JP2001330827A - Reflective liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize cost reduction and improvement in productivity and to provide a structure in which disconnection, formation of large parasitic capacitance between wiring and pixels and destruction of an insulation film accompanying projecting and recessing pattern formation are prevented by making the projecting and recessing pattern of a reflection electrode in a TFT(thin film transistor) array substrate of a reflective liquid crystal display device capable of being formed via a simplified process. SOLUTION: Groups of wiring, TFTs, auxiliary capacitance parts and a reflection electrode 15 formed on a recessing pattern 14b exist on a principal surface of the substrate 1. A projecting and recessing pattern is constructed by using a recessing pattern formed with openings on an insulation film 3 simultaneously deposited with an insulation film composing the TFTs. The projecting and recessing pattern is arranged so as not to intersect the groups of wiring, the TFTs or the auxiliary capacitance parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection type liquid crystal display device driven by a thin film transistor, and more particularly to a reflection type liquid crystal display device having a reflection electrode formed on an uneven pattern.

[0002]

2. Description of the Related Art The structure of a conventional reflection type liquid crystal display device will be described with reference to FIGS. Figures 8 and 9
FIG. 3 is a cross-sectional view showing a manufacturing process of a thin film transistor (hereinafter, referred to as TFT) array substrate in a conventional reflective liquid crystal display device. 8 (a) to 8 (d) and FIG.
(E)-(g) show a series of steps.

In a conventional manufacturing process of a TFT array substrate, first, as shown in FIG.
The gate wiring 2 is formed using a metal such as aluminum or chromium. The gate wiring 2 extends in the row direction. Next, as shown in FIG. 8B, a silicon nitride film 3 functioning as a gate insulating film, a semiconductor film 4 whose resistivity changes depending on the potential of the gate electrode, and a TFT functioning as a switch, and a semiconductor film 4 and a source. Then, an n + semiconductor film 5 for making ohmic contact with the drain electrode is continuously deposited, and a pattern composed of the semiconductor film 4 and the n + semiconductor film 5 is formed in the TFT portion. Next, as shown in FIG. 8C, a source electrode 6a and a drain electrode 6b are formed using a conductive film such as titanium or aluminum. The wiring connected to the source electrode 6a extends in the column direction. At this time, the source electrode 6
a, the source electrode 6a using the drain electrode 6b as a mask.
The n + semiconductor film 5 existing between the gate electrode and the drain electrode 6b and a part of the semiconductor film 4 are removed by etching.

Next, as shown in FIG. 8D, a silicon nitride film 7 functioning as an insulating protective film is deposited, and a hole 8a is formed in the silicon nitride film 7 on the drain electrode 6b. Next, as shown in FIG. 9E, after a first planarizing film 9 made of a photosensitive resin is applied, the opening 1 is formed at the same position as the opening 8a of the silicon nitride film 7 by a photolithography process.
0 is formed. At this time, in order to diffuse light reflected on the pixel electrode, a concave portion 11 is formed on the flattening film 9 at a position below the pixel electrode. Next, as shown in FIG. 9F, after a second planarizing film 12 made of a photosensitive resin is applied, the same position as the opening 10 on the first planarizing film 9 is formed by a photolithography process. An opening 13 is formed in the opening. At this time, the concave portion 11 previously formed on the first flattening film 9 is filled with the opening by the second flattening film 12, and becomes a concave portion 14 having a somewhat smooth shape, thereby obtaining a desired diffusion effect. be able to. Finally, as shown in FIG. 9G, a pixel electrode 15 made of aluminum or the like having a high reflectance is formed. The pixel electrode 15 is connected to the drain electrode 6 b through the opening 13 formed on the first and second planarization films 9 and 12 and the opening 10 formed on the silicon nitride film 7. Also,
The pixel electrode 15 overlaps the previous gate wiring 2 via an interlayer insulating film, and forms a capacitance with the gate wiring 2. This capacity is called an auxiliary capacity. Then, the pixel electrode 15 has
A signal is input from a source wiring connected to the source electrode 6a through a TFT serving as a switch.

[0005]

According to the above-mentioned conventional method for manufacturing a TFT array substrate of a reflection type liquid crystal display device, seven photolithography steps are required. Among them, in order to form unevenness having a desired shape for diffusing light, two steps of application of a flattening film and two steps of photolithography are required. The material cost of the flattening film is very expensive, and the photosensitivity of the flattening film is lower than that of a normal resist material, and is 2-3 times smaller than that of normal photolithography.
Since the double exposure time is required, there is a problem that the processing capability of the exposure apparatus is significantly reduced.

Furthermore, as described in Japanese Patent Application Laid-Open No. 9-54318, in order to simplify the process, when forming the unevenness of the reflector in the same process at the time of manufacturing the TFT,
Since the concavo-convex pattern of the reflector is formed in the same layer as the TFT, the wiring, and the auxiliary capacitance portion, the pattern may cause a defect such as disconnection. Also, T
Dust generated during photolithography and etching for forming the FT may cause a short circuit between the wiring and the concave / convex pattern of the reflector. In particular, when the concavo-convex pattern is one large pattern, a large parasitic capacitance is formed between the wiring and the pixel, and the pixel potential is coupled to the wiring signal and fluctuates from the normal pixel potential. In some cases, there is also a problem that the probability of reaching a point defect increases due to short-circuiting due to breakdown of the insulating film or the like.

[0007]

In order to solve the above-mentioned problems, a reflection type liquid crystal display device of the present invention comprises a wiring group, a thin film transistor, an auxiliary capacitance portion, and an uneven pattern on one main surface of a substrate. A concavo-convex pattern is formed using a concave portion formed by opening an insulating film formed simultaneously with the insulating film forming the thin-film transistor, and the concavo-convex pattern includes a wiring group, a thin-film transistor , Or so as not to intersect with the auxiliary capacitance section.

According to this structure, the number of steps of applying a flattening film for forming a concavo-convex pattern and performing photolithography can be reduced, so that significant cost reduction and improvement in productivity can be realized. In addition, in the etching step of opening the insulating film, it is possible to prevent the insulating film located below the wiring or the glass substrate from being etched at the same time due to a part of the opening straddling over the wiring. Therefore,
As a result, the problem that the wiring is cut off, the wiring resistance increases, and the probability of disconnection is increased is eliminated.

A reflection type liquid crystal display device having another configuration of the present invention has a wiring group, a thin film transistor, an auxiliary capacitance portion, and a reflection electrode formed on an uneven pattern on one main surface of a substrate. The concavo-convex pattern is formed using a plurality of island-shaped patterns made of the semiconductor or the conductor, which are formed simultaneously with the semiconductor or the conductor constituting the thin film transistor.

According to this structure, since the semiconductor or the conductive convex pattern is formed by a plurality of islands, even if conductive dust or an unnecessary pattern exists between the convex pattern and the wiring, the semiconductor or the conductive convex pattern is formed. Even if the unnecessary pattern and the convex pattern are short-circuited, since the convex pattern is separated,
If the dust is small, the increase in the capacitance value between the pixel and the wiring is small, and the signal on the wiring hardly affects the potential of the pixel. As a result, the probability of dust generating point defects is reduced.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 A reflection type liquid crystal display device according to Embodiment 1 of the present invention will be described with reference to FIGS. FIGS. 1 to 3 are plan views showing steps of manufacturing a TFT array substrate for driving a reflection type liquid crystal display device.
And 5 are views showing cross sections in the respective drawings of the same manufacturing process. That is, FIGS. 1A, 1B, 2C,
(D), FIGS. 3 (e) and 3 (f) show a series of steps, and FIGS. 4 (a) to 4 (d) and FIGS. 5 (e) and 5 (f) show cross sections in the respective steps. .

First, as shown in FIGS. 1A and 4A, a gate wiring 2 is formed on a glass substrate 1 using a metal such as aluminum or chromium. The gate wiring 2 extends in the row direction. Next, as shown in FIGS. 1 (b) and 4 (b), a silicon nitride film 3 functioning as a gate insulating film, and a semiconductor film 4 whose resistivity changes depending on the potential of the gate electrode to make the TFT function as a switch. And an n + semiconductor film 5 for making ohmic contact between the semiconductor film 4 and the source and drain electrodes is continuously deposited,
A pattern composed of the semiconductor film 4 and the n + semiconductor film 5 is formed in the T portion. Next, as shown in FIG. 2C and FIG. 4C, the source electrode 6a and the drain electrode 6b are formed of a conductive film such as titanium or aluminum. Source electrode 6
The wiring connected to a is extended in the column direction. At this time, using the source electrode 6a and the drain electrode 6b as a mask, the n + semiconductor film 5 existing between the source electrode 6a and the drain electrode 6b and a part of the semiconductor film 4 are removed by etching.

Next, as shown in FIGS. 2D and 4D, a silicon nitride film 7 functioning as an insulating protective film is deposited, and an opening 8a is opened in the silicon nitride film 7 on the drain electrode 6b. At this time, in order to diffuse the light reflected on the pixel electrode, a concave pattern 8b is formed in the silicon nitride films 7 and 3 below the pixel electrode. Next, FIG.
As shown in FIG. 5E and FIG. 5E, after a first planarizing film 9 made of a photosensitive resin is applied, an opening is formed at the same position as the opening 8a of the silicon nitride film 7 by a photolithography process. The part 10 is formed. At this time, the opening of the concave pattern 8b previously formed in the silicon nitride film 7 is filled with the first planarizing film 9, and the concave pattern 14b has a somewhat smooth shape, so that a desired diffusion effect can be obtained. it can. Finally, as shown in FIG. 3 (f) and FIG. 5 (f),
Pixel electrode 1 made of aluminum or the like and having a reflection function
5 is formed.

According to the present embodiment, in the manufacturing process of the TFT array substrate, the photolithography process is performed six times. Among them, the recess can be formed by one application of the flattening film and one photolithography process.
Therefore, in the conventional process, seven photolithography processes are required. In this process, two flattening films are applied and two times in order to form a concave portion having a desired shape for diffusing light. As compared with the case where the photolithography process is required, a large cost reduction and an improvement in productivity can be realized.

Further, since the opening on the insulating film serving as the concave portion is arranged above the gate wiring or between the TFT and the source wiring, there is a possibility that the insulating film below the wiring or the TFT is etched. As a result, the probability of occurrence of a defect that leads to an increase in wiring resistance due to chipping of wiring or a disconnection decreases. (Embodiment 2) Embodiment 2 will be described with reference to FIG. FIG. 6 is a diagram showing a T driving the reflection type liquid crystal display device of the present invention.
It is a completed plan view of an FT array substrate. The structure of this embodiment is manufactured by the same steps as in the first embodiment.
However, when the semiconductor pattern is formed, an island-shaped convex pattern 16 functioning as a reflection diffusion structure is formed at the same time.

With this configuration, similar to the first embodiment,
One coating of the flattening film and one photolithography process can create irregularities, resulting in significant cost reduction and
The effect of improving productivity is obtained.

Further, since the semiconductor or conductive convex pattern 16 is formed in a plurality of patterns by using this structure, even if conductive dust or unnecessary pattern is formed between the convex pattern 16 and the wiring. Exists, even if the pattern and the convex pattern 16 are short-circuited, the convex pattern 16 is separated into many islands. Therefore, if the dust is small, the increase in the capacitance value between the pixel and the wiring is small.
Therefore, there is an effect that the signal of the wiring hardly affects the potential of the pixel, and the probability that dust generates a point defect is reduced.

In the present embodiment, the plurality of island-shaped convex patterns 16 are formed of a semiconductor pattern, but may be formed of the same material as the gate wiring or the same material as the source wiring. It is possible. It is also possible to form a combination of a plurality of these three materials. The plurality of projections of different materials may be arranged at the same position or at different positions. (Embodiment 3) Embodiment 3 will be described with reference to FIG. FIG. 7 is a diagram showing a T driving the reflection type liquid crystal display device of the present invention.
It is a completed plan view of an FT array substrate. The structure of this embodiment is manufactured by the same steps as in the first embodiment.

That is, when the insulating film is opened, the concave pattern 8b composed of an opening functioning as a reflection diffusion structure is formed.
It is formed under the pixel electrode at the same position as in the first embodiment. Further, at the time of forming the semiconductor pattern, an island-shaped convex pattern 16 simultaneously functioning as a reflection diffusion structure is formed under the pixel electrode at the same position as in the second embodiment. The arrangement positions of the concave pattern 8b and the convex pattern 16 are made different. This allows
An uneven step for diffusion can be formed higher. Therefore, a reflective liquid crystal display device having a higher diffusion function can be obtained.

By using this configuration, the same effects as those of the first and second embodiments can be naturally obtained.

[0022]

According to the present invention, the manufacturing cost is very high, the process of applying a flattening film with low productivity and the process of exposing are reduced from twice to one, and the pixel electrode having a reflection diffusion effect. It can be manufactured without increasing disconnection and point defect failure due to formation of lower unevenness.

[Brief description of the drawings]

FIG. 1 is a reflective TFT according to a first embodiment of the present invention.
Plan view showing manufacturing process of array substrate

FIG. 2 is a reflective TFT according to the first embodiment of the present invention.
Plan view showing manufacturing process of array substrate

FIG. 3 is a reflective TFT according to the first embodiment of the present invention.
Plan view showing manufacturing process of array substrate

FIG. 4 is a reflective TFT according to the first embodiment of the present invention.
Sectional drawing which shows the manufacturing process of an array substrate

FIG. 5 is a reflective TFT according to the first embodiment of the present invention.
Sectional drawing which shows the manufacturing process of an array substrate

FIG. 6 shows a reflective TFT according to a second embodiment of the present invention.
Plan view of array substrate

FIG. 7 is a reflective TFT according to Embodiment 3 of the present invention.
Plan view of array substrate

FIG. 8 is a sectional view showing a manufacturing process of a conventional reflective TFT array substrate.

FIG. 9 is a sectional view showing a manufacturing process of a conventional reflective TFT array substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Gate wiring 3 Silicon nitride film 4 Semiconductor film 6a Source wiring 6b Drain electrode 7 Silicon nitride film 8a Opening 8b Concave pattern 9 First planarizing film 10 Opening 11 Concave 12 Second planarizing film 13 Opening Part 14, 14b Concave part 15 Pixel electrode 16 Convex pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H090 HA04 HA05 HB02X HB03X HC05 HC12 HD03 HD06 LA04 2H091 FA14Y FA31Y FC26 FD04 GA02 GA07 GA13 LA02 LA12 LA16 2H092 JA28 JA34 JA41 JA47 JB07 JB08 JB22 JB57 KA12 NA18 NA17 NA27 PA12

Claims (3)

[Claims] 1. A semiconductor device comprising, on one main surface of a substrate, a wiring group, a thin film transistor, an auxiliary capacitor, an uneven pattern, and a reflective electrode formed on the uneven pattern, wherein the uneven pattern is In a reflective liquid crystal display device configured using a concave portion formed in an insulating film formed simultaneously with an insulating film forming a thin film transistor, the uneven pattern crosses the wiring group, the thin film transistor, or the auxiliary capacitance portion. A reflection type liquid crystal display device, wherein the reflection type liquid crystal display device is arranged so as not to be disturbed. 2. A semiconductor comprising a wiring group, a thin film transistor, an auxiliary capacitance portion, and a reflective electrode formed on an uneven pattern on one main surface of a substrate, wherein the uneven pattern constitutes the thin film transistor. Alternatively, a reflective liquid crystal display device is formed using a plurality of island-shaped patterns formed of a semiconductor or a conductor formed simultaneously with a conductor. 3. The unevenness formed by using a concave portion formed by opening an insulating film formed at the same time as the insulating film forming the thin film transistor, and the semiconductor or conductor forming the thin film transistor. 3. The reflection-type liquid crystal display device according to claim 2, wherein the reflection type liquid crystal display device is configured by combining a plurality of island-shaped patterns formed of a semiconductor or a conductor formed at the same time.