JPH0968718A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody a reflection type liquid crystal display device having the flat reflection surface of a pixel electrode laminated panel. SOLUTION: This reflection type liquid crystal display device is constituted by consisting the panel of a silicon substrate 1, a glass substrate 6 and liquid crystals 9 between these substrates and forming transistors(TRs) 10, 20 arranged in a matrix form on this silicon substrate 1 and pixel electrodes 34D arranged in a matrix form above these TRs. The reflection type liquid crystal display device described above has multilayered wiring layers 31, 32, 33 which are disposed between the layers of the TRs 10, etc., and the layers of the pixel electrodes 34D and connect the layers corresponding to each other. At least the pixel arranging parts of these wiring layers 31, etc., consist of wiring pattern parts 31S, 31D, 32D, 33D and residual pattern parts 31F, 31F, 33F, etc., formed integrally therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device, and more particularly to a reflection type liquid crystal display device having a reflection panel suitable for a so-called projector or the like, that is, a liquid crystal display panel having a fine reflection characteristic.

[0002]

2. Description of the Related Art Conventionally, as a reflection type liquid crystal display device, for example, one described in JP-A-4-56827 is known. This is shown in FIG. 4 which is a cross section of the panel.
It is equipped with a reflection panel encapsulating. On the surface of the silicon substrate 1 on the liquid crystal 9 side, MosFETs 2 arranged in a matrix, pixel electrodes 4 also arranged in a matrix with an insulating layer 3 interposed, and deposited on these. The protective film 5 and the like are formed. On the other hand, on the surface of the glass substrate 6 on the liquid crystal 9 side, a transparent electrode 7 is deposited on the entire surface, and a black matrix or a black stripe 9b is formed at a position facing the MosFET 2 or the like. Then, by limiting the pixel electrode 4 to the upper surface region of the storage capacitor portion formed therebelow, the surface of the pixel electrode 4 is flattened.

The reflection type liquid crystal display device disclosed in Japanese Patent Laid-Open No. 148679/1994, whose cross section is shown in FIG. 5, has MosFETs 2 arranged in a matrix and an insulating layer on the surface of the silicon substrate 1. Pixel electrodes 4 which are also arranged in a matrix with 3 interposed, and a protective film 5 and the like deposited thereon are formed. Then, the surface of the pixel electrode 4 and the like is flattened by polishing the surface of the pixel electrode 4 and the protective film 5.

[0004]

As described above, in the conventional reflection type liquid crystal display device, the reflectance and the polarization controllability can be improved by limiting the forming range of the pixel electrode or polishing the surface after the pixel electrode is formed. The reflection surface is flattened to improve the reflection characteristics of.

However, when the formation range of the pixel electrode is limited, the planarization is achieved only partially, and the portions such as transistors and wirings on the silicon substrate must be shielded by the black matrix on the glass substrate. I won't.
For this reason, not only is the aperture ratio low, but there is also the inconvenience of requiring a laborious and difficult alignment operation when assembling the silicon substrate and the glass substrate.

Even when the surface after the pixel electrode is formed is polished, as described in Japanese Patent Laid-Open No. 148679/1994, a film much thicker than usual is laminated for a long time, and further polished until the unevenness disappears. Although it is possible experimentally, it is not preferable in practice because it causes an increase in processing cost.

Further, the sharpening condition is different between the part where the conductor pattern is dominant and the part where the conductor pattern is isolated and exists in a part of the inter-layer film where there are many interlayer films. Especially, it is difficult to flatten the latter part.

By the way, in a field where miniaturization of pixels is strongly required such as a projector, it is necessary to allocate an area which is considerably close to the area of the pixel electrode to the transistor in order to secure a desired switching characteristic. However, the aperture ratio is low and it is difficult to obtain the desired efficiency by arranging in a plane and limiting the formation range of the pixel electrode. For this reason, a three-dimensional panel structure in which the pixel electrodes are stacked above the transistor is supposed, but simply stacking them together causes the inconvenience as described above even if the surface is polished. Therefore, there is a problem to realize a panel structure in which a pixel electrode is stacked above a transistor, which is a so-called pixel electrode laminated type panel, but whose reflection surface is easily flattened.

The present invention has been made to solve the above problems, and an object thereof is to provide a reflection type liquid crystal display device having a flat reflection surface of a pixel electrode laminated type panel.

[0010]

The first to fifth solving means invented to solve such a problem are as follows.
The configuration and action and effect will be described below.

[First Solving Means] In the reflection type liquid crystal display device of the first solving means (as described in claim 1 at the beginning of the application), the panel is a semiconductor substrate and a transparent substrate facing the semiconductor substrate and these. Switching elements arranged in a matrix corresponding to a pixel array in a matrix on the liquid crystal side surface of the semiconductor substrate, and the liquid crystal sealed between the substrates, and the switching element above the switching elements. In a reflective liquid crystal display device in which pixel electrodes arranged in a matrix corresponding to a pixel array are formed, the switching element and the pixel electrode are provided between the switching element layer and the pixel electrode layer. Of the plurality of wiring layers, at least one of the plurality of wiring layers has at least a target portion of the pixel arrangement. And the wiring pattern of the eye, is characterized in that is made of the wiring pattern are integrally formed with the remaining pattern portion across a predetermined minimum insulation gap.

Here, the above-mentioned "predetermined minimum insulation gap" is the maximum required to secure insulation between adjacent patterns dynamically not only in static insulation but also in consideration of driving state. A gap that is the larger of the narrow gap and the minimum gap that can be stably processed, and that is provided around the wiring pattern part so that the gap is approximately this width at any of the gaps. . This gap may be filled with an insulating material or the like.

In the reflection type liquid crystal display device of the first means, the pixel electrode laminated type panel structure is adopted in order to secure a high aperture ratio. In order to secure a high aperture ratio by densely arranging pixel electrodes sandwiching an insulating gap between adjacent ones, a liquid crystal for switching the reflection state of incident light toward the semiconductor substrate through the transparent substrate for each pixel is provided. The pixel electrode laminated panel structure in which the pixel electrode to be driven is arranged above the switching element for controlling the pixel electrode is adopted, but a specific multilayer wiring layer is provided between the switching element layer and the pixel electrode layer. ing.

This wiring layer is originally necessary for connecting switching elements and pixel electrodes corresponding to each other, for shielding the transistor, and the like. At least one wiring layer is provided for at least pixels. In addition to the original connection wiring pattern portion, a residual pattern portion that is integrally formed with the wiring pattern remains in a substantially dense manner except for a predetermined minimum insulating gap. Therefore, in such a layer, the occurrence of an undesired step is limited to a small area of the minimum insulation gap portion, while in most of the wiring pattern portion and the remaining pattern portion, the step is not formed every time the layers are stacked. The corners, etc., become gentle.

As a result, since the surface of the upper layer is flattened as a whole, rough unevenness on the surface of the switching element layer can be attenuated by the presence of the multi-layer wiring layer in the middle, so that the surface of the pixel electrode is sufficient. Is flattened to.
Further, when the surface of the pixel electrode is directly used as a reflective surface, a sufficiently flat reflective surface can be obtained not only when the reflective surface is laminated above the pixel electrode layer.

Therefore, according to the present invention, it is possible to realize a reflection type liquid crystal display device in which the reflection surface of the pixel electrode laminated type panel is flat.

[Second Solving Means] The reflection type liquid crystal display device of the second solving means (as described in claim 2 at the beginning of the application) is the reflection type liquid crystal display device of the first solving means. Further, the pixel electrode is characterized in that the surface on the liquid crystal side is planarized by chemical mechanical polishing.

In the reflection type liquid crystal display device of the second means as described above, the surface of the pixel electrode and thus the reflection surface are further flattened by the chemical mechanical polishing, but as described above, the pixel electrodes are densely formed. Since it is not only provided but also has almost no unevenness, it is possible to obtain an extremely flat surface without spots by polishing a little. This makes it possible to avoid a long-time polishing process and a process of forming a thick pixel electrode layer in preparation for this polishing. As a result, even if the surface of the pixel electrode is polished, an increase in processing cost can be suppressed. In addition, since the pixel electrode is flat, the voltage applied to the liquid crystal between the pixel electrode and the transparent electrode becomes uniform.

Therefore, according to the present invention, a slight polishing of the surface of the pixel electrode realizes a reflection type liquid crystal display device in which the electric field applied to the liquid crystal is uniform and the reflection surface of the pixel electrode laminated type panel is flat. be able to.

[Third Solving Means] The reflection type liquid crystal display device of the third solving means (as described in claim 3 at the beginning of the application) is the reflection type liquid crystal of the above first or second solving means. In the display device, the pixel electrode includes an insulating layer that covers the wiring layer under the pixel electrode, and the surface of the insulating layer is planarized by chemical mechanical polishing. To do.

In the reflection type liquid crystal display device as the third means, the surface of the insulating layer covering the wiring layer is planarized by chemical mechanical polishing, and the pixel electrode is formed thereon. . As a result, even if a slight polishing process is performed, the unevenness is rapidly attenuated, and the pixel electrode surface becomes flatter.

Therefore, according to the present invention, it is possible to realize a reflection type liquid crystal display device in which the reflection surface of the pixel electrode laminated type panel is further flattened by slightly polishing the surface of the insulating layer.

[Fourth Solving Means] The reflection type liquid crystal display device of the fourth solving means (as described in claim 4 at the beginning of the application) is the reflection type liquid crystal of the above first to third solving means. A display device is provided with a protective layer covering the pixel electrode, and the protective layer is characterized in that the surface on the liquid crystal side is planarized by chemical mechanical polishing.

In the reflection type liquid crystal display device of the fourth means, the surface of the protective layer on the pixel electrode and thus the reflection surface is further flattened by the chemical mechanical polishing, which is the same as described above. For that reason, it is possible to obtain a very flat surface without spots, with only a little polishing.
As a result, similarly, avoiding a long polishing process,
An increase in processing cost can be suppressed.

Therefore, according to the present invention, it is possible to realize a reflection type liquid crystal display device in which the reflection surface of the pixel electrode laminated panel is flat by slightly polishing the protective layer covering the surface of the pixel electrode.

[Fifth Solving Means] The reflection type liquid crystal display device of the fifth solving means (as described in claim 5 at the beginning of the application) is the reflection type liquid crystal display device of the fourth solving means. It is characterized in that a dielectric mirror covering the protective layer is provided.

In the reflection type liquid crystal display device as the fifth means, the dielectric mirror functioning as a reflection surface is formed so as to cover the surface of the protective layer, and the surface of the protective layer is chemically formed. Since it is sufficiently flattened by mechanical polishing or the like, the reflecting surface is flattened without any special treatment on the dielectric mirror.

Therefore, according to the present invention, it is possible to realize a reflection type liquid crystal display device having a flat dielectric mirror by slightly polishing the protective layer covering the surface of the pixel electrode.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding the reflection type liquid crystal display device of the present invention achieved by the first to fifth means,
A mode for carrying out this will be described.

[First Embodiment] In the first embodiment of the present invention, in order to carry out the above-mentioned first solving means, the (display) panel has a (P-type or N-type). A semiconductor substrate (such as a silicon substrate) and a transparent substrate (such as a glass substrate or a quartz substrate) that faces the semiconductor substrate are sealed between these substrates (S
Liquid crystal (TN type, FLC type, etc.), and arranged in a matrix on the liquid crystal side surface of the semiconductor substrate (1 for each pixel).
Alternatively, in a reflective liquid crystal display device in which two or more switching elements such as P-channel / N-channel MOS transistors) and pixel electrodes arranged in a matrix corresponding to the pixel array are formed above the switching elements, A multi-layer provided between the layer of the switching element and the layer of the pixel electrode (with an interlayer insulating film or the like interposed) to connect the switching element and the pixel electrode corresponding to each other according to the pixel arrangement. (Al, W, Al alloy, Ti +
At least one (preferably all) of the multi-layered wiring layers is provided with at least a target portion of the pixel array (desirably including a peripheral portion). For the connection (drain line, source line, etc.)
A wiring pattern portion and a residual pattern portion (such as a dummy pattern) integrally formed with the wiring pattern (in the same photolithography process such as sputtering or vapor deposition) with a predetermined minimum insulation gap interposed therebetween. Is characterized in that.

[Second Embodiment] The second embodiment of the present invention is the reflection type liquid crystal display device of the first embodiment, wherein the characteristics of the transistor transistor are undesired due to incident light or leakage light. The pixel electrode is arranged so as to cover the transistor as the switching element in order to prevent it from being adversely affected, and the residual pattern portion is arranged under the gap between the pixel electrodes so as to block incident light leaking from the pixel electrode. In order to improve the aperture ratio or the reflectance, the pixel electrodes are densely arranged with a minimum gap required for insulation from an adjacent pixel electrode or a minimum gap that can be stably processed.

[Third Embodiment] The third embodiment of the present invention is the reflection type liquid crystal display device according to the first and second embodiments, in which the accuracy is improved by the chemical mechanical polishing process. For this reason, the residual patterns in the plurality of wiring layers and the pixel electrode layer are provided above the driving circuit and other peripheral circuits, and the plurality of interlayer insulations interposed in the plurality of wiring layers and the pixel electrodes. The film is made of the same material such as PSG and the manufacturing process is simple.

[Fourth Embodiment] The fourth embodiment of the present invention is the reflection type liquid crystal display device according to any one of the first to third embodiments, wherein the multi-layer structure is used for improving flatness. The wiring layer is also one whose surface has been subjected to chemical mechanical polishing. In this case, a slight polishing process is sufficient because it is an intermediate step.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific structure of a preferred embodiment of the reflection type liquid crystal display device of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of the panel cross section, but is an enlarged view of a certain pixel portion of a plurality of pixels.

In this reflection type liquid crystal display device, the display panel includes a P type silicon substrate 1, a glass substrate 6 facing the silicon substrate 1 with a spacer or the like partially interposed therebetween, and vacuum suction between these substrates. And the liquid crystal 9 enclosed by the above.

The glass substrate 6 has a transparent electrode 7 made of ITO or the like, which is held at a common voltage or is grounded, and an alignment film 8 made of an obliquely vapor-deposited silicon oxide film, on the surface of the liquid crystal 9 side.
Are laminated. Note that the black matrix is excluded.

The liquid crystal 9 is a vertical alignment type nematic liquid crystal.

In the silicon substrate 1, the source 11 receives a data signal via the source line 31S and the polysilicon gate 12 receives a scan signal corresponding to one of the pixels arranged in a matrix on the surface of the liquid crystal 9 side. Receiving drain 1
3 is a P-channel MO connected to the drain line 31D.
S transistor 10 and source 21 are connected to source line 3
A polysilicon gate 22 receives a data signal via 1S.
Receives a scan signal and drain 23 is drain line 3
N-channel MOS transistor 20 connected to 1D
A pixel electrode 34D which is separated from the adjacent pixel electrode by a slight insulating gap in the pixel electrode layer 34 above the pixel electrode 34D and is densely patterned; and a transistor which is patterned in the wiring layers 31, 32 and 33, respectively. Drain lines 31D, 3 connecting the drains of the pixels 10, 20 and the pixel electrode 34D
2D and 33D are provided. The other pixel portions are similar.

Insulating films 40 and interlayer insulating films 41, 42 and 43 are alternately laminated between the layers of the transistors 10 and 20, the wiring layers 31, 32 and 33 and the pixel electrode layer 34. ing. Here, the wiring layers 31, 32, 33
The pixel electrode layer 34 is formed of an aluminum (Al) film. The insulating films 40 to 43 are formed of a phosphor silicate glass (PSG) film, and are made of the same material in all layers. After forming the interlayer insulating film 43,
The surface is subjected to chemical mechanical polishing polishing treatment. This is to obtain the flatness of the electrodes and the uniformity of the electric field.

Further, on the pixel electrode layer 34, a protective film 50 made of a silicon oxide film or a silicon nitride film, a dielectric mirror 51 for reflecting incident light, and an alignment film made of a silicon oxide film obliquely deposited. 52 and 52 are sequentially stacked.

By adopting such a structure, this reflection type liquid crystal display device can be manufactured by a general silicon process for manufacturing CMOS or a liquid crystal panel manufacturing process. Therefore, although the description of the general technique is omitted, in the panel of this reflective liquid crystal display device, the wiring layer 3
2 and 33 are patterned to form drain lines 32D and 3D
When forming the 3D, only the minimum width required for the insulation or processing of the drain lines 32D and 33D is removed by etching. As a result, the remaining pattern portions such as the dummy patterns 32F and 33F are formed simultaneously with the drain line 32D and the like without adding a new process. The dummy pattern 33F and the like are
It is arranged under the gap between the pixel electrode 34D and its adjacent pixel electrode, and also shields the leaked incident light so that it does not reach the resonators 10 and 20.

After the pixel electrode layer 34 is formed, its surface is subjected to chemical mechanical polishing for a short time, and after the protective film 50 is formed, its surface is subjected to mirror surface chemical mechanical polishing. Give. This makes it possible to sufficiently flatten the reflecting surface of the dielectric mirror 51 while suppressing the additional processing to a slight amount.

The specific operation of the reflective liquid crystal display device of this embodiment will be described with reference to the drawings. FIG. 2 is a block diagram of the equivalent circuit, and FIG. 3 is a waveform example of a drive signal.

The liquid crystal 9 is driven by the line-sequential active matrix method. That is, the data signal for each column corresponding to one horizontal scanning line is output in parallel to the data lines A1 to An from the column electrode driving circuit, and the polarity of the scanning signal of the row corresponding to the scanning line is output from the row electrode driving circuit. Are sequentially output to the scan lines X1, Y1 and the like. This pulse output is applied to the line X every horizontal scanning.
1, Y1 to lines X2, Y2 and lines X3, Y3
It transits in order.

Here, taking the pixel in the second row and the second column as an example,
In this pixel, when the P-channel MOS transistor 10 receives a negative scan pulse on the gate 12 via the line X2 and the N-channel MOS transistor 20 simultaneously receives a positive scan pulse on the gate 22 via the line Y2, the MOS is generated. Both the transistors 10 and 20 are turned on, and the sources 12 and 22 and the drains 13 and 23 are electrically connected. Then, the voltage of the data signal output on line A2 is
It is applied to the pixel electrode 34D via the source line 31S, the transistors 10 and 20, and the drain lines 31D, 32D, and 33D. Next, when a ground potential is applied to the gate 12 of the P-channel MOS transistor 10 and the gate 22 of the N-channel MOS transistor 20, the MO
The S transistors 10 and 20 are both turned off and the pixel electrode 3
4D holds the voltage of the data signal.

Then, the liquid crystal 9 in the portion above the pixel electrode 34D changes its polarization state according to the voltage difference between the applied voltage of the pixel electrode 34D and the common voltage of the transparent electrode 7, so that it is projected from a light source (not shown). It is possible to control the ratio of the reflected light to the projection surface (not shown) with respect to the incident light. In this reflected light state, the electric field applied to the liquid crystal 9 is uniform because the surface of the pixel electrode 34D is flat, and the reflecting surface is an optical mirror surface because the surface of the dielectric mirror 51 is flat. Since the thickness of the liquid crystal 9 is uniform, it is extremely good. The same applies to other pixels. Therefore, a clear image can be projected on the projection surface without the black matrix.

Although the reflection type liquid crystal display device having no black matrix on the glass substrate has been described above, the present invention is effective even when the glass substrate is provided with the black matrix. Even if the black matrix is provided, since the reflection surface is flat and the reflection characteristics are good, it is only necessary to provide the portion corresponding to a small gap between the pixel electrodes densely arranged, so that a high aperture ratio is maintained. Can be done.

[0048]

As is apparent from the above description, in the reflection type liquid crystal display device of the first solution of the present invention, the unevenness is reduced by the multilayer wiring layer in the middle,
The surface of the pixel electrode is sufficiently flattened, and as a result, reflection characteristics such as reflectance and polarization controllability are improved. Therefore, there is an advantageous effect that it is possible to realize a reflection type liquid crystal display device in which the reflection surface of the pixel electrode laminated type panel is flat.

In the reflection type liquid crystal display device according to the second solution of the present invention, by slightly polishing the surface of the pixel electrode, the electric field applied to the liquid crystal is uniform and the pixel electrode laminated type The advantageous effect that a reflective liquid crystal display device in which the reflective surface of the panel is flat can be realized is achieved.

Further, in the reflection type liquid crystal display device of the third means of the present invention, the reflection type liquid crystal display in which the reflection surface of the pixel electrode laminated type panel is flat by slightly polishing the surface of the insulating layer. The advantage is that the device can be realized.

Further, in the reflection type liquid crystal display device of the fourth solution of the present invention, the reflection surface of the pixel electrode laminated type panel is made flat by slightly polishing the protective layer above the pixel electrode surface. This has an advantageous effect that a reflective liquid crystal display device can be realized.

Further, in the reflection type liquid crystal display device of the fifth means of the present invention, even if the dielectric mirror is not subjected to any special treatment, the protective layer covering the surface of the pixel electrode is slightly polished, There is an advantageous effect that a reflection type liquid crystal display device having a flat dielectric mirror can be realized.

[Brief description of drawings]

FIG. 1 is an enlarged schematic view of a panel cross section of a reflective liquid crystal display device of the present invention.

FIG. 2 is a block diagram of an equivalent circuit of the device.

FIG. 3 is a waveform diagram of the drive signal.

FIG. 4 is a schematic sectional view of a conventional liquid crystal display panel.

FIG. 5 is a schematic sectional view of a conventional liquid crystal display panel.

[Description of Reference Signs] 1 Silicon substrate (semiconductor substrate) 2 MosFET 3 Insulating layer 3a Field oxide film 4 Pixel electrode 5 Protective film 6 Glass substrate (Transparent substrate) 7 Transparent electrode 8 Alignment film 9 Liquid crystal 10 P-channel MOS transistor (PchMos)
FET) 11 source 12 gate 13 drain 20 N-channel MOS transistor (NchMos)
FET) 21 source 22 gate 23 drain 31 wiring layer 31S source line (wiring pattern portion) 31D drain line (wiring pattern portion) 32 wiring layer 32D drain line (wiring pattern portion) 32F dummy pattern (remaining pattern portion) 33 wiring layer 34 Pixel electrode layer 34D Pixel electrode 40 Insulating film 41 Interlayer insulating film 42 Interlayer insulating film 43 Interlayer insulating film 50 Protective film 51 Dielectric mirror 52 Alignment film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Hanada, 465 Ozato-cho, Kofu-shi, Yamanashi Pioneer Video Co., Ltd., Kokumo Factory (72) Motohisa Oguni, 465, Oza-cho, Kofu-shi, Yamanashi Pioneer Video Co., Ltd., Kokumo Factory Within

Claims (5)

[Claims] 1. A panel comprises a semiconductor substrate, a transparent substrate facing the semiconductor substrate, and liquid crystal enclosed between these substrates, and a liquid crystal surface of the semiconductor substrate corresponding to a pixel array on the liquid crystal side surface. In a reflective liquid crystal display device in which switching elements arranged in a matrix are formed, and pixel electrodes arranged in a matrix corresponding to the pixel array are formed above the switching elements, the layers of the switching elements and the pixel electrodes. A wiring layer provided between the switching element and the pixel electrode and corresponding to each other according to the pixel arrangement, and at least one of the wiring layers is at least The target portion of the pixel array is composed of a wiring pattern portion for the connection and a residual pattern portion integrally formed with the wiring pattern with a predetermined minimum insulation gap interposed therebetween. Reflection type liquid crystal display device, characterized in that those. 2. The reflection type liquid crystal display device according to claim 1, wherein the pixel electrode has a surface on the liquid crystal side which is flattened by chemical mechanical polishing. 3. The pixel electrode includes an insulating layer that covers the wiring layer under the pixel electrode, and the surface of the insulating layer is planarized by chemical mechanical polishing. The reflective liquid crystal display device according to claim 1. 4. A protective layer for covering the pixel electrode is provided, and the protective layer has a surface on the liquid crystal side which is planarized by chemical mechanical polishing.
The reflective liquid crystal display device according to claim 1. 5. The reflection type liquid crystal display device according to claim 4, further comprising a dielectric mirror that covers the protective layer.