JPH1164872A - Reflection type liquid crystal display element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display element which can be easily manufactured and has high display grade and a manufacturing method therefor. SOLUTION: In a TFT substrate 1, a surface protective layer 21a having strength higher than that of aluminium is formed on a reflection pixel electrode 21 made of an aluminium thin film and a vertically oriented film 7 is formed thereon. As the surface protective layer 21a, an aluminium oxide film formed by anodically oxidizing a surface of the reflection pixel electrode 21 and an aluminium oxide film formed by sputtering and a silicon oxide film, etc., are used.

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 having a reflection electrode, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been actively developed to replace CRTs. Among them, for use in portable information terminals, natural light such as outdoors or light incident from outside such as indoor lighting is reflected. There is a reflection type liquid crystal display element which performs display by causing the display to be performed. Since this does not require a backlight as a light source, power consumption is reduced, and at the same time, it is possible to reduce the thickness and weight.

As a liquid crystal display element used for projection, a reflective liquid crystal display element is being developed. This is because it has a reflective electrode as a pixel electrode,
This is because an active element for driving the pixel electrode can be formed below the reflective electrode, and there is an advantage that the aperture ratio can be increased. Thus, the development of a liquid crystal display device having a reflective electrode has attracted attention.

FIG. 6 shows a TFT (Th) as an active element.
1 shows an example of a configuration of a conventional reflective liquid crystal display device using an in-film transistor.

[0005] The reflection type liquid crystal display device has a TFT having a TFT.
The FT substrate 31 and the counter substrate 32 are bonded together via a sealing resin including a spacer (not shown), and a liquid crystal layer 33 is formed in a space formed between the substrates 31 and 32.

[0006] The TFT substrate 31 is made of an insulating substrate 34.
Above, a plurality of gate bus lines (not shown) are provided in parallel with each other, and a gate electrode 41 is branched from each gate bus line. And, this gate electrode 41
, A gate insulating film 42 is formed on the entire surface,
On the gate insulating film 42 above the gate electrode 41, a semiconductor layer 43 and a contact layer 43a are sequentially formed.

A source electrode 44 is formed on one end of the contact layer 43a, and a drain electrode 45 made of the same material as the source electrode 44 is formed on the other end. A source bus wiring (not shown) crossing the gate bus wiring with the gate insulating film 42 interposed therebetween is connected to the electrode 44. The source bus wiring is also formed of the same metal as the source electrode 44.

The gate electrode 41 and the gate insulating film 4
2, semiconductor layer 43, contact layer 43a, source electrode 4
4 and the drain electrode 45 are connected to a switching element T
The FT 48 is configured.

A flattening film 50 is formed on the entire surface of the upper substrate of the TFT 48, and the drain electrode 4 of the flattening film 50 is formed.
Contact holes 52 are formed in the five portions to be electrically connected to the reflection pixel electrodes 51. The reflective pixel electrode 5 made of aluminum is provided on the flattening film 50.
The reflective pixel electrode 51 is electrically connected to the drain electrode 45 through the contact hole 52. On the surface of the reflective pixel electrode 51, an alignment film 37 for aligning liquid crystal molecules is formed.

On the other hand, an opposing substrate 32 is formed on an insulating substrate 38 such as glass by covering the entire pixel region with ITO (Indium Ti).
n Oxide), etc.
An alignment film 40 is formed thereon.

By the way, in these reflective liquid crystal display devices, aluminum having high reflectance is mainly used as the reflective pixel electrode 51 in order to obtain brighter reflected output light.

One example is disclosed in Japanese Patent Application Laid-Open No. 6-347828.
Japanese Patent Application Laid-Open Publication No. H11-157, discloses that an active element is formed on single-crystal silicon, aluminum is formed as a reflective pixel electrode by evaporation, and the surface is polished. According to this, hillocks generated on the electrode surface can be prevented, and as a result, high reflectance characteristics can be obtained by preventing light scattering.

[0013]

In the above-mentioned publication, however, the reflective pixel electrode made of aluminum is polished to prevent hillocks. However, in the process of firing the alignment film, hillocks generated by heating are not considered. ,
Not considered.

That is, as shown in FIG. 6, an alignment film 37 is coated on the reflective pixel electrode 51 with, for example, polyimide or the like, and is baked. Thereafter, the alignment film 37 determines the alignment direction of the liquid crystal molecules. Since it is formed by performing a rubbing process of rubbing with a cotton cloth or the like as a process, even if the surface of the reflective pixel electrode 51 is polished, the alignment film 37 to be subsequently performed is formed.
During the firing process, hillocks may be generated on the reflective pixel electrode 51.

If the generated hillock has a size of several μm larger than the cell gap, the counter electrode 39 and the reflection pixel electrode 51 provided on the counter substrate 32 via the hillock are provided.
Are conducted, and a vertical leak occurs. Further, hillocks are scraped off by the rubbing treatment, which causes dust generation. Further, when a display is performed as a liquid crystal display element, alignment disorder of liquid crystal molecules occurs near a hillock on the reflective pixel electrode 51. As a result, light leakage occurs at the time of dark display and the reflectivity at the time of bright display. As a result, the contrast is lowered to lower the display quality.

[0016] Even if no hillocks occur,
As a result of the above-described rubbing treatment, traces rubbed with a cotton cloth or the like remain as scratches 55 on the surface of the reflective pixel electrode 51 as shown in FIG. This is because the intensity of the reflective pixel electrode 51 made of aluminum is low, and the surface is rubbed with a predetermined cloth. As a result, a part of the reflective pixel electrode 51 is shaved and irregularities are generated on its surface. In the worst case, the reflective pixel electrode 51 in this part is absent.

As a result, as in the case where the alignment of the liquid crystal molecules is disturbed and a hillock is generated in the reflective pixel electrode 51, the contrast becomes low due to light leakage or a decrease in the maximum reflectance.
The display quality will be degraded. The hatched area BM in the figure indicates the gate bus wiring and the source bus wiring described above.
This is a black matrix that covers the TFT 48.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a reflective liquid crystal display element which can be easily manufactured and has high display quality, and a method of manufacturing the same.

[0019]

In order to solve the above-mentioned problems, in the reflection type liquid crystal display device of the present invention, a liquid crystal is sandwiched between a pair of substrates each having an electrode, and one of the pair of substrates is provided. In a reflection type liquid crystal display device having a reflection electrode made of an aluminum thin film as one electrode, a surface protection layer having higher strength than aluminum is formed on the surface of the pixel electrode.

In order to solve the above-mentioned problems, a method of manufacturing a reflection type liquid crystal display element according to the present invention comprises interposing a liquid crystal between a pair of substrates each having an electrode, and providing one of the pair of substrates. A reflective electrode comprising an aluminum thin film as an electrode, and a reflective liquid crystal display element manufacturing method in which an alignment film for aligning liquid crystal molecules is formed on the reflective electrode. Before the formation, a surface protective layer having higher strength than aluminum is formed on the surface of the reflective electrode.

According to the above, the surface protection layer formed on the surface of the reflective electrode prevents hillocks of the reflective electrode during firing of the alignment film, and makes hillocks less likely to occur. Therefore, the above-described vertical leakage due to hillocks and the generation of dust during rubbing are unlikely to occur. In addition, light leakage due to disturbance of the alignment of liquid crystal molecules near the hillocks during display and reduction in the maximum reflectivity do not occur, and the display quality with high contrast is excellent.

Further, the surface protection layer makes it difficult for the surface of the reflective electrode to be easily scratched, which is liable to occur in the rubbing treatment, and does not cause a deterioration in display quality due to disorder in the alignment of liquid crystal molecules caused by the scratch.

The above-mentioned surface protective layer is formed of a film formed by anodizing the surface of the reflective electrode, a film made of aluminum oxide formed by sputtering, or a silicon oxide formed by sputtering. There are membranes and the like.

Among them, the method of forming the surface protective layer by anodizing the surface of the reflective electrode does not require a sputtering apparatus and a portion other than the reflective electrode, as compared with a method of forming a film by sputtering, for example. There is an advantage that there is no need for masking and manufacturing is easy. Conversely,
The method of forming a surface protective layer made of an aluminum oxide or silicon oxide film using a sputtering apparatus is slightly more complicated than the anodic oxidation method, but has an advantage that the thickness can be easily controlled. There is.

In the above-mentioned reflection type liquid crystal display element of the present invention, the same material as the surface protective layer provided on the surface of the reflective electrode is provided on the electrode surface of the other substrate which is disposed opposite to the substrate having the reflective electrode. May be formed.

According to this, in both substrates, the film closest to the liquid crystal is made of the same material, so that the lines of electric force generated when a voltage is applied to the liquid crystal layer become uniform, and disclination occurs. Can be prevented.

Further, in this case, by forming the film made of the same material as the surface protective layer to have the same thickness as the surface protective layer, the occurrence of disclination can be more effectively prevented.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] Regarding one embodiment of the present invention,
This will be described with reference to FIGS. 1 to 4.

FIG. 1 is a sectional view of a principal part showing a reflection type liquid crystal display device of the present embodiment, and FIG. 2 is a plan view of a substrate having an active element constituting the reflection type liquid crystal display device. is there. Here, a so-called active matrix driven device using an active element is exemplified. However, it is needless to say that the present invention can be applied to a reflection type liquid crystal display device driven by a simple matrix.

This reflection type liquid crystal display element has a TFT (Thin Filtration) as an active element on one side with a liquid crystal layer 3 interposed therebetween.
m Transistor), and a counter substrate 2 on the other side.

In the TFT substrate 1, a plurality of gate bus lines 5 made of chromium, tantalum or the like are provided in parallel with each other on an insulating substrate 4 made of glass or the like. Are provided in a branched manner. A gate insulating film 12 made of silicon nitride (SiNx), silicon oxide (SiOx), or the like is formed on the entire surface so as to cover the gate electrode 11.

Gate insulating film 12 above gate electrode 11
A semiconductor layer 13 and a contact layer 1 made of a-Si (amorphous silicon), polycrystalline silicon, or the like.
3a are sequentially formed, and a source electrode 14 made of titanium, molybdenum, aluminum, or the like is formed on one end of the contact layer 13a so as to overlap.

The source electrode 14 is connected to a source bus line 6 which intersects the gate bus line 5 with the gate insulating film 12 interposed therebetween. The source bus line 6 is also made of the same metal as the source electrode 14. Is formed.

On the other end of the contact layer 13a, a drain electrode 15 made of titanium, molybdenum, aluminum or the like similar to the source electrode 14 is formed so as to overlap. The gate electrode 11, the gate insulating film 12, the semiconductor layer 13, the contact layer 13a, the source electrode 14 and the drain electrode 15 are TFTs 18 serving as switching elements.
Is composed.

A flattening film 20 made of polyimide or the like is formed on the entire surface of the upper substrate of the TFT 18. The drain electrode 15 of the flattening film 20 is electrically connected to a reflective pixel electrode (reflective electrode) 21. A contact hole 22 is formed for connection.

A reflective pixel electrode 21 made of aluminum is formed on the flattening film 20 so as to overlap, and the reflective pixel electrode 21 is electrically connected to the drain electrode 15 through the contact hole 22. The thickness of the reflective pixel electrode 21 is 3000 to 5000 degrees.

Further, a surface protection layer 21 for protecting the surface of the reflective pixel electrode 21 is provided on the surface of the reflective pixel electrode 21.
a is formed, and further covers this surface protective layer 21a,
A vertical alignment film 7 for aligning liquid crystal molecules is formed.

The surface protective layer 21a is a film having a strength higher than that of aluminum. For example, aluminum oxide (Al ₂ O ₃ ) formed by anodizing the surface of the reflective pixel electrode 21 or sputtering. Formed a film,
Aluminum oxide, silicon oxide, titanium oxide such as TiO ₂ , and tantalum oxide such as Ta ₂ O ₅ can be used.

Here, the thickness of the aluminum oxide film formed by the anodizing treatment, or the film formed of the aluminum oxide, silicon oxide, titanium oxide, tantalum oxide or the like formed by the sputtering method is 1000 to 2000 mm. is there.
This is because if the thickness is less than 1000 °, the strength is reduced and the function of protecting the surface of the reflective pixel electrode 21 is hindered.
Conversely, if the thickness is more than 2000 °, the voltage applied to the liquid crystal layer 3 must be set higher than necessary. And, more preferably, the film thickness is 1400 to 1800.
Å.

On the other hand, the opposing substrate 2 is made of an indium tin oxide (ITO) on the entire surface of the pixel region on an insulating substrate 8 such as glass.
A transparent counter electrode 9 made of ide) or the like is formed, and a vertical alignment film 10 is formed thereon.

The TFT substrate 1 and the counter substrate 2 are bonded together via a sealing resin including a spacer (not shown), and a liquid crystal is injected into a space formed between the substrates 1 and 2 so that liquid crystal is injected. The liquid crystal layer 3 is formed.

One method of manufacturing such a reflection type liquid crystal display device will be described below with reference to FIGS. First, a metal film such as tantalum is deposited on the substrate 1 by a sputtering method, and is patterned by photolithography to form the gate bus wiring 5 and the gate electrode 11.

Next, a SiNx film serving as a gate insulating film 12, a semiconductor layer 13, and a contact layer 1 are formed by plasma CVD.
Each semiconductor film 3a is continuously formed, and the semiconductor layer 13 and the contact layer 13a are simultaneously patterned by photolithography, and subsequently, a gap portion of the contact layer 13a is patterned.

Next, a metal film such as titanium or molybdenum is formed and patterned by photolithography to form a source electrode 14 and a drain electrode 15. Thus, the TFT 18 is manufactured. In addition, as a method of manufacturing the TFT 18, various conventional methods other than the above can be used.

On the substrate 4 on which the TFT 18 is formed,
A polyimide as the flattening film 20 is formed by a spin coating method or the like. Subsequently, a contact hole 22 penetrating the flattening film 20 is formed by photolithography or the like. A metal film is formed by sputtering and patterned.

Subsequently, the substrate 4 on which the components up to the reflective pixel electrode 21 are formed is immersed in a hydrogen peroxide solution or a nitric acid solution at room temperature, and a current is applied to the reflective pixel electrode 21 for 3 to 10 minutes. The surface of the aluminum thin film that is the reflective pixel electrode 21 is oxidized to a thickness of 1000 to 2000 to form aluminum oxide, thereby forming the surface protection layer 21a.

Alternatively, the substrate 4 on which the reflective pixel electrode 21 is formed is put into a sputtering device, and the reflective pixel electrode 21 is formed on the reflective pixel electrode 21 by a sputtering method at a temperature of 1000 ° to 2 °.
Aluminum oxide, silicon oxide, titanium oxide and tantalum oxide are formed to a thickness of 2,000
a is formed. The film formation here is performed by performing RF plasma discharge in an argon (Ar) atmosphere to perform sputtering.

Thereafter, polyimide or the like is applied so as to cover the substrate 4 on which the surface protective layer 21a is formed, to form the vertical alignment film 7, and the vertical alignment film 7 is baked at a temperature of 170 ° C.

In the counter substrate 2, a counter electrode 9 made of ITO is formed on the substrate 8 by sputtering or the like, and a polyimide or the like is coated thereon so as to cover the substrate 8 similarly to the TFT substrate 1. To form a vertical alignment film 10,
The vertical alignment film 10 is fired.

Thereafter, a rubbing treatment is performed on the vertical alignment films 7 and 10 with a cotton cloth or the like in order to align the liquid crystal molecules. Further, the vertical alignment films 7 and 10 are formed between the TFT substrate 1 and the counter substrate 2. The surfaces on the opposite sides are opposed to each other and bonded together via a sealing resin (not shown) mixed with a 4 μm spacer.

Thereafter, the liquid crystal is injected from the injection port into the space formed between the substrates 1 and 2 by vacuum injection.
A liquid crystal layer 3 is formed between the two, and the inlet is sealed. Thus, the reflection type liquid crystal display device shown in FIG. 1 is completed.

As described above, in the reflection type liquid crystal display element of the present embodiment, since the surface protection layer 21 a having a higher strength than aluminum is formed on the reflection pixel electrode 21, the baking of the vertical alignment film 7 is prevented. Even after the heat treatment, generation of hillocks in the reflective pixel electrode 21 made of the aluminum thin film is prevented.

Therefore, no vertical leakage due to the hillocks occurs, and the hillocks are not scraped off by the rubbing treatment, thereby causing no dust. Furthermore, the display quality is good without causing light leakage when no voltage is applied due to the disorder of alignment of the liquid crystal molecules near the hillock and low contrast due to a decrease in reflectance when voltage is applied.

Further, as shown in FIG. 3, the surface protective layer 21a formed on the reflective pixel electrode 21 can prevent the reflective pixel electrode 21 from being scratched during rubbing.

Here, the voltage-reflectance characteristics of the device of one example having the structure of the reflection type liquid crystal display device of the present embodiment are shown by a solid line in FIG. For comparison, FIG. 4 also shows the voltage-reflectance characteristics of the reflection-type liquid crystal display device having the conventional structure by a dashed line.

FIG. 4 shows that the reflective liquid crystal display device of the present embodiment can obtain a higher reflectivity in a bright display when a voltage is applied and a darker display when no voltage is applied, as compared with the conventional one. It can be seen that a good black level was obtained, the contrast was improved, and the display quality was good.

In this embodiment, the case where the TFT 18 is used as the switching element has been described.
Of course, it is possible to use a two-terminal element such as an MIM or a diode element. Also, here, the vertical alignment film 7 is used.
Although 10 is used, the same effect can be obtained when a parallel alignment film is used instead of the vertical alignment films 7 and 10. In addition, although only the counter electrode 9 and the vertical alignment film 10 are formed on the counter substrate 2, a structure in which a color filter is formed below the counter electrode 9 may be used.

Although not particularly specified, the surface of the reflective pixel electrode 21 may be subjected to a mirror finishing process such as polishing or a flattening process between the reflective pixel electrodes 21. In addition, since the surface of the reflective pixel electrode 21 has a mirror surface, excellent reflectivity characteristics can be obtained, and since the uniformity of alignment of liquid crystal molecules is excellent, higher contrast can be obtained.

[Second Embodiment] The following will describe another embodiment of the present invention with reference to FIG. For the sake of convenience, members having the same functions as those described in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

FIG. 5 is a cross-sectional view of a principal part showing a reflection type liquid crystal display device of the present embodiment. The difference between the reflective liquid crystal display element shown in FIG. 5 and the reflective liquid crystal display element of the first embodiment shown in FIG. 1 is that in the reflective liquid crystal display element of the present embodiment, the reflection of the TFT substrate 1 The point is that a film 24 made of the same material as the surface protection layer 21 a formed on the surface of the pixel electrode 21 is formed on the counter electrode 9 of the counter substrate 23.

By forming such a film 24 on the opposite substrate 23, the film closest to the liquid crystal layer 3 formed between the TFT substrate 1 and the opposite substrate 23 has the same material on both the TFT side and the opposite side. Therefore, the lines of electric force generated when a voltage is applied to the liquid crystal layer 3 become uniform, and the effect that disclination can be prevented can be achieved.

Further, in this case, it is desirable that the film thickness of the surface protection layer 21a formed on the TFT substrate 1 and the film 24 formed on the counter substrate 23 be equal to each other, so that the occurrence of disclination is more effectively prevented. Can be prevented.

[0063]

As described above, in the reflection type liquid crystal display device according to the first aspect of the present invention, the liquid crystal is sandwiched between a pair of substrates each having an electrode, and one of the electrodes of the pair of substrates is disposed. In a reflective liquid crystal display device having a reflective electrode made of an aluminum thin film, a surface protective layer having higher strength than aluminum is formed on the surface of the reflective electrode.

A reflective liquid crystal display element according to a second aspect of the present invention has a structure according to the first aspect, wherein the surface protective layer is a film formed by anodizing the surface of the reflective electrode.

A reflective liquid crystal display device according to a third aspect of the present invention has a structure according to the first aspect, wherein the surface protective layer is a film made of aluminum oxide.

A reflective liquid crystal display device according to a fourth aspect of the present invention has a structure according to the first aspect, wherein the surface protective layer is a film made of silicon oxide.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a reflective liquid crystal display device, wherein a liquid crystal is sandwiched between a pair of substrates each having an electrode, and one of the pair of substrates is formed of an aluminum thin film. In a method of manufacturing a reflective liquid crystal display device, comprising a reflective electrode, and an alignment film for aligning liquid crystal molecules formed on the reflective electrode, before forming an alignment film on the reflective electrode, A surface protective layer having a higher strength than aluminum is formed on the surface of the reflective electrode.

According to a method of manufacturing a reflection type liquid crystal display device according to an eighth aspect of the present invention, in the method of the seventh aspect, the surface protective layer is formed by anodizing the surface of the reflective electrode. .

According to a ninth aspect of the present invention, in the method for manufacturing a reflection type liquid crystal display element according to the ninth aspect, the surface protection layer is formed by forming a film made of aluminum oxide on the surface of the reflective electrode by sputtering. It is formed by forming a film.

According to a tenth aspect of the present invention, in the method for manufacturing a reflective liquid crystal display element, the surface protective layer is formed by forming a film made of silicon oxide on the surface of the reflective electrode by sputtering. It is formed by forming a film.

As a result, the occurrence of hillocks in the reflective electrode during firing of the alignment film is prevented, and hillocks are hardly generated. Therefore, vertical leakage due to hillocks, dust during rubbing is hardly generated, and display is not performed. In this case, there is no light leakage due to the disorder of the alignment of the liquid crystal molecules near the hillocks or a decrease in the maximum reflectance, and the display quality with high contrast is excellent.

Further, the surface protective layer makes it difficult for the surface of the reflective electrode to be easily scratched, which is liable to occur in the rubbing treatment, and does not cause a deterioration in display quality due to disorder in the alignment of liquid crystal molecules caused by the scratch.

As a result, with such a simple structure in which the surface protective layer is provided on the reflective electrode surface and the manufacturing process,
The flatness of the reflective electrode surface is maintained, and the reflectance in dark display is kept lower than in the past, and high reflectance characteristics can be obtained in bright display, so that bright display can be performed.
There is an effect that a reflective liquid crystal display device having high contrast and excellent display quality can be provided.

As the surface protective layer, a film formed by anodizing the surface of the reflective electrode, a film made of aluminum oxide formed by sputtering, or a silicon oxide formed by sputtering. There are membranes and the like.

Of these methods, the method of forming a surface protective layer by anodizing the surface of the reflective electrode does not require a sputtering apparatus and a portion other than the reflective electrode, for example, as compared with a method of forming a film by sputtering. This eliminates the need for masking and facilitates manufacture. Conversely, a method of forming a surface protection layer made of an aluminum oxide or silicon oxide film using a sputtering apparatus is as follows.
Although the production is slightly more complicated than the method of anodizing,
This has the effect of easily controlling the film thickness.

According to a fifth aspect of the present invention, there is provided a reflective liquid crystal display device according to the first, second, third or fourth aspect, wherein the electrode surface of the other substrate is provided so as to face the substrate having the reflective electrode. In addition, a film made of the same material as the surface protective layer provided on the reflective electrode surface is formed.

As a result, the lines of electric force generated when a voltage is applied to the liquid crystal layer become uniform.
Or, in addition to the effect of the configuration of 4, the disclination can be prevented from occurring, and the display quality can be further improved.

According to a sixth aspect of the present invention, in the reflection type liquid crystal display device, the film of the same material as the surface protective layer has the same thickness as the surface protective layer. .

As a result, the lines of electric force generated when a voltage is applied to the liquid crystal layer become more uniform than in the structure of claim 5, so that the occurrence of disclination can be prevented more effectively. There is an effect that the display quality can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part showing a structure of a reflective liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a plan view of a principal part showing a configuration of a substrate having an active element constituting the reflective liquid crystal display element of FIG. 1;

3 is an explanatory diagram showing a surface state of a reflective pixel electrode when a rubbing process is performed on an alignment film on a substrate having an active element in FIG. 2;

FIG. 4 is a graph showing voltage-reflectance characteristics of the reflective liquid crystal display device of the embodiment having the configuration of the reflective liquid crystal display device of FIG. 1 and a reflective liquid crystal display device of a conventional structure.

FIG. 5 is a cross-sectional view of a principal part showing a structure of a reflection type liquid crystal display element according to another embodiment of the present invention.

FIG. 6 is a sectional view of a main part showing a structure of a conventional reflective liquid crystal display element.

FIG. 7 is an explanatory diagram showing a surface state of a reflective pixel electrode when a rubbing process is performed on an alignment film on a substrate having an active element in a reflective liquid crystal display element having a conventional structure.

[Explanation of symbols]

 Reference Signs List 1 TFT substrate (substrate) 2 Counter substrate (substrate) 3 Liquid crystal layer (liquid crystal) 7 Vertical alignment film (alignment film) 9 Counter electrode 10 Vertical alignment film (alignment film) 18 TFT 21 Reflection pixel electrode (reflection electrode) 21a Surface protection Layer 23 Counter substrate 24 Film (film of the same material as surface protective layer) BM Black matrix

Claims (10)

[Claims] 1. A reflection type liquid crystal display device having a liquid crystal sandwiched between a pair of substrates each having an electrode and having a reflection electrode made of an aluminum thin film as one of the electrodes of the pair of substrates. A reflective liquid crystal display device, wherein a surface protective layer having higher strength than aluminum is formed on the surface. 2. A reflective liquid crystal display device according to claim 1, wherein said surface protective layer is a film formed by anodizing the surface of a reflective electrode. 3. The reflective liquid crystal display device according to claim 1, wherein said surface protective layer is a film made of aluminum oxide. 4. The reflective liquid crystal display device according to claim 1, wherein said surface protective layer is a film made of silicon oxide. 5. A film having the same material as a surface protective layer provided on a surface of a reflective electrode is formed on an electrode surface of another substrate provided opposite to a substrate having a reflective electrode. The reflective liquid crystal display device according to claim 1, 2, 3, or 4. 6. The film of the same material as the surface protective layer has the same thickness as the surface protective layer.
The reflective liquid crystal display element as described in the above. 7. A liquid crystal is sandwiched between a pair of substrates each having an electrode, and a reflective electrode made of an aluminum thin film is provided as one of the pair of substrates, and liquid crystal molecules are formed on the reflective electrode. In a method of manufacturing a reflective liquid crystal display device having an alignment film for aligning, before forming an alignment film on the reflective electrode, forming a surface protective layer having a strength higher than that of aluminum on the surface of the reflective electrode. A method for manufacturing a reflection type liquid crystal display device. 8. The method according to claim 7, wherein the surface protective layer is formed by anodizing the surface of the reflective electrode. 9. A method of manufacturing a reflective liquid crystal display device according to claim 7, wherein said surface protective layer is formed by forming a film made of aluminum oxide on the surface of the reflective electrode by sputtering. Method. 10. A method of manufacturing a reflective liquid crystal display device according to claim 7, wherein said surface protective layer is formed by forming a film made of silicon oxide on the surface of the reflective electrode by sputtering. Method.