JPH03129631A - Electron emission element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of use on a-beam] The present invention relates to an electron-emitting device, and particularly to an electron-emitting device using avalanche amplification.

[Prior Art] Conventionally, as an electron-emitting device using avalanche amplification, for example, US Pat. No. 4,259,678 and US Pat.
As described in No. 30, a p-type semiconductor layer and an n-type semiconductor layer are joined to form a diode structure, and a reverse bias voltage is applied to both ends of this diode to cause avalanche amplification to hot the electrons. A device is known in which electrons are emitted from the surface of an n-type semiconductor layer to which cesium or the like is attached to lower the work function of the surface.

[Problem to be solved by the invention] However, the conventional electron-emitting device as described above has the following problems:
Because a pn junction diode structure is used, the switching characteristics of the device are numerically extremely slow compared to Schottky diodes, and therefore the upper limit of the frequency for direct modulation of the electron-emitting device is low. There was a problem in that the applications using the emitter were limited to a narrow range.

In addition, conventional electron-emitting devices such as those mentioned above have a guard ring structure around the electron-emitting part, but since a large device area is required to form this guard ring structure, it is necessary to Another issue was that it was difficult to adapt.

Furthermore, in the conventional electron-emitting device as described above, the process steps for forming an n-type guard ring layer, a p-type cavity concentration layer, and an n-type surface layer on a p-type semiconductor layer are complicated, and in some cases, the process steps are extremely complicated. There is also the problem of low yields and therefore high manufacturing costs due to the technical difficulties in creating a thin injection layer.

The present invention was tried in view of the above-mentioned problems, and has excellent switching characteristics, easy miniaturization, and
The present invention is characterized by providing an electron-emitting device that can be manufactured at low cost.

[Means for Solving the Problems] The electron-emitting device of the present invention includes: a p-type semiconductor substrate; and a p-type semiconductor layer formed on the p-type semiconductor substrate and having an impurity concentration that causes electron avalanche breakdown. a Schottky electrode connected to the p-type semiconductor layer; means for applying a reverse bias voltage to the Schottky electrode and the p-type semiconductor layer to emit electrons from the Schottky electrode; and an extraction electrode for extracting emitted electrons to the outside.The electron-emitting device has an oxide film formed using a LOGOS method around the Schottky junction.

In the above feature, it is desirable that the p-type semiconductor substrate is made of Si.

In the above feature, it is preferable that the p-type semiconductor layer has a p-type heavily doped region, and that the highly doped region and the Schottky electrode are in contact with each other. At this time, the impurity concentration of the p-type heavily doped region is 2X1017 to 10x10 "cm-',
The impurity concentration of the region other than the p-type heavily doped region of the first conductivity type semiconductor layer is 2X1018 to 1O1.
It is desirable that it be 0X10111a'.

In the above feature, the thickness of the Schottky electrode is 0.
．． It is desirable that the thickness is 1 μm or less.

In the above feature, it is preferable that the Schottky electrode is formed by siliciding Gd by heat treatment or the like, and then depositing one atomic layer of Ba or Cs.

[Function] According to the present invention, by making the configuration of the electron-emitting device similar to that of a Schottky junction diode, delay in switching time due to accumulation of minority carriers is improved,
This makes it possible to increase the modulation frequency of direct modulation.

Further, in the present invention, in a Schottky type electron-emitting device, a LOCOS structure (local oxidation
Abbreviation of 5ilicon, Ph1lips Res,
Rep, 25, 1970゜pp, 118-132)
Since edge breakdown has been improved by separating the elements using , it is possible to eliminate the need for a guard ring configuration, making it possible to make the configuration of the electron-emitting device extremely simple and miniaturize it. becomes. Also,
MOLD structure (metal-overlap 1ate
Abbreviation for rally-diffused, 5olid-St
ate Electronics, 1977, vol.
20. pp.

496 to 506) to form a highly doped region, it becomes possible to further simplify the structure of the electron-emitting device and to miniaturize it.

Furthermore, by using Si as the semiconductor substrate, when forming an oxide film in the manufacturing process of electron-emitting devices as described later, it is possible to form an oxide film with a uniform thickness and excellent breakdown voltage. becomes.

In the present invention, the concentration of the heavily doped region is 2X
By setting fO'' to foxlo''cm-', the efficiency of electron emission can be maximized. This is because if the impurity concentration is higher than 10x1017 cm-', tunnel breakdown occurs without avalanche amplification, and if it is lower than 2XfO1 cm-', the electron generation efficiency decreases.

Further, in order to efficiently emit electrons, it is desirable that the thickness of the Schottky electrode be 0.1 μm or less.

If it is thicker than 0.1 μm, the generated electrons will collide with electrons in the metal and lose energy! This is because it becomes difficult to pass through the poles. However, if it is too thin, the resistance of the Schottky electrode will become so large that it cannot be ignored, making it impossible to efficiently supply voltage to the element, and the film will be destroyed by the flowing current, so the thickness should be around 0.02 μm. is the most desirable.

Furthermore, with the present invention, ion implantation into the Schottky junction forming area can be completed in one time, which greatly simplifies the process and reduces process problems such as reliability and device variations. be.

Next, the mechanism of electron emission will be explained.

The Schottky diode utilizes a Schottky barrier φBP formed at the junction between a p-type semiconductor and metal, as shown in the energy band diagram of FIG.

If we apply a reverse bias to this Schottky diode,
Avalanche amplification occurs, and in the electrons generated by the avalanche amplification, the work function φW of the Schottky metal
Electrons with energy greater than K pass through the metal and are emitted into the vacuum.

In order to realize such a mechanism, in the present invention,
The structure, concentration, and shape of the semiconductor have been optimized to prevent leakage at the edges during Schottky diode formation and to generate avalanche amplification at specific locations, making it possible to extract electrons extremely efficiently. became.

[Example] (Example 1) An embodiment of the present invention will be described with reference to the drawings.

FIG. 1(a) and FIG. 1(b) are schematic configuration diagrams of a semiconductor electron-emitting device according to this embodiment, and FIG.
) is a plan view, and FIG. 1(b) is a sectional view taken along the line A-A.

This example will be described below according to the manufacturing process.

■As shown in Figures 1(a) and 1(b), a p-type semiconductor substrate! (5i(100) was used in this example.)
The type semiconductor layer 2 was epitaxially grown by the CVD method, and then a thermal oxide film with a thickness of several hundred layers was formed.

■ By performing appropriate patterning using a photolithography process, the thermal oxide film on the part where the high concentration p-type semiconductor region 3 will be formed is opened, and B ions are injected to a depth of about 3000 Å and an impurity concentration of 2×10 17 to 1 oxlo” c.
It was injected so that it was m-'.

■A SiN film was formed using the CVD method, and etched with CF4 or the like so that 5iNi remained in the area where the element was to be formed.Furthermore, a field oxide film 4 was formed as the element pre-region 4 using an oxidation process ( LOCOS method).

Simultaneously with the formation of LOGO 3, the highly doped p-type semiconductor region 3 is activated and exposed by etching, after which the electrode 5 is formed to a thickness of 5000 mm and appropriate patterning is performed, and finally the electrode 5 is formed. It was placed in contact with the Schottky electrode.

(2) An insulating layer 6 was formed to a thickness of 1 μm by sputtering SiO, and an extraction electrode 7 was formed by evaporating Au to a thickness of 2000 Å.

(2) After patterning into an electrode shape using a lithography resist process, the electrode 7 was etched into an appropriate shape by C%Ar ion milling.

(2) The S i 02 layer 6 was buttered using hydrofluoric acid wet etching to expose the Schottky joint.

(2) Gd1li as the Schottky electrode 8 was EB-deposited to a thickness of about 150 mm, and heat treated at 350° C. for 5 minutes to form GdSi2, completing an electron-emitting device.

At this time, the barrier hide φBP was 0.7V, making it a good Schottky diode.

In the electron-emitting device manufactured in this way, when a reverse bias is applied to the p-type semiconductor layer 2, the Schottky electrode 8i8, and the electrode 5 by the power supply 12, the high concentration p-type semiconductor region 3 and the Schottky electrode 8 are Avalanche amplification occurs at the interface, and the generated hot electrons pass through the extremely thin Schottky electrode 8, seep into the vacuum region, and are emitted to the outside of the device by the electric field generated by the extraction electrode 7.

In the electron-emitting device according to this example, the device could be formed easily and accurately by using the LOCOS method as the device isolation method.

Furthermore, by providing a high concentration p region within the junction using a MOLD structure, it was possible to prevent non-uniform breakdown at the edge and form an extremely uniform and minute electron emitting region.

Furthermore, by using the MOLD structure, the pn junction guard ring that was conventionally necessary was removed, so the recovery time of the diode was extremely quick and good switching characteristics could be obtained.

Note that by depositing one atomic layer of an alkali metal such as Ba or Cs on the surface of the Schottky electrode 8, it is also possible to lower the work function of the surface and extract more electrons.

(Example 2) Hereinafter, a second example of the present invention will be described using FIG. 2.

In this example, the electron-emitting device of the present invention is configured to prevent crosstalk between the devices.

■First, an n-type semiconductor substrate (5L (100) in this example)
A layer 14 containing almost no impurities is formed on the surface) 15 by CVD.
It was cut to a thickness of 3 μm using the D method.

■Next, B is ion-implanted into the layer 14, which does not contain any impurities, to an impurity concentration of 1 to 5×10”cm−
', the p-type conductive layer 2 was formed by implanting to a depth of about 1 μm.

■Furthermore, the ohmic contact layer 13 is
It was formed by ion-implanting B to a thickness of cm' or more.

(2) Thereafter, an electron-emitting device was completed using substantially the same steps as in Example 1.

By applying a reverse bias to the p-type semiconductor ohmic electrode 10 and the electrode 5 to the electrode 8 and the electrode 5, the electron-emitting devices manufactured in this way can be controlled individually. We were able to.

(Example 3) Hereinafter, a third example of the present invention will be described using FIG. 4.

In this example, the semiconductor electron-emitting devices shown in Example 2 are arranged in the X direction and the Y direction to form a matrix.

In this example, in order to configure a color display, electron-emitting devices for R, G, and 83 colors are arranged in one pixel size, and the shape of the electron-emitting devices is designed to obtain as much light-emitting area as possible. Constructed in a rectangular shape.

The manufacturing process was almost the same as in Example 2 described above.

In the electron-emitting device of this example, (R1,
Gl, Bl, R2, G2. By applying a reverse bias between any one point in B2) and any one point in (a, b) in the Y direction, electrons can be emitted from any one point in the matrix electron-emitting device. Can be done.

[Effects of the Invention] As explained above, in a Schottky type semiconductor electron-emitting device, by using the LOCOS method around the Schottky junction, the pn junction guard ring is removed and the switching recovery time is almost eliminated. This makes it possible to achieve extremely high modulation speeds and widen the range of applications for electron-emitting devices. Furthermore, since element isolation and edge protection can be performed at the same time, it is possible to miniaturize the elements, and further simplifies the process.

In addition, by forming a p-type conductive layer with a high concentration locally, it is possible to generate uniform avalanche amplification at the injection part, making it possible to obtain a highly uniform and minute spot electron beam. became.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing a semiconductor electron-emitting device according to a first embodiment of the present invention, and FIG. 1(b) is an A-A of the semiconductor electron-emitting device shown in FIG. 1(a). FIG. 2 is a schematic cross-sectional view showing an electron-emitting device according to a second embodiment of the present invention; FIG. 3 is a schematic cross-sectional view showing an electron-emitting device according to a second embodiment of the present invention; FIG. The energy band diagram, Figure 4, is the third embodiment of the present invention.
5 is a schematic cross-sectional view taken along the AA cross section of the semiconductor electron-emitting device shown in FIG. 4; FIG. 6 is a schematic top view showing the electron-emitting device according to the example of FIG. FIG. 2 is a schematic cross-sectional view taken along the B-8 cross section of a semiconductor electron-emitting device. (Explanation of symbols) 1...Substrate, 2...p-type semiconductor layer, 13.3...
High concentration p-type semiconductor layer, 4... 11 regions for elements, 5...
・Schottky contact electrode, 6...insulating layer,
7... Bow opening electrode, 8... Schottky electrode, 9
...Depletion layer, 10...Ohmic electrode, 11, 12
...Power source, 14...Epitaxial growth layer. Figure (A) Figure (B) 0 Figure 2 Figure Figure

Claims (6)

[Claims] (1) a p-type semiconductor substrate; a p-type semiconductor layer formed on the p-type semiconductor substrate and having an impurity concentration that causes electron avalanche breakdown; a Schottky electrode bonded to the p-type semiconductor layer and; the Schottky electrode and the p
An electron-emitting device comprising: means for applying a reverse bias voltage to a Schottky type semiconductor layer to emit electrons from the Schottky electrode; and an extraction electrode for extracting the emitted electrons to the outside. An electron-emitting device comprising an oxide film formed using a LOCOS method around the Schottky junction. (2) The electron-emitting device according to claim 1, wherein the p-type semiconductor substrate is made of Si. (3) Claim 1 or 2, wherein the p-type semiconductor layer has a p-type heavily doped region, and the highly doped region and the Schottky electrode are in contact with each other.
The electron-emitting device described above. (4) The impurity concentration of the p-type heavily doped region is 2×10^1^7cm^-^3 to 10×10^1^7c
m^-^3, and the p of the first conductivity type semiconductor layer
The impurity concentration in the region other than the heavily doped region of the mold is 2.
4. The electron-emitting device according to claim 3, wherein the electron emitting device has a diameter of x10^1^6 to 10 x 10^1^6 cm^-^3. (5) The electron-emitting device according to any one of claims 1 to 4, wherein the Schottky electrode has a thickness of 0.1 μm or less. (6) The electron-emitting device according to any one of claims 1 to 5, wherein the Schottky electrode is formed by siliciding Gd by heat treatment or the like and then depositing one atomic layer of Ba or Cs.