JP3992393B2 - Method for manufacturing reflective liquid crystal display device and mask for manufacturing reflective liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing mask of the reflection type liquid crystal display equipment preparation and reflection type liquid crystal display device which performs display by reflecting light incident from the outside.
[0002]
[Prior art]
Liquid crystal display devices have been actively researched and developed as one of flat panel displays to replace CRTs. In particular, they take advantage of their low power consumption and thinness to make small battery-driven TVs and notebooks. It has been put into practical use as a computer, a car navigation system, a portable terminal device, and the like.
As a driving method of a liquid crystal display device, an active matrix TFT array using a thin film transistor (hereinafter referred to as TFT) as a switching element is mainly used because of high quality display. There are two types of display configurations: transmissive type and reflective type. The reflective type does not require a backlight source like the transmissive type, so it can achieve low power consumption and is extremely suitable for applications such as portable terminals. It can be said that. This reflective liquid crystal display device includes a first insulating substrate having scanning lines and signal lines, TFTs, reflective pixel electrodes, and the like provided in a grid pattern, and a first filter having a color filter, a black matrix, a counter electrode, and the like. Two insulating substrates are opposed to each other, and a liquid crystal is arranged between these substrates.
[0003]
In order to improve the display characteristics of the reflective liquid crystal display device, it is effective to increase the effective display area of the pixel portion of the liquid crystal display panel and increase the light utilization efficiency, that is, to increase the pixel aperture ratio. As a method of obtaining a TFT array of a high aperture ratio pixel, an interlayer insulating film made of an insulating resin having a sufficient thickness to eliminate a step caused by a scanning line, a signal line, and a TFT is formed, and the interlayer insulating film is formed on the interlayer insulating film. In addition, it is effective to form a pixel electrode with a large area so as to overlap with the above-described scanning lines and signal lines, and to connect the pixel electrode and the drain electrode of the TFT through a contact hole provided in the interlayer insulating film. According to this method, it is possible to prevent defects during rubbing caused by unevenness of the substrate.
On the other hand, as a method for improving the light utilization efficiency, the first insulating substrate described above can obtain scattered light having good directivity without applying a scattering film (forward scattering plate method) on the incident light side. A method of providing a film / pixel electrode has been proposed. This is to obtain good scattered light by providing appropriate irregularities on the surface of the reflective film / pixel electrode. Japanese Patent Application Laid-Open No. 9-90426 discloses a reflection type liquid crystal display device using this structure and having irregularities formed on the surface of a photosensitive insulating resin by photolithography.
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned Japanese Patent Application Laid-Open No. 9-90426, a mask on which both an uneven pattern and a contact hole pattern are formed is used, and the unevenness pattern and the contact hole pattern are changed by changing the dissolution rate at the time of development depending on the dimensional difference between them. However, it is very difficult to stably obtain irregularities for a reflective film that can form contact holes and obtain good scattered light on the resin surface. Furthermore, in order to obtain good scattered light with no specular reflection, the uneven pattern needs to have a certain size, and its dissolution rate is almost the same as the contact hole pattern dissolution rate. It is very difficult to distinguish and form.
[0005]
In JP-A-7-198919, an exposure mask with a controlled light transmission amount is used for exposure by changing the amount of light in multiple steps in the depth direction of the photosensitive film, and the surface of the reflector having irregularities. A forming method is disclosed. However, in order to obtain good scattering characteristics, it is necessary to eliminate a flat portion. For example, in the case of a 12.1 SVGA array, unevenness of about 200 to 300 is required in one pixel. It is necessary to make the uneven inter-pixel shape uniform in order to eliminate reflection spots with respect to the total number of pixels of 1.44 million pixels, and a mask capable of performing exposure satisfying the above conditions is very expensive, and It is very difficult to manufacture a simple mask. Further, the exposed and developed resin is heat-treated, but the resin is fluidized by this heat treatment and becomes a specific shape determined by the physical property value of the resin. Therefore, even if unevenness is formed by changing the exposure amount in multiple stages, the resin is adjacent. There is a problem that minute irregularities are deceived.
[0006]
The present invention has been made to solve the above-mentioned problems, and it is possible to stably obtain a high aperture ratio TFT array substrate that can be driven with low power and has excellent display quality by a simple process. An object of the present invention is to provide a method for manufacturing a reflective liquid crystal display device and a mask for manufacturing a reflective liquid crystal display device .
[0007]
[Means for Solving the Problems]
The manufacturing method of the reflective liquid crystal display device according to the present invention includes a plurality of scanning lines on an insulating substrate, a plurality of signal lines intersecting with the scanning lines, and individual sections defined by the scanning lines and the signal lines. a first step of forming a switching element in a pixel region, on the substrate, scanning lines insulating resin having photosensitivity, flatly applied to eliminate the level difference caused by the signal line and a switching element or the like, dew A second step of forming an interlayer insulating film having a scattering hole as a non-separation pattern in the pixel region and having a contact hole as a separation pattern on the drain electrode of the switching element by light and development; after forming the light-reflective metal film on the interlayer insulating film, and patterning, having a scattering irregularities caused by the interlayer insulating film in alignment with the position in each pixel region, via the contact hole switch A method of manufacturing a reflection type liquid crystal display including a third step of forming a ring element electrically connected to the reflective pixel electrode, in a second step, the exposure of the insulating resin, transmits ultraviolet rays A mask in a position aligned with a contact hole, having a UV filter layer that cuts UV light at a predetermined value within 20 to 80% and a light blocking material including a light blocking film that completely blocks UV light on the substrate A mask in which a light shielding material is not disposed in the pattern opening, a UV filter layer is disposed in the mask pattern opening at a position aligned with the pixel region, and a light shielding film is disposed in a position aligned with the convex portion of the scattering unevenness. Is used .
[0008]
Also, manufacturing mask of the reflection type liquid crystal display device according to the present invention, a first insulating substrate having scan lines provided in a grid pattern and the signal lines, switching elements, the interlayer insulation film and the reflection pixel electrodes When, it is opposed to the second insulating substrate having a color filter and a counter electrode, a non-separation pattern in manufacturing Oite, in a pixel region of these formed by arranging the liquid crystal between the substrates a reflection type liquid crystal display device A manufacturing mask used for exposure of an insulating resin for forming an interlayer insulating film having unevenness for scattering and a contact hole as a separation pattern on the drain electrode of the switching element, which transmits ultraviolet rays has a UV filter layer for cutting at a predetermined value of ultraviolet within 20-80% to the substrate, two or more layers of light-blocking member including a light shielding film to completely shield the ultraviolet, contact holes No masking material is placed in the mask pattern opening at the position aligned with the UV filter layer in the mask pattern opening at the position aligned with the pixel area, and further at the position aligned with the convex part of the scattering unevenness. A light shielding film is arranged.
Further, an a-Si film is used as the ultraviolet filter layer, and a Cr / CrO _X film is used as the light shielding film .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Reference Example 1
Reference examples of the present invention will be described below with reference to the drawings. FIG. 1 is a partial plan view showing a TFT array substrate constituting the reflective liquid crystal display device in this reference example , and FIG. 2 is a partial cross-sectional view showing a part of the manufacturing process of the TFT array substrate in this reference example . In the figure, 1 is an insulating substrate such as a glass substrate, 2 is a gate electrode wiring which is a scanning line formed in the row direction on the insulating substrate 1, 2a is a gate electrode, 3 is a common electrode wiring, 4 is a gate An insulating film 5 is an amorphous silicon film (hereinafter referred to as an a-Si film) which is a semiconductor layer of a TFT which is a switching element formed in each pixel region defined by the gate electrode wiring 2 and a source electrode wiring described later. , 6 is a low-resistance amorphous silicon film doped with an impurity serving as an ohmic contact layer of the TFT (hereinafter referred to as an n ⁺ -a-Si film), and 7 is a signal line formed on the insulating substrate 1 in the column direction. 7a is a source electrode, 8 is a drain electrode, 9 is a TFT channel section, 10 is a passivation film for protecting the TFT, and 11 is a gate electrode wiring 2 Together to eliminate the level difference resulting from the source electrode wiring 7 and TFT, the interlayer insulating film intentionally scattering irregularities are formed on the surface, 12 denotes a contact hole formed in the interlayer insulating film 11, 13 is an interlayer insulating film 11 This is a reflective pixel electrode formed above and connected to the drain electrode 8 of the TFT via the contact hole 12.
[0010]
Next, a manufacturing method of the TFT array substrate in this reference example will be described with reference to FIG. First, Cr is deposited on the insulating substrate 1 by sputtering or the like, and a plurality of gate electrode wirings 2 and common electrode wirings 3 are formed by photolithography. Next, a gate insulating film 4, an a-Si film 5, and an n ⁺ -a-Si film 6 made of silicon nitride are sequentially formed by using a plasma CVD method or the like, and the a-Si film 5 is formed by using a photolithography method. The n ⁺ -a-Si film 6 is patterned to form a TFT semiconductor layer. Further, a plurality of source electrode wirings 7, drain electrodes 8, and TFT channel portions 9 intersecting with the gate electrode wiring 2 are formed by sputtering or photolithography, and are partitioned by the gate electrode wiring 2 and the source electrode wiring 7. TFTs are formed in the individual pixel regions ( first step ). One end of the drain electrode 8 is opposed to the common electrode wiring 3 formed of a low resistance metal in the lower layer in the area of the reflective pixel electrode 13 to be formed later with the gate insulating film 4 as an inorganic insulating film interposed therebetween. This is a structure for forming a capacitor (capacitor). Further, a passivation film 10 for protecting the TFT is formed by a CVD method or the like (FIG. 2A).
[0011]
Next, a photosensitive insulating resin is applied flatly on the substrate so as to eliminate steps caused by the gate electrode wiring 2, the source electrode wiring 7, the TFT, etc., and exposure and development are performed by changing the exposure amount. As a result, an interlayer insulating film 11 having moderate scattering irregularities that are non-separation patterns in the pixel region and having contact holes 12 that are separation patterns on the drain electrode 8 of the TFT is formed ( second step). ). Here, a positive acrylic resin (JSR PC-335, i-line, h-line photosensitive product) having a low dielectric constant (<4) was applied as an insulating resin having photosensitivity to about 4 μm. The scattering irregularities were formed on the gate electrode wiring 2, the source electrode wiring 7, and the pixel region excluding a part of the capacitance forming position. In this reference example , the insulating resin is exposed by divided exposure in which the non-separation pattern and the separation pattern are arranged in different masks, and the non-separation pattern is a predetermined value within 20 to 80% of the exposure amount of the separation pattern. The exposure amount was as follows. As an exposure apparatus, an h-line stepper exposure machine was used to expose 12 parts of the contact hole with 400 mj / cm ² (UV light 1) and the unevenness in the pixel with 160 mj / cm ² (UV light 2) (FIG. 2). (B)).
[0012]
The dissolution rate of the positive photosensitive resin depends greatly on the decomposition rate of the photosensitive agent (this is referred to as “S-curve characteristic”), and the decomposition rate of the photosensitive agent at the uneven portion in the pixel region and the contact hole 12 portion. The difference was made in the dissolution rate, and development was performed in a time sufficient for the contact hole 12 to be resolved, thereby obtaining the depth A contact hole 12 and the depth B unevenness (FIG. 2C). . A weak alkaline developer (TMAH 0.4 wt%) was used as the developer. After the development, the film was baked at 200 to 230 ° C. for about 1 hour to form an appropriate scattering unevenness in the pixel region and an interlayer insulating film 11 having a contact hole 12 on the drain electrode 8 of the TFT. FIG. 3 shows the result of measuring the profile of the surface of the interlayer insulating film 11 obtained by the above steps with a stylus-type film thickness meter and confirming the surface shape. In the figure, (a) shows the contact hole part, (b) shows the shape of the concavo-convex part, and A in the figure shows the substrate surface which is the bottom of the interlayer insulating film 11. Thus, according to the manufacturing method in the present reference example, it was confirmed that the contact holes 12 separated to the bottom and the good scattering irregularities were formed.
[0013]
Next, the passivation film 10 in the contact hole 12 is etched to expose the drain electrode 8 in the contact hole 12. At the same time, the passivation film 10 in the terminal contact portion (not shown) including the transfer electrode is also removed. Furthermore, after forming a highly reflective film such as Al which is a light reflective metal film on the interlayer insulating film 11, patterning is performed, and unevenness for scattering by the interlayer insulating film 11 is provided at a position aligned with each pixel region, A reflective pixel electrode 13 electrically connected to the drain electrode 8 of the TFT through the contact hole 12 was formed ( third step, FIG. 2D). After forming an alignment film on the surface of the TFT array substrate obtained by the above process and another insulating substrate on which the counter electrode and the like are formed, the liquid crystal material is injected between the substrates by facing each other. The reflective liquid crystal display device in the reference example is completed.
[0014]
In this reference example , Al is used as the reflective pixel electrode 13, but a highly reflective film such as silver may be used. Further, an interlayer insulating film 11 by a child formed by colored resin such as black, it is possible to suppress reflection from the unnecessary portion. Further, the concave and convex pattern dimensions of the interlayer insulating film 11 may be randomly arranged. In the present reference example , the passivation film 10 is provided under the interlayer insulating film 11, but the passivation film 10 may not be provided. Also, in this reference example , the stepper method is used to perform divided exposure with different exposure pattern assignments, so that the processing capacity is not reduced compared to the conventional case. A batch exposure method is also applicable, but it is not suitable because the processing capability is greatly reduced.
[0015]
As described above, according to the TFT array substrate manufactured in this reference example , since the interlayer insulating film 11 is formed to be sufficiently thick, the reflective pixel electrode 13 is overlapped with the gate electrode wiring 2 and the source electrode wiring 7. It is possible to form a large area on the uppermost layer, drive a liquid crystal sufficiently with low power, and achieve a high-aperture reflective liquid crystal display device with a high contrast display quality and a simple process. Can be obtained stably. In addition, since the yield is improved by reducing display defects, the manufacturing cost can be reduced.
[0016]
Embodiment 1 FIG.
FIG. 4 is a partial cross-sectional view showing a part of the manufacturing method of the TFT array substrate according to the first embodiment of the present invention. In the figure, 14 is a mask for manufacturing a reflective liquid crystal display device used in the present embodiment, 15 is a glass material that is a base material that transmits ultraviolet light , 16 is a light shielding material A that is an ultraviolet filter layer, Reference numeral 17 denotes a light shielding material B which is a light shielding film that completely cuts off ultraviolet rays. In the figure, a represents a pixel pattern area, and b represents a contact hole pattern area. In the drawings, the same and corresponding parts are denoted by the same reference numerals and description thereof is omitted.
In the present embodiment, a first insulating substrate including a gate electrode wiring 2 and a source electrode wiring 7, a TFT, an interlayer insulating film 11, a reflective pixel electrode 13, and the like provided in a lattice shape, a color filter, and a counter electrode In the manufacture of a reflective liquid crystal display device in which a second insulative substrate having the above and the like is opposed to each other and a liquid crystal is disposed between these substrates , the pixel pattern area a in the pixel region is a non-separation pattern. It is a base material that transmits ultraviolet rays for exposure of an insulating resin for forming an interlayer insulating film 11 having irregularities and having a contact hole as a separation pattern in a contact hole pattern area b on the drain electrode 8 of the TFT. a light blocking member A16 is a UV filter layer for UV rays at a predetermined value within 20-80% in the glass material 15, the light shielding film to completely shield the ultraviolet Has two or more layers of light-blocking member including a certain light-blocking member B17, without placing a light shielding member on the mask pattern opening position aligned with the contact holes (shown in FIG. 4 b), aligned with a pixel area position In the mask pattern opening (shown by a in FIG. 4), a light shielding material A16 which is an ultraviolet filter layer is disposed, and a mask 14 in which a light shielding material B17 is disposed at a position aligned with the convex portions of the scattering unevenness is used. Is.
[0017]
A manufacturing method of the TFT array substrate in the present embodiment will be described. Note that the process up to the step of forming the passivation film 10 that protects the TFT on the insulating substrate 1 is the same as that in Reference Example 1, and thus the description thereof is omitted.
After the passivation film 10 is formed, a photosensitive low dielectric constant (<4) positive type acrylic resin (PC-335 made by JSR, i-line, h-line photosensitive product), gate electrode wiring 2 and source electrode wiring 7 Then, the surface is flatly applied so as to eliminate the level difference caused by the TFT, and is exposed and developed using a mask 14 by a photolithography method, on the gate electrode wiring 2, the source electrode wiring 7, and the capacitance forming position. Appropriate scattering irregularities are formed in the pixel region excluding a part, and a contact hole is formed on the drain electrode 8 ( second step ).
[0018]
In the reference example 1, the unevenness for scattering in the pixel region and the contact hole on the drain electrode 8 are arranged in different masks, and divided exposure is performed with different exposure amounts. with h-ray exposure apparatus, 400 mj / cm ² the contact hole ^portion, by exposing the scattering irregularities in the pixel region at 160 mJ / cm ^2, it was confirmed that good uneven and contact holes are formed Yes. On the other hand, in this embodiment, the uneven pattern for scattering and the contact hole pattern in the pixel region are arranged in the same mask 14.
FIG. 5 shows the transmittance (calculated value) of h-line with respect to the a-Si film thickness. If the light shielding film A16 having a thickness of 4 nm is left in the opening of the pixel pattern area a, 59.8% of the h line is absorbed. At this time, if exposure is performed at 400 mj / cm ² in order to sufficiently open the contact hole portion, the exposure amount of the concavo-convex pattern area portion in the pixel becomes 160 mj / cm ² , and an appropriate exposure amount can be obtained. Note that the mask 14 is “1” “0” control as to whether or not to leave the a-Si film in a part of the openings, and therefore can be manufactured at low cost and with high yield without requiring high accuracy. Moreover, the order of arrangement | positioning of the light shielding material A16 which has an ultraviolet filter function, and the light shielding material B17 which completely shields an ultraviolet-ray does not ask | require the structure of the mask 14. Further, as the light shielding material A having an ultraviolet filter function, another metal thin film of an a-Si film may be used. Further, as the light-shielding film B that completely shields ultraviolet rays, a film of Mo, MoSi, or the like can be used in addition to the Cr / CrO _X film.
[0019]
As described above, after exposure using the mask 14, development is performed using a weak alkaline developer (TMAH 0.4 wt%), baking is performed at 200 to 230 ° C. for about 1 hour, and moderate scattering irregularities are formed in the pixel region. Then, an interlayer insulating film 11 having a contact hole was formed on the drain electrode 8. Since the subsequent steps are the same as those in Reference Example 1, description thereof is omitted.
Also in this embodiment, the same effect as the above-described Reference Example 1 can be obtained, and furthermore, in this embodiment, the processing capability is not reduced even when applied to the batch exposure method, so that the restrictions on the process apparatus are relaxed. .
[0020]
【The invention's effect】
As described above, according to the present invention, the scanning line insulating resin having photosensitivity, flatly applied to eliminate the level difference caused by the signal line and the switching element or the like, exposure light and developed, and has a scattering irregularities are inseparable pattern in the pixel region, in the step of forming an interlayer insulating film having a contact hole is the separation pattern on the drain electrode of the switching element, the exposure of the insulating resin, transmits ultraviolet The substrate to be used has an ultraviolet filter layer that cuts ultraviolet rays by a predetermined value within 20 to 80% and a light shielding material that includes two or more layers of light shielding films that completely shield ultraviolet rays. No light shielding material is placed in the mask pattern opening, an ultraviolet filter layer is placed in the mask pattern opening at the position aligned with the pixel area, and the scattering unevenness Since to use a mask arranged a light-shielding film to a consistent position in part, to obtain a reflection type liquid crystal display having a high aperture ratio which is excellent in display quality can be low power driving stably by a simple process It has become possible.
[Brief description of the drawings]
FIG. 1 is a partial plan view showing a TFT array substrate constituting a reflective liquid crystal display device which is a reference example 1 of the present invention.
FIG. 2 is a partial cross-sectional view showing a part of a manufacturing method of a TFT array substrate in Reference Example 1 of the present invention.
FIG. 3 is a diagram showing the results of measuring the surface shape of an interlayer insulating film prepared in Reference Example 1 of the present invention with a stylus type film thickness meter.
FIG. 4 is a partial cross-sectional view showing a part of the manufacturing method of the TFT array substrate in the first embodiment of the present invention.
FIG. 5 is a graph showing h-line transmittance (calculated value) with respect to the a-Si film thickness;
[Explanation of symbols]
1 insulating substrate, 2 gate electrode wiring, 2a gate electrode,
3 common electrode wiring, 4 gate insulating film, 5 a-Si film,
6 n ⁺ -a-Si film, 7 source electrode wiring, 7a source electrode,
8 drain electrode, 9 channel part, 10 passivation film,
11 interlayer insulation film, 12 contact hole, 13 reflective pixel electrode,
14 mask, 15 glass material, 16 light shielding material A, 17 light shielding material B.

Claims (3)

A first step of forming a plurality of scanning lines on the insulating substrate, a plurality of signal lines intersecting with the scanning lines, and switching elements in individual pixel regions defined by the scanning lines and the signal lines. ,
On the substrate, the scanning line insulating resin having photosensitivity, flat coated so as to eliminate the level difference caused by the signal line and the switching element or the like, exposure light and developed, a pixel region inseparable and has a scattering irregularities is a pattern, a second step of forming an interlayer insulating film having a contact hole is the separation pattern on the drain electrode of the switching element,
A light-reflective metal film is formed on the interlayer insulating film, patterned, and has scattering irregularities due to the interlayer insulating film at positions aligned with individual pixel regions. A method of manufacturing a reflective liquid crystal display device, comprising a third step of forming electrically connected reflective pixel electrodes ,
In the second step, for the exposure of the insulating resin, an ultraviolet filter layer that cuts ultraviolet rays at a predetermined value within 20 to 80% on a substrate that transmits ultraviolet rays, and a light shielding film that completely blocks ultraviolet rays. The mask pattern opening at a position aligned with the contact hole is not disposed, and the ultraviolet filter is disposed at the mask pattern opening at a position aligned with the pixel region. A method of manufacturing a reflective liquid crystal display device, comprising: using a mask in which a layer is disposed and the light shielding film is disposed at a position aligned with the convex portions of the scattering irregularities . Opposing the scanning line and the signal line provided in a grid pattern, a switching element, a first insulating substrate having an interlayer insulating film and the reflection pixel electrodes, a second insulating substrate having a color filter and a counter electrode is, the separation pattern on the drain electrode of the switching element and having fraud and mitigating risk scattering recesses and projections having a non-separation pattern in the pixel region in the manufacturing of these formed by arranging the liquid crystal between the substrates a reflection type liquid crystal display device A manufacturing mask used for exposure of an insulating resin for forming the interlayer insulating film having a contact hole,
Has a UV filter layer for UV rays to a substrate which transmits ultraviolet rays at a predetermined value within 20-80%, two or more layers of light-blocking member including a light shielding film to completely shield the ultraviolet, to the contact hole The light shielding material is not disposed in the mask pattern opening at the aligned position, the ultraviolet filter layer is disposed in the mask pattern opening at the position aligned with the pixel region, and further aligned with the convex portion of the scattering unevenness. A mask for manufacturing a reflective liquid crystal display device, characterized in that the light shielding film is disposed at the position . The mask for manufacturing a reflective liquid crystal display device according to claim 2 , wherein an a-Si film is used as the ultraviolet filter layer and a Cr / CrO _X film is used as the light shielding film .

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