Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-11-22
2004-09-21
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S137000, C349S138000
Reexamination Certificate
active
06795144
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection type liquid crystal display device in which a switching device and a reflector are formed on a semiconductor substrate, and a liquid crystal is sealed between the semiconductor substrate and a canmo electrode, a module for use in the reflection type liquid crystal display device, and a method of manufacturing the same.
2. Description of the Prior Art
As a head mount display and a projection type display, a reflection type liquid crystal display device which is called a silicon chip-based liquid crystal has recently been paid attention to.
FIG. 1
is a schematic view showing a principle of a reflection type liquid crystal display device using the silicon chip-based liquid crystal, and
FIG. 2
is an assembly view showing a constitution of the same reflection type liquid crystal display device.
The reflection type liquid crystal display device is constituted of a light source
51
composed of red-, green-, and blue-color light emitting diodes; a polarizer
52
; an analyzer
53
; and a liquid crystal on silicon (hereinafter referred to as a LCOS) unit
54
.
The LCOS unit
54
is constituted of a plurality of miniaturized reflectors (electrode)
61
arranged in a matrix fashion; a silicon chip module
54
a
in which devices such as CMOSs (not shown) are formed; and a liquid crystal panel
54
b
located on the silicon chip module
54
a
. Furthermore, the liquid crystal panel
54
b
is composed of a sealing member
66
; a glass substrate
67
; and a liquid crystal layer
68
sealed therebetween. A common electrode
67
a
made of a transparent electrically- conductive material is formed on a lower surface of the glass substrate
67
.
FIG. 3
is a schematic plan view of the silicon chip module
54
a
. As shown in
FIG. 3
, a number of miniaturized reflectors
61
formed of aluminum alloy are arranged in the silicon chip module
54
a
in a matrix fashion. A MOS transistor (switching device)
62
is formed in each of the reflectors
61
. Gate electrodes of the MOS transistors
62
arranged in the lateral direction are connected to the same gate bus line
73
b
, and the drains of the MOS transistors
62
arranged in the longitudinal direction are connected to the same data bus line
76
b
. Furthermore, the source of each MOS transistor
62
is connected to corresponding one of the reflectors
61
.
FIG. 4
is a section view of the silicon chip module
54
a
. A MOS transistor constituted of a gate electrode
73
a
, a source
72
a
and a drain
72
b
is formed on a silicon substrate
71
. Note that the gate bus line
73
b
shown in
FIG. 3
is formed in the same wiring layer as that of the gate electrode
73
a.
An interlayer insulating film
74
is formed on the silicon substrate
71
, and an intermediate wiring
76
a
and the data bus line
76
b
are formed on this interlayer insulating film
74
. A plurality of connecting plugs
75
a
are buried in the interlayer insulating film
74
, and the intermediate wiring
76
a
is connected to the source
72
a
of the MOS transistor via the connecting plugs
75
a
. The data bus line
76
b
is connected to the drain
72
b
of the MOS transistor.
An interlayer insulating film
77
is formed on the intermediate wiring
76
a
and the data bus line
76
b
. Moreover, the reflectors
61
are formed on the interlayer insulating film
77
. A plurality of connecting plugs
78
a
are buried in the interlayer insulating film
77
, and the reflector
61
is electrically connected to the source
72
a
of the MOS transistor via the connecting plug
78
a
, the intermediate wiring
76
a
and the connecting plug
75
a.
In the reflection type liquid crystal display device constituted in the above described manner, a beam of light emitted from the light source
51
is made to be uniform in its oscillation direction when the beam of light passes through the polarizer
52
, as shown in FIG.
1
. The polarized light that has passed through the polarizer
52
travels through the liquid crystal panel
54
b
of the LCOS unit
54
, and reaches the reflector
61
. The reflected light by the reflector
61
passes through the liquid crystal panel
54
b
again, and then tends to the analyzer
53
. For example, in the case where the liquid crystal panel
54
b
is a TN (Twisted Nematic) mode, the oscillation direction of the light is twisted by a fixed angle while the light travels from the reflector
61
to the liquid crystal panel
54
b
in a state where no voltage is applied between the reflector
61
and the common electrode
67
a
. On the other hand, when a sufficiently high voltage is applied between the reflector
61
and the common electrode
67
a
, the oscillation direction of the light hardly change while the light travels from the reflector
61
to the liquid crystal panel
54
b
. For this reason, when the polarizer
52
and the analyzer
53
are disposed so that the light is shield with no application of a voltage, the light comes to transmit therethrough with an application of the voltage. By controlling the application voltage for each reflector
61
, a desired image is displayed.
Incidentally, in the case of the reflection type liquid crystal display device having the above-described structure, it is important that a surface of the reflector
61
is flat. Therefore, before the reflector
61
is formed, a surface of the interlayer insulating film
77
is polished to be flat by use of, for example, a CNP (Chemical Mechanical Polishing) before the reflector
61
is formed.
However, the inventors of this application of the present invention consider that there are the problems described below in the foregoing conventional reflection type liquid crystal display device. To be specific, the surface of the silicon chip module
54
a
has irregularities equivalent to a thickness of the reflector
61
. Therefore, if air enters gaps between the reflectors
61
, a dielectric constant varies, and this causes a poor color tone and the like. In order to prevent such drawback, it is conceived that after the reflector is formed, an insulating material is buried in gaps between the reflectors by use of a method to coat SOG (Spin On Glass), to deposit a plasma oxide film or the like. However, the insulating substance such as SOG is attached onto the reflector, variations of gaps between the reflector and the liquid crystal are brought about, thus causing a poor color tone.
Although removal of the insulating substance attached onto the reflector by etching is also conceived, the surface of the reflector is corroded during etching of the insulating substance, and hence a reflection efficiency of the light is lowered.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a reflection type liquid crystal display device which has a good display quality, a module for use in the reflection type liquid crystal display device and a method of manufacturing the same by burying an insulating substance in gaps between its reflectors and flattening a surface of its semiconductor chip module.
The module for use in the reflection type liquid crystal display device of the present invention comprises a plurality of switching elements formed on a semiconductor substrate, a first insulating film formed on the semiconductor substrate, a plurality of reflectors formed on the insulating film, each of which is electrically connected to corresponding one of switching elements via corresponding one of connecting plugs buried in the insulating film, and a second insulating film buried in a gap between the reflectors, the second insulating film securing flatness of a surface of the reflector.
In the present invention, the second insulating film is buried in the gap between the reflectors, and the second insulating film secures the flatness of the surface of the module. With such structure, a good display characteristic can be obtained.
A method of manufacturing the module for use in the reflection type liquid crystal display device of the present invention comprises: a switching elements fo
Ohashi Makoto
Okuda Shoji
Greer Burns & Crain Ltd.
Nguyen Hoan
Ton Toan
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