode 4.

The above is the configuration of the conventionally proposed Schottky junction diode. According to the conventional Schottky junction diode D having such a configuration, the anode metal electrode 4 is represented by a binary value of "1" (the positive electrode based on the negative terminal between the positive terminal and the negative terminal). N) for a cathode connected to a positive terminal of a signal source that obtains a signal having a voltage of “0” (zero or negative voltage based on the negative terminal between the positive terminal and the negative terminal). Type low resistance semiconductor substrate 1
Is connected to the other end of the load, one end of which is connected to the negative end of the signal source, so that the signal source is connected to the load via the Schottky junction diode shown in FIG. If the positive terminal is connected to the current blocking metal electrode 6, when the signal obtained from the signal source takes "1" in binary display, the signal shown in FIG.
7 is turned on by applying a forward voltage to both ends of the Schottky junction diode shown in FIG. 7, and in this case, a positive potential is applied to the current blocking metal electrode 6. Therefore, since the depletion layer hardly spreads from the insulating film 7 to the island-shaped portion 2, a current can be supplied to the load via the Schottky diode shown in FIG.

When the signal obtained from the signal source takes "0" in binary notation, a zero or reverse voltage is applied to both ends of the Schottky junction diode shown in FIG. The Schottky junction diode is turned off, and in this case, a zero or negative potential is applied to the current blocking metal electrode 6, so that the depletion layer extends to the island 3.

In the case of the conventional Schottky junction diode shown in FIG. 7, the metal electrode 4 for the anode is made of a metal having a relatively small work function. Current can be supplied to the load with a voltage that is hardly reduced from the voltage of the signal from the signal source.

[0008]

In the case of the conventional Schottky junction diode shown in FIG.
However, for the reasons described above, it is desirable that the anode metal electrode 4 be made of the same material, that it is made of a metal having the same work function as the anode metal electrode 4, and that a current is supplied to the load through the Schottky junction diode. It is desirable to widen the cross-sectional area of the island-shaped portion 3 in order to make a large amount of flow, so if the cross-sectional area of the island-shaped portion 3 is widened in such a manner, the signal from the signal source is displayed in a binary display. When “0” is taken, the depletion layer extending from the insulating film 7 to the island 3 does not expand enough to cross the island 3, so that the signal from the signal source is expressed as “0” in binary. , The load has a drawback in that a non-negligible leakage current flows to the load, which involves power consumption.

Thus, the present invention is free of the above-mentioned disadvantages,
It is intended to propose a new Schottky junction diode.

[0010]

A Schottky junction diode according to the present invention has an n-type low resistance semiconductor substrate for a cathode and an n-type cathode for the cathode, similarly to the conventional Schottky junction diode described above with reference to FIG. An n-type semiconductor layer formed on the low-resistance semiconductor substrate and forming an island on the side opposite to the cathode n-type low-resistance semiconductor substrate, and an island of the n-type semiconductor layer A metal electrode for an anode is formed on the surface opposite to the n-type low-resistance semiconductor substrate for a cathode so as to form a Schottky junction with the island-shaped portion; On the outer peripheral surface of the island portion, a current blocking metal electrode is disposed via an insulating film.

However, in the Schottky junction diode according to the present invention, in the Schottky junction diode having such a configuration, the anode metal electrode is
The current blocking metal electrode is made of a metal having a relatively small work function, and the current blocking metal electrode is made of a metal having a large work function as compared with the anode metal electrode.

In this case, the metal electrode for the anode may be made of titanium, and the metal electrode for current blocking may be made of platinum, molybdenum, tungsten, cobalt, titanium nitride or boron-doped polycrystalline silicon.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a Schottky junction diode according to the present invention will be described with reference to FIG. 1, the same reference numerals are given to portions corresponding to FIG. 7, and the detailed description is omitted.

The Schottky junction diode according to the present invention shown in FIG. 1 has the same current as that of the conventional Schottky diode shown in FIG. The blocking metal electrode 6 is a current blocking metal electrode 1 made of a metal having a larger work function than the anode metal electrode 4, such as platinum, molybdenum, tungsten, cobalt, titanium nitride or boron-added polycrystalline silicon.
6 and the current blocking metal electrode 16 extends to the top surface of the island portion 3 together with the insulating film 7, and the current blocking metal electrode 16 and the insulating film 7 pass through the island portion. A window 8 is made to expose the top of 3 to the outside,
7 except that the anode metal electrode 4 is formed on the current blocking metal electrode 16 through the window 8 so as to form a Schottky junction 5 with the island 3. It has the same configuration as a key junction diode.

The above is the configuration of the embodiment of the Schottky junction diode according to the present invention. The embodiment of the Schottky junction diode according to the present invention having such a configuration can be easily manufactured by taking the following sequential steps with reference to FIGS.

That is, an n-type semiconductor layer 2 'to be the n-type semiconductor layer 2 described later with reference to FIG. 1 is formed on a cathode n-type low-resistance semiconductor substrate 1 prepared in advance (FIG. 2A).
Next, a mask layer made of, for example, silicon oxide having the same plane pattern as the island-shaped portion 3 is formed on the n-type semiconductor layer 2, and then an etching process using the mask layer for the n-type semiconductor layer 2 as a mask is performed. , N-type semiconductor layer 2 as shown in FIG.
Then, the above-mentioned island-shaped portion 3 is formed, and then the mask layer is removed (FIG. 3B). Next, the island-shaped portion 3 is formed on the surface of the n-type semiconductor layer 2.
An insulating film 7 made of a silicon oxide film including the top surface and the outer peripheral surface is formed by a thermal oxidation process (FIG. 3C).

Next, a current blocking metal electrode 16 is formed on the silicon oxide film 7 by, for example, an electron beam evaporation method (FIG. 4D). Next, a window 8 is formed through the current blocking metal electrode 16 and the insulating film 7 so that the top surface of the island portion 3 is exposed to the outside (FIG. 4E).

Next, the anode metal electrode 4 which is attached to the island-shaped portion 3 in the window 8 so as to form a Schottky junction and is connected and extended on the current blocking metal electrode 16 is
It is formed by a deposition process using an electron beam evaporation method and a patterning process for the deposition process (FIG. 5A).

The above is the embodiment of the method of manufacturing the Schottky junction diode according to the present invention shown in FIG. As described above, the configuration of the Schottky junction diode according to the present invention shown in FIG. 1 has become more apparent.

According to the Schottky junction diode according to the present invention having such a configuration, the anode metal electrode 4 is displayed in binary in accordance with the description of the conventional Schottky junction diode shown in FIG. "1" (a positive voltage between the positive and negative ends with respect to the negative end) and "0" (a zero or negative voltage between the positive and negative ends with reference to the negative end) Voltage) is connected to the positive terminal of a signal source from which a signal having a voltage
Is connected to the other end of the load, one end of which is connected to the negative end of the signal source, so that the signal source is connected to the load via the Schottky junction diode shown in FIG. If the positive terminal is connected to the current blocking metal electrode 16 (however, in this example, since the current blocking metal electrode 16 is connected to the anode metal electrode 4, it is separately connected to the positive terminal of the signal source). Not necessary), the signal obtained from the signal source is 2
When the value is "1", the forward voltage is applied to both ends of the Schottky junction diode shown in FIG. 1 to turn on the Schottky junction diode shown in FIG. 1, and in this case, Current blocking metal electrode 16
Since a positive potential is applied to the gate electrode, the depletion layer hardly spreads from the insulating film 7 to the island-shaped portion 2, so that a current can be supplied to the load via the Schottky junction diode shown in FIG.

When the signal obtained from the signal source takes "0" in binary notation, both ends of the Schottky junction diode shown in FIG. Since a zero or reverse voltage is applied, the Schottky diode shown in FIG. 7 is turned off, and in this case, the current blocking metal electrode 6 is turned off.
Is applied with zero or negative potential, so that the depletion layer spreads over the island-shaped portion 3.

Also, in the case of the Schottky junction diode shown in FIG. 1, the metal electrode for anode 4 has a relatively small work function in accordance with the description of the case of the conventional Schottky junction diode shown in FIG. Metal
When the current is supplied to the load, the forward voltage drop at the anode metal electrode 4 is low, so that the current can be supplied to the load with a voltage that hardly drops from the voltage of the signal from the signal source. it can.

Further, in the case of the Schottky junction diode shown in FIG. 1, the current blocking metal electrode 16 is made of a metal having a larger work function than the anode metal electrode 4, so that a large amount of load is applied to the load through the Schottky junction diode. Even if the cross-sectional area of the island-shaped portion 3 is widened to allow the current to flow, when the signal from the signal source takes "0" in binary display, the depletion layer extending from the insulating film 7 side to the island-shaped portion 3 is reduced. It can be widened enough to cross the islands 3, so that when the signal from the signal source takes "0" in binary display, unnecessary leakage current flows to the Schottky junction diode and the load. There is no draining and unnecessary power consumption.

In the above description, only one embodiment of the present invention is shown.
6, and a metal electrode 6 for blocking current of the conventional Schottky junction diode shown in FIG.
Also, like the insulating film 7, it can be formed as not extending on the top surface of the island-shaped portion 3, and other various modifications and changes can be made without departing from the spirit of the present invention. .

[0025]

According to the Schottky junction diode of the present invention, when the signal source is connected to the load via the diode and the current blocking metal electrode is connected to the positive terminal of the signal source, When not controlled by a signal from a signal source, it does not cause unnecessary leakage current to flow through a Schottky junction diode and a load, and when controlled by a signal from a signal source,
There is no unnecessary power consumption associated with the Schottky junction diode and load.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a Schottky junction diode according to the present invention.

FIG. 2 is a schematic diagram showing a method of manufacturing the Schottky junction diode according to the present invention shown in FIG. 1 in sequential steps.

FIG. 3 is a schematic diagram showing a method of manufacturing the Schottky junction diode according to the present invention shown in FIG. 1 in a sequential step following the sequential step shown in FIG. 2;

FIG. 4 is a schematic diagram showing a method of manufacturing the Schottky junction diode according to the present invention shown in FIG. 1 in a sequential step following the sequential step shown in FIG. 3;

FIG. 5 is a schematic diagram showing a method of manufacturing the Schottky junction diode according to the present invention shown in FIG. 1 in a sequential step following the sequential step shown in FIG. 4;

FIG. 6 is a schematic diagram showing another embodiment of a Schottky junction diode according to the present invention.

FIG. 7 is a schematic diagram illustrating a conventional Schottky junction diode.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 n-type low-resistance semiconductor substrate for cathode 2 n-type semiconductor layer 3 island-shaped portion 4 metal electrode for anode 5 Schottky junction 6 metal electrode for current blocking 7 insulating film 8 window 16 metal electrode for current blocking

Claims (2)

[Claims] 1. An n-type low-resistance semiconductor substrate for a cathode, and an island formed on the n-type low-resistance semiconductor substrate for the cathode and opposite to the n-type low-resistance semiconductor substrate for the cathode. An anode-type metal electrode on the surface of the island portion of the n-type semiconductor layer opposite to the n-type low-resistance semiconductor substrate side for the cathode. And a Schottky junction diode in which a current blocking metal electrode is arranged via an insulating film on the outer peripheral surface of the island portion of the n-type semiconductor layer. Wherein the metal electrode for an anode is made of a metal having a relatively small work function, and the metal electrode for a current blocking is made of a metal having a large work function as compared with the metal electrode for an anode. Key junction diode . 2. The Schottky junction diode according to claim 1, wherein said anode metal electrode is made of titanium, and said current blocking metal electrode is made of platinum, molybdenum, tungsten, cobalt, titanium nitride, or boron-doped polycrystal. A Schottky junction diode made of silicon.