Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1999-07-20
2001-10-02
Ramsey, Kenneth J. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S309000
Reexamination Certificate
active
06297587
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a cold cathode field emission device, a cold cathode field emission display and processes for the production thereof. More specifically, it relates to a cold cathode field emission device having the form of a column, a flat panel type cold cathode field emission display having a plurality of the cold cathode field emission devices arranged in a two-dimensional matrix, and processes for the production thereof.
Studies are being made on various flat panel type displays for an image displaying unit which is to replace currently main-stream cathode ray tubes (CRT). The flat type displays include a liquid crystal display (LCD), an electroluminescence display (ELD) and a plasma display (PDP). Further, there is also proposed a cold cathode field emission display from the viewpoint of a brightness on displaying.
The above cold cathode field emission display (to be sometimes simply referred to as “field emission display” hereinafter) has a plurality of pixels as its conceptual view and is shown in
FIG. 33
, and each pixel comprises a plurality of Spindt type cold cathode field emission devices (to be sometimes simply referred to as “Spindt type field emission device” hereinafter) arranged in a two-dimensional matrix form. Each Spindt type field emission device comprises a patterned electrode layer (cathode electrode layer)
11
, an insulating interlayer
12
, a gate electrode
14
formed on the insulating interlayer
12
and an emitter electrode
102
formed in an opening portion formed in the insulating interlayer
12
.
For example, the cathode electrode layer
11
is formed on a dielectric supporting substrate
10
constituted of a glass substrate, and the cathode electrode layer
11
is composed, for example, of niobium (Nb). The cathode electrode layer
11
and the dielectric supporting substrate
10
are covered with the insulating interlayer
12
. The emitter electrode
102
is a conical tip which is formed on the cathode electrode layer
11
according to a semiconductor production process and has a diameter of approximately 1.0 &mgr;m. The emitter electrode
102
is composed of molybdenum (Mo) or the like. On the top end side of the emitter electrode
102
is provided the gate electrode
14
so as to surround the emitter electrode
102
. A voltage is applied between the emitter electrode
102
and the gate electrode
14
to generate an electric field, and due to the electric field, electrons are extracted from the top end of the emitter electrode
102
. The electrons are attracted to a second electrode layer (anode electrode layer)
21
formed on a transparent substrate
20
to collide with a fluorescent layer (light emitting layer)
22
formed between the anode electrode layer
21
and the transparent substrate
20
, and as a result, the fluorescent layer
22
emits light, and an intended image can be obtained. The performance of the Spindt type field emission device is controlled in principle on the basis of a voltage to be applied to the gate electrode
14
. Such a display is disclosed, for example, in U.S. Pat. No. 4,857,161. The process for the production of the Spindt type field emission device disclosed in the above U.S. Patent will be outlined with reference to
FIGS. 34A
,
34
B,
35
A and
35
B, hereinafter.
[Step-
10
]
A niobium layer is formed on a dielectric supporting substrate
10
constituted, for example, of a glass substrate, and then the niobium layer is patterned to form an electrode layer (cathode electrode layer)
11
. Then, an insulating interlayer
12
, for example, of SiO
2
is formed on the entire surface by a CVD method. Further, a gate electrode
14
is formed, for example, by forming a metal layer on the insulating interlayer
12
by a CVD method and then patterning the metal layer. Then, an opening portion
15
is formed in the gate electrode
14
by lithography and dry etching methods. Further, the insulating interlayer
12
below the opening portion
15
is etched to form an opening portion
13
in the insulating interlayer
12
(see FIG.
34
A).
[Step-
20
]
Then, a peeling-off layer
100
composed of aluminum is formed on the gate electrode
14
by oblique vapor deposition of aluminum (see FIG.
34
B). Aluminum is obliquely vapor-deposited such that sputtered particles of aluminum arrive onto the gate electrode
14
with an angle tilted at approximately 75° with regard to the normal of the gate electrode
14
. As a result, aluminum is deposited to form the peeling-off layer
100
having “eaves” extending from an edge portion
15
A of the opening portion
15
formed in the gate electrode
14
. As a result, the opening portion
15
is decreased in diameter by the peeling-off layer
100
.
[Step-
30
]
Then, a metal layer
101
is formed by vertical vapor deposition of molybdenum, whereby an emitter electrode
102
of molybdenum having a conical tip is formed in a bottom portion of the opening portion
13
(see FIG.
35
A).
[Step-
40
]
Then, the peeling-off layer
100
is peeled off from the surface of the gate electrode
14
by an electrochemical process and a wet process, to selectively remove the metal layer
101
on the gate electrode
14
(see FIG.
35
B), whereby a Spindt type field mission device having the structure shown in
FIG. 33
an be obtained.
In the Spindt type field emission device having the structure shown in
FIG. 35B
, the electron emitting characteristic thereof is greatly dependent upon a distance from the edge portion
15
A of the opening portion
15
formed in the gate electrode
14
to the top end portion of the emitter electrode
102
. And, the above distance is greatly dependent upon the process accuracy of the form of the opening portion
15
, upon the dimensional accuracy of the diameter of the opening portion
15
and upon the thickness accuracy of the metal layer
101
formed in [Step-
30
]. It is therefore required to carry out the formation of the metal layer
101
uniformly all over the entire surface of the dielectric supporting substrate for producing the field emission display having a plurality of Spindt type field emission devices having uniform characteristics. Further, if the metal layer
101
cannot be vertically deposited, the distance from the top end portion of the conical emitter electrode
102
to the gate electrode
14
varies among Spindt type field emission devices. As a result, the image displaying characteristics of the field emission display, such as brightness of an image, vary. However, it is very difficult to vertically deposit the metal layer
101
having a uniform thickness all over the entire surface of a large-area dielectric supporting substrate for producing a large-area field emission display, and not only an in-plane variation of thickness of the metal layer
101
on the dielectric supporting substrate but also a variation of thickness among lots are also liable to occur. Moreover, a large-scale deposition apparatus is required. Further, since it is required to deposit the metal layer
101
having a thickness of approximately 1 &mgr;m or more by a vapor deposition method, the throughput is low.
Furthermore, it is required to form the peeling-off layer
100
by an oblique vapor deposition method. However, it is difficult to accurately form the above peeling-off layer
100
all over the entire surface of the dielectric supporting substrate having a large area, and it is also difficult to accurately deposit the peeling-off layer
100
such that the peeling-off layer
100
extends from the edge portion
15
A of the opening portion
15
formed in the gate electrode
14
so as to have “eaves”. Further, the formation of the peeling-off layer
100
varies not only in the in-plane of the dielectric supporting substrate but also among lots.
Furthermore, not only it is very difficult to peel off the peeling-off layer
100
all through the entire surface of the glass substrate having a large area for producing the field emission display having a large area, but a
Kikuchi Kazuo
Kubota Shinji
Kananen Ronald P.
Rader Fishman & Grauer
Ramsey Kenneth J.
Sony Corporation
LandOfFree
Color cathode field emission device, cold cathode field... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Color cathode field emission device, cold cathode field..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Color cathode field emission device, cold cathode field... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2573421