Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Low workfunction layer for electron emission
Reexamination Certificate
2001-01-04
2002-08-27
Ho, Hoai (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Low workfunction layer for electron emission
Reexamination Certificate
active
06441390
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron discharging apparatus and a method of manufacturing the apparatus. More particularly, the present invention relates to an electron discharging apparatus which may be employed for a display apparatus or an image-pickup apparatus, and, also applicable to such an electron beam exposure apparatus and an electron microscope as well.
2. Description of the Related Art
As was disclosed in the U.S. Pat. No. 4,303,930 (based on the Japanese Patent Laid-Open Publication No. SHOWA-56-15529/1981 and the other Japanese Patent Laid-Open Publication No. HEISEI-1-45694/1989) for example, in such a semiconductor apparatus substantially constituting a cold cathode, inverse-directional bias is applied so that avalanche multiplication of charged carrier can be attained. In this case, a certain electron can gain a thermal energy exceeding work function of electrons. In such a semiconductor apparatus, discharge of these electrons is easily executed by way of providing an accelerating electrode or a gate electrode on an insulating film formed on the main surface of the semiconductor apparatus. An aperture portion is formed at a position of an electron-discharging area of this insulating film. Discharge of electrons is more easily executed by providing a certain material capable of lowering work function of electrons on the surface of a semiconductor apparatus at the position of the electron discharging area.
Referring to a schematic cross-sectional view shown in
FIG. 9
, an example of a conventional electron discharging apparatus is described below.
As shown in
FIG. 9
, a conventional semiconductor substrate
110
is formed with a p+ type silicon substrate
111
and a p-type epitaxial layer
112
formed thereon. A p+ area
113
is formed in the p-type epitaxial layer
112
, and, an n++ area
114
is formed on an upper layer whereby forming a pn-junction
115
. Further, an n+ area
116
linked with the n++ area
114
is formed on an upper layer of the p-type epitaxial layer
112
. An insulating film
121
is formed on the above-referred semiconductor substrate
110
, and, an accelerating electrode
131
is formed on the insulating film
121
. Further, an insulating film
141
is formed by covering the accelerating electrode
131
.
Further, a connecting hole
122
connecting to the n+ area
113
is formed through the insulating film
121
. An extraction electrode
132
connecting to the n+ area via the connecting hole
122
is formed. Further, another connecting hole
142
connecting to the accelerating electrode
131
is formed through the insulating film
141
. Further, another extraction electrode
132
connecting to the accelerating electrode
131
is formed through the insulating film
141
, and another extraction electrode
133
connecting to the accelerating electrode
131
is formed through the connecting hole
142
. Further, a protecting film
143
is formed by covering the accelerating electrode
131
and the extraction electrodes
132
and
133
.
Further, an aperture portion
125
for discharging electrons is formed through the protection film
143
, the insulating film
141
, the accelerating electrode
131
, and the insulating film
121
. Further, another aperture portion
144
for wire-bonding is formed through the protecting film
143
on the extraction electrode
133
.
SUMMARY OF THE INVENTION
In order to maximize function of an electronic tube with emitted electrons by applying a voltage to the accelerating electrode utilized for a conventional electron discharging apparatus, structural relationship between an electron discharging surface and the accelerating electrode must be considered. However, in a conventional electron discharging apparatus based on a cold cathode structure, a pn-junction being the basis of the cold cathode structure is formed on a surface of a silicon substrate and an insulating film is formed on the pn-junction with using a planer process. Accordingly, there is such a critical problem that electrons can not fully be accelerated because of a remote distance between the electron discharging portion and the accelerating electrode. Further, in such a conventional electron discharging apparatus based on the conventional cold cathode structure, structurally, because of insufficient exposed area size of the accelerating electrode with respect to the electron discharging portion consisting of a pn-junction, acceleration of the discharged electrons may not be fully accomplished.
In order to fully solve the above problems, the present invention provides a novel electron discharging apparatus and a method of manufacturing the electron discharging apparatus.
A first electron discharging apparatus according to the present invention comprises the following:
a pn-junction formed on the part of the surface of a semiconductor substrate;
an insulating film formed on said semiconductor substrate;
an aperture portion formed through said insulation film on said pn-junction; and
an accelerating electrode formed on said insulating film so as to surround the periphery of said aperture portion;
wherein said accelerating electrode is formed so as to project its inner edge portion into said aperture portion. In the first electron discharging apparatus according to the present invention, inasmuch as the above-referred accelerating electrode is formed by way of projecting its inner edge portion into the aperture portion area, a lateral surface and the bottom surface of the accelerating electrode facing the aperture portion respectively extended into the aperture portion area. Accordingly, the accelerating electrode is provided with a greater exposure area with respect to an electron discharging portion consisting of a pn-junction than that of such an accelerating electrode provided for any of conventional electron discharging apparatuses. Because of this, electrons discharged from the pn-junction are fully accelerated.
A second electron discharging apparatus according to the present invention comprises the following:
a pn-junction formed on the part of the surface of a semiconductor apparatus;
an insulating film formed on said semiconductor substrate;
an aperture portion formed through said insulation film on said pn-junction;
and an accelerating electrode formed on said insulating film so as to surround the periphery of said aperture portion;
wherein said accelerating electrode is formed into a substantially L-shaped configuration at a cross-sectional plane.
In the second electron discharging apparatus according to the present invention, inasmuch as the above-referred accelerating electrode is formed into a substantially L-shaped configuration at a cross-sectional plane, the substantially L-shaped vertical-wall portion of the accelerating electrode is formed facing the aperture portion area, and thus, exposure area of the accelerating electrode against an electron discharging portion consisting of a pn-junction becomes greater than that of such an accelerating electrode provided for any of conventional electron discharging apparatuses. Because of this, electrons discharged from the electron discharging portion consisting of a pn-junction are fully accelerated.
A third electron discharging apparatus according to the present invention comprises the following:
a pn-junction formed on the part of the front surface of a semiconductor substrate;
an insulating film formed on said semiconductor substrate;
an aperture formed through said insulating film on said pn-junction; and
an accelerating electrode formed on said insulating film so as to surround the periphery of said aperture portion;
wherein said accelerating electrode is formed into a substantially inverse L-shaped configuration at a cross-sectional plane.
In the third electron discharging apparatus according to the present invention, inasmuch as the accelerating electrode is formed into a substantially inverse L-shaped configuration, the accelerating electrode is provided with a greater exposure
Saotome Nobuyuki
Sato Jun-ichi
Ho Hoai
Hoang Quoc
Kananen, Esq. Ronald P.
Rader & Fishman & Grauer, PLLC
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