JP2003228062A - Liquid crystal display device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To flatten an upper surface of an insulating layer under a rugged reflecting layer in a reflection type liquid crystal display device provided with a rugged reflecting layer on the internal surface side of a thin film transistor substrate. <P>SOLUTION: A gate electrode 38, an auxiliary capacitance line 36, and a reflecting layer 37 formed from an aluminum metal are formed at the same time on a thin film transistor substrate 31. Minute groove parts 37a are formed on the upper surface of the reflecting layer 37 by half etching. Thus, A rugged reflecting layer 37 can be obtained even if the upper surface of a thin film transistor substrate 31 under the reflecting layer 37 is flat. The reflecting layer 37 can be formed on a gate insulating film 41. Moreover, a pixel electrode 32 can be used as a reflecting layer as described above. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 14 is a partial sectional view of an example of a conventional reflection type liquid crystal display device. This liquid crystal display device includes a thin film transistor substrate 1 made of a glass substrate or the like. A scanning line (not shown) including a gate electrode 2 made of an aluminum-based metal such as aluminum or an aluminum alloy is provided at each predetermined position on the upper surface of the thin film transistor substrate 1.

A gate insulating film 3 made of silicon nitride is provided on the entire upper surface of the thin film transistor substrate 1 including the gate electrode 2 and the like. A semiconductor thin film 4 made of intrinsic amorphous silicon is provided on a portion of the upper surface of the gate insulating film 3 corresponding to the gate electrode 2. A channel protection film 5 made of silicon nitride is provided on the upper surface of the semiconductor thin film 4 substantially in the center thereof.

Ohmic contact layers 6 and 7 made of n-type amorphous silicon are provided on both upper surfaces of the channel protection film 5 and on the upper surface of the semiconductor thin film 4 on both sides thereof. A source electrode 8 made of a chromium-based metal such as chromium or a chromium alloy is provided on the upper surface of one ohmic contact layer 6. A data line (not shown) including a drain electrode 9 made of a chromium-based metal is provided at a predetermined position on the upper surface of the other ohmic contact layer 7 and the upper surface of the gate insulating film 3.

Then, the gate electrode 2, the gate insulating film 3,
A thin film transistor 10 is composed of the semiconductor thin film 4, the channel protective film 5, the ohmic contact layers 6 and 7, the source electrode 8 and the drain electrode 9.

An overcoat film 11 made of an organic material such as polyimide or acrylic resin is provided on the entire upper surface of the gate insulating film 3 including the thin film transistor 10 and the like. A contact hole 12 is provided in a portion of the overcoat film 11 corresponding to a predetermined portion of the source electrode 8. Most of the pixel electrode formation region on the upper surface of the overcoat film 11 has fine irregularities due to the formation of the fine tapered depressions 13.

In the pixel electrode formation region on the upper surface of the overcoat film 11, a pixel electrode 14 made of highly reflective aluminum-based metal is provided through the contact hole 12 and the source electrode 8 is formed.
It is connected to and provided. In this case, the pixel electrode 14
Are formed in a fine uneven shape so as to follow the fine unevenness on the upper surface of the overcoat film 11.

Here, the pixel electrode 14 is formed of a highly reflective aluminum-based metal because
This is because it has a reflection function. In addition, the pixel electrode 14
Is formed into a fine uneven shape, and has an anti-glare function (for example, a function to prevent reflection of the observer himself or the scenery behind the observer) by scattering and reflecting external light. This is because.

Next, a method of manufacturing the thin film transistor substrate 1 side of the conventional liquid crystal display device will be described. First,
As shown in FIG. 15, a gate electrode 2 made of an aluminum-based metal is provided at a predetermined position on the upper surface of the thin film transistor substrate 1.
Forming a scan line (not shown). Next, the gate insulating film 3, which is made of silicon nitride, the intrinsic amorphous silicon film 21, and the silicon nitride film are continuously formed on the entire upper surface of the thin film transistor substrate 1 including the gate electrode 2 and the silicon nitride film is patterned. ,
The channel protection film 5 is formed. Next, the natural oxide film (not shown) formed on the upper surface of the intrinsic amorphous silicon film 21 is removed using an NH4F solution.

Next, an n-type amorphous silicon film 22 is formed on the entire upper surface of the intrinsic amorphous silicon film 21 including the channel protective film 5. Next, by sequentially patterning the n-type amorphous silicon film 22 and the intrinsic amorphous silicon film 21, as shown in FIG. 16, ohmic contact layers 6 and 7 and the semiconductor thin film 4 are formed.
To form.

Next, as shown in FIG. 17, a source electrode 8 made of a chromium-based metal is formed on the upper surface of one ohmic contact layer 6. At the same time when the source electrode 8 is formed, a data line (not shown) including a drain electrode 9 made of a chromium-based metal is formed at a predetermined position on the upper surface of the other ohmic contact layer 7 and the upper surface of the gate insulating film 3. .

Next, the overcoat film 1 made of an organic material such as polyimide or acrylic resin is applied to the entire upper surface of the gate insulating film 3 including the thin film transistor 10 by a coating method.
1 is formed. Next, the contact hole 1 is formed in a portion of the overcoat film 11 corresponding to a predetermined portion of the source electrode 8.
Form 2. Next, as shown in FIG. 14, a fine tapered recess 13 is formed in most of the pixel electrode formation region on the upper surface of the overcoat film 11.

Here, a method of forming the finely tapered concave portion 13 will be described (see Japanese Patent Laid-Open No. 10-319422). First, as shown in FIG. 17, a resist film 23 is patterned on the upper surface of the overcoat film 11 including the contact holes 12. In this case, a fine convex portion 23a is formed in a portion of the resist film 23 corresponding to most of the pixel electrode formation region.

Next, heat treatment is performed to form the protrusions 23.
Take the top corner of a and round the top. Next, of the overcoat film 11 made of an organic material such as polyimide or acrylic resin, the resist film 23 including the convex portion 23a.
The part not covered with is half-etched by wet etching. Then, as shown in FIG. 14, since the upper portion of the convex portion 23a is rounded with its corners rounded, a fine tapered concave portion 13 is formed in most of the pixel electrode formation region on the upper surface of the overcoat film 11. To be done.

In this case, if the overcoat film 11 is formed by depositing an inorganic material such as silicon nitride by the CVD method, it is difficult to form the finely tapered recess 13 on the upper surface thereof. Therefore, as described above, the overcoat film 11 is formed by applying an organic material such as polyimide or acrylic resin by a coating method.

Next, the resist film 23 is peeled off. next,
As shown in FIG. 14, the pixel electrode 2 made of an aluminum-based metal is formed in the pixel electrode formation region on the upper surface of the overcoat film 11 so as to be connected to the source electrode 8 through the contact hole 12. In this case, the pixel electrode 14 is formed in a fine uneven shape following the fine unevenness of the upper surface of the overcoat film 11. Thus, the thin film transistor substrate 1 side shown in FIG. 14 is obtained.

[0017]

As described above, in the above-described conventional liquid crystal display device, the fine tapered recessed portion 13 is formed on the upper surface of the overcoat film 11 below the uneven pixel electrode 14 having a reflecting function. Overcoat film 11
Is formed by applying an organic material such as polyimide or acrylic resin by a coating method. However, the overcoat film 11 made of an organic material such as polyimide or acrylic resin applied by the coating method is less dense than an insulating film made of an inorganic material such as silicon nitride formed by the CVD method. Therefore, heat resistance when an aluminum-based metal film for forming the pixel electrode 14 is formed by a sputtering method, chemical corrosion resistance when the aluminum-based metal film is wet-etched to form the pixel electrode 14, There is a problem that the moisture resistance tends to occur. Therefore, an object of the present invention is to provide a liquid crystal display device and a method for manufacturing the same in which the upper surface of the insulating layer below the uneven reflective layer can be made substantially flat instead of fine unevenness.

[0018]

According to a first aspect of the present invention, in a liquid crystal display device in which liquid crystal is sealed between two substrates, one of the two substrates opposite to the display surface side is provided. It is characterized in that a reflective layer is provided on the inner surface side of the substrate, in which the display surface side is finely uneven and the opposite side is substantially flat. According to a second aspect of the invention, in the first aspect of the invention, a plurality of pixel electrodes are arranged in a matrix on the inner surface side of the substrate opposite to the display surface side, and the reflective layer is the display surface. It is characterized in that it is provided between the substrate on the side opposite to the side and each of the pixel electrodes. According to a third aspect of the invention, in the second aspect of the invention, an insulating film made of an inorganic material is provided between the reflective layer and the pixel electrode. According to a fourth aspect of the present invention, in the second aspect of the present invention, a switching element is connected to each of the plurality of pixel electrodes, and the reflective layer is on the same plane as any of the electrodes forming the switching element. It is characterized in that it is formed and provided of the same material as the electrode. A fifth aspect of the invention is characterized in that, in the first aspect of the invention, a plurality of pixel electrodes arranged in a matrix are formed by the reflective layer. According to a sixth aspect of the present invention, in the fifth aspect, the pixel electrode is provided on an insulating film made of an inorganic material. According to a seventh aspect of the present invention, in a method of manufacturing a liquid crystal display device in which a liquid crystal is sealed between two substrates, a display is provided on an inner surface side of the substrate opposite to the display surface side of the two substrates. Form a reflective layer whose surface side and the opposite side are almost flat,
It is characterized in that fine concave portions are formed on the display surface side of the reflective layer by anisotropic etching. The invention according to claim 8 is the invention according to claim 7, wherein the reflective layer is formed so as to correspond to a plurality of pixel electrodes formed in a matrix on the display surface side thereof. It is what A ninth aspect of the present invention is characterized in that, in the eighth aspect, an insulating film made of an inorganic material is formed on the reflective layer, and the pixel electrode is formed thereon. . The invention according to claim 10 is the invention according to claim 8, wherein the reflective layer comprises:
It is characterized in that it is formed of the same material as the electrodes at the same time as the formation of any of the electrodes constituting the switching element connected to each of the plurality of pixel electrodes. An eleventh aspect of the invention is characterized in that, in the tenth aspect of the invention, an anodic oxide film is formed on the surface of the electrode formed at the same time as the reflective layer. According to a twelfth aspect of the invention, in the seventh aspect of the invention, the reflective layer forms a plurality of pixel electrodes arranged in a matrix. According to a thirteenth aspect of the present invention, in the twelfth aspect of the present invention, the pixel electrode is formed on an insulating film made of an inorganic material. According to a fourteenth aspect of the present invention, in the invention according to the seventh aspect, the anisotropic etching is half etching using a working liquid. According to a fifteenth aspect of the invention, in the invention according to the seventh aspect, the reflective layer is formed of an aluminum-based metal. According to a sixteenth aspect of the invention, in the fifteenth aspect of the invention, the anisotropic etching is half etching using a hydrofluoric acid solution. The invention according to claim 17 is the invention according to claim 16, characterized in that the hydrofluoric acid-based solution is an NH 4 F solution. Further, according to the present invention, since the display surface side of the reflection layer which is substantially flat on the side opposite to the display surface is made finely uneven, it is not necessary to make the upper surface of the insulating layer below the uneven reflection layer finely uneven. Therefore, the upper surface of the insulating layer below the uneven reflective layer can be made substantially flat.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a sectional view of a main part of a liquid crystal display device according to a first embodiment of the present invention, and FIG. It is the transmission top view of the part. However, in this case, FIG. 1 is a sectional view corresponding to a portion along the line AA in FIG.

This liquid crystal display device is provided with a thin film transistor substrate 31 and a counter substrate 51 made of a glass substrate or the like. On the upper surface side of the thin film transistor substrate 31, a plurality of pixel electrodes 32 arranged in a matrix, and a plurality of thin film transistors 33 respectively connected to these pixel electrodes 32 are arranged in the row direction.
3, a plurality of scan lines 34 for supplying a scan signal to 3 and a plurality of data lines 35 arranged in the column direction, and a plurality of data lines 35 for supplying a data signal to the thin film transistor 33, arranged in the row direction,
A plurality of auxiliary capacitance lines 36 forming an auxiliary capacitance portion at a portion overlapping with each pixel electrode 32, and a plurality of reflective layers 37 arranged at positions overlapping with substantially the central portion of each pixel electrode 32 are provided. .

That is, the scanning line 34 including the gate electrode 38 made of a highly reflective aluminum-based metal, the auxiliary capacitance line 36, and the reflective layer 37 are provided at predetermined positions on the upper surface of the thin film transistor substrate 31. In this case, the anodic oxide film 3 is formed on the surface of the scanning line 34 including the gate electrode 38 and the surface of the auxiliary capacitance line 36, respectively.
9 and 40 are provided, but no anodic oxide film is provided on the surface of the reflective layer 37. In addition, the upper surface of the reflective layer 37 has a fine concave-convex shape due to the formation of the fine concave portions 37a.

A gate insulating film 41 made of silicon nitride is provided on the entire upper surface of the thin film transistor substrate 31 including the gate electrode 38 and the like. A semiconductor thin film 42 made of intrinsic amorphous silicon is provided on a portion of the upper surface of the gate insulating film 41 corresponding to the gate electrode 38. A channel protective film 43 made of silicon nitride is provided on the upper surface of the semiconductor thin film 42 at approximately the center thereof.

Ohmic contact layers 44 and 45 made of n-type amorphous silicon are formed on both upper surfaces of the channel protection film 43 and on the upper surfaces of the semiconductor thin film 42 on both sides thereof.
Is provided. One ohmic contact layer 44
A source electrode 46 made of a chromium-based metal is provided on the upper surface of the. The data line 3 including a drain electrode 47 made of a chromium-based metal is provided at a predetermined position on the upper surface of the other ohmic contact layer 45 and the upper surface of the gate insulating film 41.
5 are provided.

Then, the gate electrode 38 and the anodic oxide film 3 are formed.
A thin film transistor 33 is constituted by 9, the gate insulating film 41, the semiconductor thin film 42, the channel protective film 43, the ohmic contact layers 44 and 45, the source electrode 46 and the drain electrode 47.

An overcoat film 48 made of silicon nitride is provided on the entire upper surface of the gate insulating film 41 including the thin film transistors 33 and the like. Overcoat film 48
A contact hole 49 is provided in a portion of the source electrode 46 corresponding to a predetermined position. A pixel electrode 32 made of ITO is provided on the overcoat film 48 so as to cover the entire reflective layer 37, and the pixel electrode 32 is connected to the source electrode 46 via a contact hole 49. An alignment film 50 is provided on the upper surface of the overcoat film 48 including the pixel electrodes 32.

On the other hand, a black mask 52 and red, green and blue color filters 53 are provided on the lower surface of the counter substrate 51, a counter electrode 54 is provided on the lower surface thereof, and an alignment film 55 is provided on the lower surface thereof. ing. Then, the thin film transistor substrate 31 and the counter substrate 51 are attached to each other via a sealing material (not shown). In addition, the alignment films 50 and 55 of both substrates 31 and 51 inside the sealing material
A liquid crystal 56 is enclosed between them. In FIG. 2, the area surrounded by the dashed-dotted line which is smaller than the reflective layer 37 is the opening 52 a of the black mask 52.

As described above, in this liquid crystal display device, the reflective layer 37 is provided below the central portion of the pixel electrode 32 via the overcoat film 48 and the gate insulating film 41, and as shown in FIG. Is smaller than the pixel electrode 32 and larger than the opening 52a of the black mask 52. In this case, it is desirable that the reflective layer 37 be as large as possible. Therefore, in FIG. 2, the upper side of the reflective layer 37 is brought as close as possible to the auxiliary capacitance line 36, the left and right sides are aligned with or outside the left and right sides of the pixel electrode 32, and the lower side is placed as close as possible to the scanning line 34. You may make it close to each other.

In this reflection type liquid crystal display device,
External light incident from the upper surface side (display surface side) of the counter substrate 51, the counter substrate 51, the color filter 53, the counter electrode 54,
The light is transmitted through the alignment film 55, the liquid crystal 56, the alignment film 50, the pixel electrode 32, and the both insulating films 48 and 41, and is scattered and reflected by the fine uneven surface of the reflection layer 37. After that, the light is emitted to the upper surface side of the counter substrate 51, so that display is performed.

Next, an example of a method of manufacturing the thin film transistor substrate 31 side of the liquid crystal display device shown in FIGS. 1 and 2 will be described. First, as shown in FIG. 3, an aluminum-based metal film is formed on the entire upper surface of the thin film transistor substrate 31 by a sputtering method, and the aluminum-based metal film is patterned by a photolithography method, so that the scanning line 34 including the gate electrode 38 is formed. , The auxiliary capacitance line 36 and the reflective layer 37 are formed. In the patterning in this case, since the scanning line 34 including the gate electrode 38 and the auxiliary capacitance line 36 are anodized in the next step, they are electrically connected by wiring, and the reflection layer 37 is not connected to any wiring. It is formed into an electrically isolated island.

In this state, the lower surface of the reflective layer 37 is flat following the flat upper surface of the thin film transistor substrate 31, and the upper surface is also substantially flat. In this case, the reflective layer 3
7 at the same time when the gate electrode 38 and the like are formed.
Since it is formed of the same material as 8 or the like, that is, a highly reflective aluminum-based metal film, the number of processes does not increase.

Next, an anodic oxidation process is performed to form anodic oxide films 39 and 40 on the surface of the scanning line 34 including the gate electrode 38 and the surface of the auxiliary capacitance line 36, respectively. In this case, since the reflective layer 37 has an island shape, the anodizing current is not supplied to the reflective layer 37, and thus the anodized film is not formed on the surface of the reflective layer 37. As described above, if the patterning is performed before the anodizing treatment, the anodizing treatment can be performed without forming the resist film on the reflection layer 37 which is the non-anodizing portion, and the number of processes does not increase. .

Next, as shown in FIG. 4, the anodic oxide film 3 is formed.
A resist film 61 is patterned on the upper surface of the thin film transistor substrate 31 including 9, 40 and the like. In this case, an opening 62 is formed in the portion of the resist film 61 corresponding to the reflective layer 37. Next, when half etching is performed using a hydrofluoric acid solution such as NH4F solution, as shown in FIG. 5, fine recesses 37a are formed on the upper surface of the reflective layer 37.

Here, considering the formation of the fine recesses 37a, firstly, for example, the aluminum alloy film is in a polycrystalline state, and the etching with the NH4F solution to this aluminum alloy film is anisotropic. The etch rate differs depending on the crystal orientation of the alloy film. Secondly, since the impurities are segregated in the crystal grain boundaries of the aluminum alloy film, the etching rate of the crystal grain boundaries of the aluminum alloy film is higher than that in other portions. From the above two points, it is considered that when half etching is performed using the NH4F solution, fine recesses 37a are formed on the upper surface of the reflective layer 37.

Next, the resist film 61 is peeled off. next,
As shown in FIG. 6, a gate insulating film 41 made of silicon nitride, an intrinsic amorphous silicon film 63, and a silicon nitride film are continuously formed by a CVD method on the entire upper surface of the thin film transistor substrate 31 including the gate electrode 38 and the like. The channel protection film 43 is formed by patterning the silicon film by photolithography. Next, the natural oxide film (not shown) formed on the upper surface of the intrinsic amorphous silicon film 31 is removed using an NH4F solution.

Next, the entire upper surface of the intrinsic amorphous silicon film 63 including the channel protective film 43 is n-doped by the CVD method.
A type amorphous silicon film 64 is formed. Next, the n-type amorphous silicon film 64 and the intrinsic amorphous silicon film 63 are continuously patterned by a photolithography method to form ohmic contact layers 44 and 45 and a semiconductor thin film 42 as shown in FIG.

Next, as shown in FIG. 8, the semiconductor thin film 42.
A chromium-based metal film is formed on the entire upper surface of the gate insulating film 41 including the ohmic contact layers 44 and 45 by the sputtering method, and the chromium-based metal film is patterned by the photolithography method. Forming a data line 35 including

Next, an overcoat film 48 made of silicon nitride is formed on the entire upper surface of the gate insulating film 41 including the thin film transistor 33 and the like by the CVD method. Next, a contact hole 49 is formed in the portion of the overcoat film 48 corresponding to a predetermined portion of the source electrode 46 by photolithography.

Next, as shown in FIG. 1, an ITO film is formed on the entire upper surface of the overcoat film 48 including the inside of the contact hole 49 by a sputtering method, and the ITO film is patterned by a photolithography method to form a pixel. The electrode 32 is connected to the source electrode 46 through the contact hole 49.
It is formed by connecting to. Next, the alignment film 50 is formed on the upper surface of the overcoat film 48 including the pixel electrodes 32. Thus, the thin film transistor substrate 31 side shown in FIG. 1 is obtained.

As described above, according to this manufacturing method, since the reflective layer 37 having the fine concave portions 37a on the upper surface is formed on the thin film transistor substrate 31 by the highly reflective aluminum-based metal, the layer below the reflective layer 37 is formed. It is not necessary to form fine recesses on the upper surface of the thin film transistor substrate 31. Further, since the pixel electrode 32 made of ITO does not have a reflection function, it is not necessary to form a fine uneven shape, and therefore it is not necessary to form a fine concave portion on the upper surface of the overcoat film 48 thereunder. As a result, even if the overcoat film 48 is formed by depositing an inorganic material such as silicon nitride by the CVD method, there is no problem, and the heat resistance, chemical erosion resistance, and moisture resistance of the overcoat film 48 are improved. can do.

(Second Embodiment) FIG. 9 shows a thin film transistor substrate 3 of a liquid crystal display device according to a second embodiment of the present invention.
1 is a cross-sectional view of the side 1 similar to FIG. 1. This liquid crystal display device is different from the case shown in FIG. 1 in that the reflective layer 37 is provided on the gate insulating film 41, not on the thin film transistor substrate 31.

Next, a part of an example of a method of manufacturing the thin film transistor substrate 31 side of this liquid crystal display device will be described. In this case, of course, in the state shown in FIG. 7, the reflective layer 37 is not formed on the thin film transistor substrate 31. Then, in the state shown in FIG. 7, the semiconductor thin film 42 and the ohmic contact layers 44, 45.
As shown in FIG. 10, the source electrode 46 and the drain electrode 47 are formed by forming an aluminum-based metal film on the entire upper surface of the gate insulating film 41 including the film by sputtering and patterning the aluminum-based metal film by photolithography. Etc. are formed, and at the same time as the formation, the reflective layer 37 is formed at a predetermined position on the upper surface of the gate insulating film 41. In the patterning, the reflection layer 37 is formed by the source electrode 46,
Also, the electrodes are formed in an electrically isolated island shape so as not to be connected to any wiring such as the data line 35 including the drain electrode 47.

In this state, the lower surface of the reflecting layer 37 is substantially flat following the substantially flat upper surface of the gate insulating film 41, and the upper surface is also substantially flat. In this case, the reflective layer 3
Since 7 is formed of the same material as the source electrode 46, the drain electrode 47, etc., that is, the highly reflective aluminum-based metal film at the same time as the formation of the source electrode 46, the drain electrode 47, etc., the number of processes does not increase.

Next, as shown in FIG. 11, a resist film 71 is patterned on the upper surface of the gate insulating film 41 including the thin film transistors 33 and the data lines 35. In this case, an opening 72 is formed in the portion of the resist film 71 corresponding to the reflective layer 37. Next, when half etching is performed using a hydrofluoric acid-based solution such as NH4F solution,
A fine recess 37 a is formed on the upper surface of the reflective layer 37. Next, the resist film 71 is peeled off.

Next, as shown in FIG. 9, CVD is performed on the entire upper surface of the gate insulating film 41 including the thin film transistor 33 and the like.
An overcoat film 48 made of silicon nitride is formed by a method. Next, the source electrode 4 of the overcoat film 48
A contact hole 49 is formed in a portion corresponding to a predetermined portion of 6 by photolithography.

Next, ITO is formed on the entire upper surface of the overcoat film 48 including the inside of the contact hole 49 by sputtering.
A film is formed and the ITO film is patterned by a photolithography method, so that the pixel electrode 32 is formed so as to be connected to the source electrode 46 through the contact hole 49. Next, the alignment film 50 is formed on the upper surface of the overcoat film 48 including the pixel electrodes 32. Thus, the thin film transistor substrate 31 side shown in FIG. 9 is obtained.

As described above, in this manufacturing method, the highly reflective aluminum-based metal is formed on the gate insulating film 41.
Since the reflective layer 37 having the fine recesses 37a is formed on the upper surface, it is not necessary to form the fine recesses on the upper surface of the gate insulating film 41 below the reflective layer 37. Further, since the pixel electrode 32 made of ITO does not have a reflection function, it is not necessary to form a fine uneven shape, and therefore it is not necessary to form a fine concave portion on the upper surface of the overcoat film 48 thereunder. As a result, also in this case, there is no problem even if the overcoat film 48 is formed by depositing an inorganic material such as silicon nitride by the CVD method, and the heat resistance and chemical erosion resistance of the overcoat film 48, Moisture resistance can be improved.

(Third Embodiment) FIG. 12 shows a third embodiment of the present invention.
1 is a cross-sectional view similar to FIG. 1 on a thin film transistor substrate 31 side of a liquid crystal display device as an embodiment. This liquid crystal display device is different from the case shown in FIG. 1 in that the pixel electrode 32 has a function as a reflection plate.

Next, a part of an example of a method of manufacturing the liquid crystal display device on the thin film transistor substrate 31 side will be described. In this case, of course, in the state shown in FIG. 8, the reflective layer 37 is not formed on the thin film transistor substrate 31. Then, in the state shown in FIG. 8, an aluminum-based metal film is formed on the entire upper surface of the overcoat film 48 including the inside of the contact hole 49 by a sputtering method, and the aluminum-based metal film is patterned by a photolithography method. As shown in 13,
The pixel electrode 32 is formed by being connected to the source electrode 46 via the contact hole 49.

In this state, the lower surface of the pixel electrode 32 is substantially flat following the substantially flat upper surface of the gate insulating film 41, and the upper surface is also substantially flat. Further, in this case, since the pixel electrode 32 is only formed of the highly reflective aluminum-based metal film, the number of processes does not increase.

Next, half etching is performed using a hydrofluoric acid solution such as NH4F solution to form fine recesses 32a on the upper surface of the pixel electrode 32, as shown in FIG. Next, the alignment film 50 is formed on the upper surface of the overcoat film 48 including the pixel electrodes 32. Thus, the thin film transistor substrate 31 side shown in FIG. 12 is obtained.

As described above, in this manufacturing method, since the pixel electrode 32 having the fine concave portions 32a on the upper surface is formed on the overcoat film 48 by the highly reflective aluminum-based metal, the pixel electrode 32 is formed below the pixel electrode 32. Overcoat film 4
It is not necessary to form fine recesses on the upper surface of 8. Therefore,
Also in this case, there is no problem even if the overcoat film 48 is formed by depositing an inorganic material such as silicon nitride by the CVD method, and the heat resistance of the overcoat film 48 is
Chemical corrosion resistance and moisture resistance can be improved. Also,
Since no resist film is used when forming the minute recesses 32a on the upper surface of the pixel electrode 32, the number of manufacturing steps can be reduced as compared with the case of the first and second embodiments.

(Other Embodiments) In each of the above embodiments, the channel protection type amorphous silicon thin film transistor has been described. However, the present invention is not limited to this. May be Further, it can be applied to a liquid crystal display device using a non-linear element such as MIM as a switching element in addition to a thin film transistor. Further, the present invention can be applied not only to a liquid crystal display device using a switching element but also to a simple matrix liquid crystal display device and the like.

[0053]

As described above, according to the present invention, since the display surface side of the reflection layer which is substantially flat on the side opposite to the display surface is made finely uneven, the upper surface of the insulating layer below the uneven reflection layer. Does not need to be finely uneven, and therefore the upper surface of the insulating layer below the uneven reflecting layer can be made substantially flat. As a result, the insulating film (overcoat film) under the pixel electrode can be formed of an inorganic material such as silicon nitride, and the heat resistance and chemical erosion resistance of the insulating film under the pixel electrode can be reduced.
Moisture resistance can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a liquid crystal display device as a first embodiment of the present invention.

FIG. 2 is a transparent plan view of the thin film transistor substrate side of the liquid crystal display device shown in FIG.

FIG. 3 is a cross-sectional view of an initial manufacturing process in manufacturing the thin film transistor substrate side of the liquid crystal display device shown in FIGS. 1 and 2.

FIG. 4 is a cross-sectional view of the manufacturing process following FIG.

FIG. 5 is a cross-sectional view of the manufacturing process following FIG.

FIG. 6 is a cross-sectional view of the manufacturing process following FIG.

FIG. 7 is a cross-sectional view of the manufacturing process following FIG.

FIG. 8 is a cross-sectional view of the manufacturing process following FIG.

FIG. 9 is a cross-sectional view similar to FIG. 1 on a thin film transistor substrate side of a liquid crystal display device according to a second embodiment of the present invention.

10 is a cross-sectional view of a predetermined manufacturing process in manufacturing the thin film transistor substrate side shown in FIG.

FIG. 11 is a cross-sectional view of the manufacturing process following FIG.

FIG. 12 is a sectional view similar to FIG. 1 on a thin film transistor substrate side of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 13 is a transparent plan view of a thin film transistor substrate side of a conventional liquid crystal display device.

14 is a cross-sectional view of an initial manufacturing process in manufacturing the thin film transistor substrate side shown in FIG.

FIG. 15 is a cross-sectional view of the manufacturing process following FIG.

16 is a cross-sectional view of the manufacturing process following FIG.

FIG. 17 is a cross-sectional view of the manufacturing process following FIG.

[Explanation of symbols]

31 thin film transistor substrate 32 pixel electrodes 32a recess 33 thin film transistor 37 Reflective layer 37a recess 38 Gate electrode 41 Gate insulation film 46 source electrode 47 drain electrode 48 Overcoat film 51 Counter substrate 56 LCD

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Claims (17)

[Claims] 1. A liquid crystal display device in which a liquid crystal is sealed between two substrates, wherein the display surface side has fine irregularities on the inner surface side of the substrate opposite to the display surface side. A liquid crystal display device characterized in that a reflection layer having a substantially flat surface on the opposite side is provided. 2. The invention according to claim 1, wherein a plurality of pixel electrodes are arranged in a matrix on the inner surface side of the substrate opposite to the display surface side, and the reflective layer is opposite to the display surface side. A liquid crystal display device, wherein the liquid crystal display device is provided between the substrate on the side and each of the pixel electrodes. 3. The liquid crystal display device according to claim 2, wherein an insulating film made of an inorganic material is provided between the reflective layer and the pixel electrode. 4. The invention according to claim 2, wherein a switching element is connected to each of the plurality of pixel electrodes,
The liquid crystal display device, wherein the reflective layer is formed and provided on the same plane as any of the electrodes forming the switching element by using the same material as the electrode. 5. The liquid crystal display device according to claim 1, wherein a plurality of pixel electrodes arranged in a matrix are formed by the reflective layer. 6. The liquid crystal display device according to claim 5, wherein the pixel electrode is provided on an insulating film made of an inorganic material. 7. A method of manufacturing a liquid crystal display device in which liquid crystal is sealed between two substrates, wherein a display surface side and an inner surface side of the substrate opposite to the display surface side of the two substrates are provided. A method for manufacturing a liquid crystal display device, characterized in that a reflective layer having a substantially flat surface on the opposite side is formed, and fine recesses are formed on the display surface side of the reflective layer by anisotropic etching. 8. The liquid crystal display according to claim 7, wherein the reflective layer is formed so as to correspond to a plurality of pixel electrodes formed in a matrix on the display surface side thereof. Device manufacturing method. 9. The method for manufacturing a liquid crystal display device according to claim 8, wherein an insulating film made of an inorganic material is formed on the reflective layer, and the pixel electrode is formed thereon. 10. The invention according to claim 8, wherein the reflective layer is formed of the same material as the electrodes at the same time when any of the electrodes constituting the switching elements connected to the plurality of pixel electrodes is formed. A method for manufacturing a liquid crystal display device, comprising: 11. The method of manufacturing a liquid crystal display device according to claim 10, wherein an anodic oxide film is formed on a surface of the electrode formed simultaneously with the reflective layer. 12. The method for manufacturing a liquid crystal display device according to claim 7, wherein the reflective layer forms a plurality of pixel electrodes arranged in a matrix. 13. The method of manufacturing a liquid crystal display device according to claim 12, wherein the pixel electrode is formed on an insulating film made of an inorganic material. 14. The method of manufacturing a liquid crystal display device according to claim 7, wherein the anisotropic etching is half etching using a working liquid. 15. The method of manufacturing a liquid crystal display device according to claim 7, wherein the reflective layer is formed of an aluminum-based metal. 16. The method of manufacturing a liquid crystal display device according to claim 15, wherein the anisotropic etching is half etching using a hydrofluoric acid solution. 17. The method for manufacturing a liquid crystal display device according to claim 16, wherein the hydrofluoric acid solution is an NH4F solution.