Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With heterojunction
Reexamination Certificate
2002-02-07
2004-11-30
Wille, Douglas (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With heterojunction
C257S103000
Reexamination Certificate
active
06825499
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a display system and a method of producing the same, and particularly to a display system in which an insulation layer with semiconductor light-emitting devices as light sources embedded therein is thinned and a conductor film is provided on upper end portions of the semiconductor light-emitting devices exposed by the thinning, whereby upper end portion electrodes are led out, and a method of producing the same.
As a method of leading out an electrode of a semiconductor device covered with an insulation layer to the exterior, a method of forming a contact hole in the insulation layer by lithography, embedding a conductor material in the contact hole by, for example, a sputtering method and forming a conductor film on the surface of the insulation layer is widely conducted.
FIG. 17
shows a process of leading out an electrode
51
in a semiconductor device
50
.
FIG. 17A
is a sectional view showing a silicon substrate
52
provided with the electrode
51
and a SiO
2
insulation layer
53
provided on the surface thereof. In order to lead out the electrode
51
to the upper side of the insulation layer
53
, a contact hole
54
is formed at the location where the electrode
51
is present, as shown in FIG.
17
B. At this time, a positional deviation may occur between the contact hole
54
and the electrode
51
. Furthermore, the probability of a positional deviation is greater as the electrode
51
is made smaller.
In order to fill the contact hole
54
with a conductor metal and provide a lead-out electrode on the upper surface of the insulation layer
53
, sputtering or vapor deposition of a conductor metal
55
such as aluminum is carried out. However, the straight flying characteristics of the conductor metal particles, the conductor metal
55
tends to be deposited on a bottom portion of the contact hole
54
, but not on the side wall, because the side wall is hidden by the conductor metal
55
which is deposited and grown on the inner peripheral portion of the top opening of the contact hole
54
, as shown in FIG.
17
C. As the process proceeds, connection failure may occur at the side wall portion of the contact hole
54
. Alternatively, there may be difficulty in closing the opening at the top of the contact hole while leaving cavity on the inside of the contact hole
54
, as shown in FIG.
17
D.
In order to facilitate the connection described above, a method is known in the prior art in which the insulation layer is etched back. Namely, in Japanese Patent Laid-open No. Hei 7-142579, a contact wiring is adopted in place of the contact hole.
FIG. 18
shows a process of connecting a lower layer wiring and an upper layer wiring by a contact wiring in the case of producing an image display system including surface conduction type electron emitting devices (SCE) as elements. As shown in
FIG. 18A
, a metal is electron beam vapor deposited on the lower layer wiring
62
provided on an insulating substrate
61
, and unrequired portions are lifted up to form the contact wiring
63
. Subsequently, as shown in
FIG. 18B
, an insulation film
64
of silicon oxide or the like is formed over the entire surface by a sputtering method. Further, as shown in
FIG. 18C
, a photoresist
65
is formed over the entire surface. Thereafter, as shown in
FIG. 18D
, etching back for flattening is conducted to expose the surface of the contact wiring
63
, and, as shown in
FIG. 18E
, an upper layer wiring
66
is provided. Thus, a multilayer wiring is disclosed. However, this method exposes the contact wiring, not the semiconductor light-emitting devices.
Japanese Patent Laid-open No. Hei 7-94124 discloses a method of producing light-emitting devices in a display system including electric field emission cathodes. As shown in
FIG. 19A
, a cathode chip
70
a
is provided on a main surface of a substrate
70
, and, as shown in
FIG. 19B
, an insulation layer
72
and an anode layer
73
are sequentially provided on the substrate
70
by sputtering. Further, as shown in
FIG. 19C
, a fluorescent material layer
74
is provided by sputtering. Then, as shown in
FIG. 19D
, a polyimide resin layer
75
is deposited to cause flattening, and thereafter, the polyimide resin layer
75
is etched back to expose a protuberant portion of the fluorescent material layer
74
, leaving the polyimide resin layer
75
therearound. Then, as shown in
FIG. 19E
, the fluorescent material layer
74
, the anode layer
73
and the insulation layer
72
are sequentially selectively etched using the polyimide resin layer
75
as a mask, whereby the cathode chip
70
a
is exposed. However, this method has the exposure of the cathode chip itself as an object, and is not for leading out the upper end portion electrode of the semiconductor light-emitting device exposed.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above described limitations of the prior art. Accordingly, it is an object of the present invention to provide a display system including semiconductor light-emitting devices disposed on and fitted to a substrate surface and covered with an insulation layer, in which upper end portion electrodes of the semiconductor light-emitting devices are led out easily and securely. The invention further includes a method of producing the same.
The above-mentioned problems can be solved by a first aspect or a second aspect of the present invention. The inventive solutions will be described below.
In accordance with a first aspect of the present invention, there is provided a display system including multiple semiconductor light-emitting devices disposed on and fitted to a substrate surface. An insulation layer with the semiconductor light-emitting devices embedded therein is thinned selectively or non-selectively. Further, a conductor film is provided on upper end portions of the semiconductor light-emitting devices which are exposed by the thinning, and upper end portion electrodes of the semiconductor light-emitting devices are led out to an upper surface of the insulation layer. Unlike display systems in which a contact hole for leading out the upper end portion electrode onto the insulation layer is not provided, the display system of the present invention is free of the positional deviation problems between the contact hole and the upper end portion electrode and contact failure in the contact hole. Thus, the upper end portion electrodes of the semiconductor light-emitting devices are connected easily and securely.
Preferably, there is provided a display system in which the insulation layer is formed of a high polymeric compound capable of forming a coating film containing a polyimide resin, an epoxy resin or a synthetic rubber or a glass capable of forming a coating film. In such a display system, the insulation layer is formed by application, so that the insulation layer can be easily formed even in the case where the area of the substrate surface is large, and the display system is reduced in cost.
Preferably, there is provided a display system in which the insulation layer is composed of silicon oxide or silicon nitride formed by a CVD (chemical vapor deposition) method or a sputtering method. Such a display system shows excellent heat resistance owing to the insulation layer composed of the inorganic material.
Preferably, there is provided a display system in which the thinning of the insulation layer is carried out by a dry etching method under an oxygen plasma atmosphere, a chemical mechanical polishing method or a combination of both methods. In such a display system, a most appropriate method is selected according to the kind of material of the insulation layer adopted and the conditions of the thinning.
Preferably, there is provided a display system in which the semiconductor light-emitting device has a primary light-emitting direction in a direction from a light-emitting region toward a lower end surface on the substrate surface, and has a reflective surface for downward reflection at a portion above the lig
Doi Masato
Nakajima Hideharu
Bell Boyd & Lloyd LLC
Wille Douglas
LandOfFree
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