JPH03148636A - Manufacture of active matrix type liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain a large aperture rate and increase the transmissivity by providing a transparent conductive film on a substrate, performing back exposure using scanning electrode wires and a semiconductor film as a mask, and then patterning the film and thus forming picture element electrodes. CONSTITUTION:The glass substrate 30 is provided with scanning electrode lines 36 and gate electrodes 31 which are connected thereto, and they are covered with a gate insulating film 32. Then a protection insulating film 33 is arranged on an Si film 34 and a drain electrode 38 and a source electrode 39 are formed across an Si film 35 with low resistance to form a TFT 40. When a picture element electrode 37 is formed, the scanning electrode lines 36 and Si films are utilized for the back exposure to form picture element electrodes inside measures. Thus, TFTs are formed in matrix nearby the intersections of the scanning lines 36 and signal electrode lines 34. The pattern of an insulating film 41 is formed and covered with an orienting film 42. A light shield film 45, an ITO electrode 46, and an orienting film 47 are provided on an opposite substrate 44 at positions facing the TFTs, the substrates are adhered together across spacers, and liquid crystal is injected to complete the element. In this configuration, the electrodes 37 can be put extremely close to the signal electrode lines and the aperture rate is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) This invention relates to a method for manufacturing an active matrix liquid crystal display element.

(Prior art) As electronic devices become smaller, lighter, and consume less power, CRT (Cathode
Research and development of flat panel displays is being actively conducted as an alternative to ode ray tubes. Among these, liquid crystal displays are attracting the most attention because of their ability to display large areas, full color display, and low current/low voltage operation.

There are various operating systems for liquid crystal displays depending on their purpose, but the active matrix system is characterized by its ability to display full-color moving images at high resolution. The active matrix method is a method in which each pixel is an intersection of electrodes arranged in a matrix, and a switching element is provided for each pixel. The active matrix method uses nonlinear diode type and thin film transistor (T
(PT) type, of which the latter is particularly actively researched and developed. One substrate has an array of TPT and capacitors arranged on a glass plate.
For example, IEEE Trans on Electron Devices (IEEE Trans, on
It is described in detail in Electron Devices, Vol. 20, pages 995 to 20 (1973).

FIG. 6 is a schematic plan view of a TFT array substrate using TPT, and TPT is shown as an equivalent circuit. In FIG. 6, the glass substrate has signal electrode lines 2 arranged substantially parallel to each other at equal intervals, and signal electrode lines 2 that are substantially orthogonal to the signal electrode lines 2 and are formed using an interlayer insulating film such as silicon oxide. FIG. 7 shows a device consisting of a scanning electrode line 3 electrically insulated from the signal electrode line 2 and a display pixel section 4 arranged in the vicinity of the intersection of the signal electrode line 2 and the scanning electrode line 3 and having a matrix shape as a whole. 3 is a cross-sectional view showing an example of a display pixel section 4. FIG.

In FIG. 7, on a glass substrate 10, there is formed a gate 4 electrode 1l, a gate insulating film 12, a semiconductor film 13, a semiconductor protective film 14, a low-resistance semi-integral film 5-, a source electrode 16, and a drain electrode 17. TPT is connected to the pixel electrode 18 at the source electrode 16 portion. Here, gate electrode 1
1 is integrated with the scanning electrode line 3 in FIG. 6, and the drain electrode 17 is integrated with the signal electrode line 2 in FIG. In order to protect the TPT, its upper part is covered with an insulating film 19 made of silicon oxide or the like, and an alignment film 20 is further formed on this. On the other hand, on the glass substrate 10, T
A light shielding film 22 is formed to face the PT, and furthermore, a counter electrode 23 and an alignment film 24 are formed in this order. A liquid crystal 25 is placed between the two glass substrates 10 and 21.
is being held.

The steps for manufacturing the TFT array substrate shown in FIG. 7 are as follows. First, the scanning electrode line 3 and the gate electrode l1 shown in FIG. 6 are simultaneously formed on the glass substrate 10, and the gate insulating film 12, the semiconductor film 13, and the semiconductor protective film 14 are sequentially formed thereon.

Next, after forming the semiconductor protective film 14, a low resistance semi-integral film 15 is formed, and the semiconductor film 13 and the low resistance semiconductor film 15 are simultaneously formed into the same shape. Thereafter, the pixel electrode 18 is formed and the gate insulating film 12 on the electrode pad is removed, and the signal electrode line 2, source electrode 16, and drain electrode 17 shown in FIG. 6 are formed. Subsequently, in this state, since the source electrode 16 and the drain electrode 17 are short-circuited by the low-resistance semiconductor film 15, the source electrode 16 and the drain electrode 17 are short-circuited by the low-resistance semiconductor film 15. Using as a mask, the low resistance semiconductor film 15 on the semiconductor protective film l4 is removed. Then, by sequentially forming an insulating film 19 and an alignment film 2G on the glass substrate 10, T
The FT array board is completed.

(Problem to be Solved by the Invention) However, in this type of liquid crystal display element, the pixel electrode 18, the drain electrode 17, and the signal electrode line 2 are formed close to each other in the same plane. In some cases, the drain electrode 17 and the signal electrode line 2 were short-circuited, resulting in defective pixels. Therefore, it became necessary to increase the distance between the pixel electrode 18, the drain electrode 17, and the signal electrode line 2, and the aperture ratio sometimes decreased.

This invention was made in view of such conventional circumstances.

[Structure of the Invention] (Means for Solving the Problems) This invention provides a gate electrode, a gate insulating film, a gate insulating film, and a gate electrode on a first substrate.
an array substrate in which thin film transistors each consisting of a semiconductor film, a source electrode, and a drain electrode are arranged in a matrix near the intersections of a plurality of scanning electrode lines and signal electrode lines, and each thin film transistor is connected to a pixel electrode; This invention relates to a method for manufacturing an active matrix liquid crystal display element in which a liquid crystal is sandwiched between a second substrate and a counter substrate formed with a counter electrode formed thereon. This invention forms pixel electrodes by forming a transparent conductive film on a first substrate and then patterning the transparent conductive film using a back exposure method using a scanning electrode line and a semiconductor film as a mask. It has a process to In addition, in place of the above steps, the present invention includes a step of first forming a shielding film on the first substrate and then patterning to form a black matrix, and a step of forming a black matrix after forming a transparent conductive film on the first substrate. , a process of forming pixel electrodes by patterning a transparent conductive film using a back exposure method using scanning electrode lines and a black matrix as a mask.

(Function) In this invention, by forming the pixel electrode from the transparent conductive film by back exposure, the transparent conductive film on the foreign matter through which light does not pass, such as metal powder, is removed. Short circuits between the drain electrode and the signal electrode line are reduced, and point defects can be reduced.

Furthermore, since the signal electrode line and the pixel electrode are formed close to each other, the aperture ratio is increased and a display element with high transmittance can be formed.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of an active matrix liquid crystal display element obtained according to an embodiment of the first invention, and the manufacturing process will be explained accordingly. In FIG. 1, first, for example, a molybdenum-tantalum (Mo-Ta) alloy film is formed to a thickness of about 0.2 μm by sputtering or the like on the whole surface of a first substrate 30 made of glass, and then photolithography is performed. A striped scanning electrode line (not shown) and a gate electrode 31 electrically connected to the scanning electrode line are formed by one method. Next, plasma CvD (Ch
chemical vapor deposition)
For example, silicon nitride (S) with a thickness of about 0.3 μm is
i Nx ) films, for example, an amorphous silicon (a-Si) film with a thickness of about (L1 μm) and a SiNx film with a thickness of about 0.3 μm,
The gate insulating film 32 made of the SiNx film at the bottom is obtained by sequentially depositing the SiNx film at the bottom, and the SiNx flk at the top is processed by a photolithography method to form a semiconductor protective film 33 on the inner side of the part corresponding to the gate electrode 31. Form into an island shape. Next, the plasma CVD method is used to reduce the thickness to about 0.
, 05 μm, and a semiconductor film 34 and a low-resistance semiconductor film 35 are simultaneously formed by photolithography.

FIG. 2 is a schematic plan view showing the pattern of the scanning electrode line 36 and the semiconductor film 34 in this embodiment.

As can be seen from the figure, the laminated film of the semiconductor film 34 and the low-resistance semiconductor film 35 has a shape similar to the signal electrode line 2 in FIG. is forming.

Next, for example, ITO (Ind.
A transparent conductive film made of (Ium Tin Oxide) is deposited to a thickness of about 0.1 am by sputtering, and a pixel electrode 37 is formed by photolithography. Here, when forming the pixel electrode 37, for example, a negative type photoresist is applied, and exposure and development are performed from the other main surface side of the first substrate 30. By doing this, a resist pattern is formed inside the square formed by the scanning electrode 1136 and the semiconductor film 34, and when the transparent conductive film is etched, the pixel electrode 37 is formed inside the square.

Next, make molybdenum (Mo) with a thickness of about 0.05 μm, for example.
An aluminum (Al) film with a thickness of about 1.0 μm is deposited by sputtering or the like, and a striped signal electrode line (not shown) is electrically connected to the signal electrode line by photolithography. Drain electrode 38 and source electrode 3
9 is formed at the same time. At this time, the signal electrode line and the drain electrode 38 are formed on the inner side of the pattern of the laminated film of the semiconductor film 34 and the low-resistance semiconductor film 35, while the source electrode
9 is formed to be electrically connected to the pixel electrode 37. Furthermore, in this state, a short circuit occurs between the drain electrode 38 and the source electrode 39 due to the low resistance semiconductor film 35, so this portion of the low resistance semiconductor film 35 is removed by etching. In this way, the gate electrode 3 is placed on the T51 substrate 30.
1. Gate insulating film 32, semiconductor film 34, drain electrode 38
Although not shown, the TFTs 40 are respectively located near the intersections of the plurality of scanning electrode lines 36 and the signal electrode lines, and are arranged in a matrix as a whole. Subsequently, a film made of silicon nitride, for example, is deposited on the whole surface of the first substrate 30 in a thickness of about 0.1 μm.
The insulating film 41 is deposited to a thickness of approximately 1-0 μm from m to a desired pattern using photolithography. Thereafter, an alignment film 42 made of polyimide, for example, is coated on the entire surface of the first substrate 30 by, for example, a spinner coating method, baked at an appropriate temperature between about 100° C. and about 200° C., and then rubbed. I do. In this way, a desired array substrate 43 is obtained.

On the other hand, on the entire surface of the second substrate 44, a light shielding film 45 made of, for example, AI is formed at a position facing the TFT 40 of the array substrate 43, and a counter electrode 46 made of, for example, ITO is further formed. After this, as before, an alignment layer made of polyimide, for example, is placed on the entire surface of the second substrate 44.
4147 is applied by, for example, a spinner coating method, baked at an appropriate temperature between about 100° C. and about 200° C., and then rubbed. In this way, the desired counter substrate 48 is obtained. Next, the array substrate 43 and the counter substrate 48 are placed together with a spacer (not shown), for example, alumina beads of about IO μm, so that the alignment films 42 and 47 face each other. Except for the portion that will become the entrance, they are bonded together in approximately parallel to each other with a sealing material (not shown) made of, for example, an epoxy adhesive at a thickness of approximately 10 μm. Next, after the liquid crystal 49 is injected through the injection port described above, the injection port is sealed with a sealant (not shown) made of, for example, an epoxy adhesive.

In this way, a desired active matrix type liquid crystal display element in which the liquid crystal 49 is sandwiched between the array substrate 43 and the counter substrate 48 is obtained.

In this embodiment, after forming a transparent conductive film on the entire surface of the first substrate 30, the transparent conductive film described above is patterned using a back exposure method using the scanning electrode line 36 and the semiconductor film 34 as a mask. As a result, a pixel electrode 37 is formed.

As a result, if foreign matter such as metal powder is attached to the first substrate 30 before forming the pixel electrode 37, the transparent conductive film is removed on the foreign matter, so that the pixel electrode 37
Short circuits between the drain electrode 38 and the signal electrode line are reduced. In addition, the pixel electrode 37 is placed very close to the signal electrode line.
The aperture ratio of the display element is improved compared to the conventional one.

FIG. 3 shows a cross-sectional view of an active matrix liquid crystal display element obtained according to an embodiment of the second invention, and this will be explained according to the manufacturing process. In FIG. 3, first, a light shielding film made of, for example, chromium (C'') is formed to a thickness of about 0.15 μm by sputtering or the like on the entire surface of a first substrate 30 made of, for example, glass, and then photolithography is performed. A grid-like black matrix 50 is formed by one method.

Next, an insulating layer 51 made of SiOx with a thickness of about 12 μm is formed on the entire surface by, for example, a plasma CVD method or the like. Next, an insulating layer 51 made of SiOx is formed to a thickness of about 12 μm by a sputtering method or the like. A film is formed to a thickness of 0.2 μm, and a striped scanning electrode line (not shown) and a gate electrode 31 electrically connected to the scanning electrode line are formed by photolithography.

FIG. 4 is a schematic plan view showing the pattern of the scanning electrode lines 36 and the black matrix 50 in this embodiment. As can be seen from the figure, the black matrix 50 has a shape similar to the signal electrode line 2 in FIG. 7, and forms a predetermined square with the scanning electrode line 36.

Next, by plasma CVD method or the like, a thickness of about 0.3 mm is formed, for example.
μm SiOx film, e.g. a-Si with a thickness of about 0.1 μm
A SiNx film with a thickness of about L3 pm is sequentially deposited to obtain a gate insulating film 32 consisting of the SiOx film at the bottom, and a SiNx film at the top by photolithography.
The iNx film is processed to form a semiconductor protective film 33 into an island shape inside a portion corresponding to the gate electrode 31. Subsequently, an n-type a-Si film having a thickness of about 0.05 μm is formed by plasma CVD, and a semiconductor film 34 and a low-resistance semiconductor film 35 are simultaneously formed by photolithography. Next, for example, I To (In
A transparent conductive film made of (dfus tin oxide) is deposited to a thickness of about 0.111 m by sputtering, and a pixel electrode 37 is formed by photolithography.

Here, when molding the three pixel electrodes, for example, a negative type photoresist is applied, and exposure and development are performed from the other main surface side of the first substrate 30. By doing this, the scanning electrode line 3
A resist pattern is formed only on the inside of the square formed by 6 and the black matrix 50, and when the transparent conductive film is etched, the pixel electrode 37 is formed inside the square.

Thereafter, by performing the same steps as in the embodiment shown in FIG. 1, a desired active matrix liquid crystal display element can be obtained.

In this embodiment, a light shielding film is formed on the first substrate 30 and then patterned to form the black matrix 50, and a transparent conductive film is formed on the first substrate 3G, and then the scanning electrode lines 36 and The pixel electrode 37 is formed by patterning the transparent conductive film using a back exposure method using the black matrix 50 as a mask. As a result, this embodiment has the same effects as the embodiment shown in FIG. In particular, in this embodiment, since the black matrix 50 is composed of a light shielding film, the semiconductor 1113
The above-mentioned effect is more remarkable than the embodiment shown in FIG.

FIG. 5 shows a cross-sectional view of an active matrix liquid crystal display element obtained according to another embodiment of the second invention, and this will be explained according to the manufacturing process. In FIG. 5, first, a light shielding film made of, for example, Cr is formed to a thickness of about 0.15 μm on the entire surface of a first substrate 30 made of, for example, glass, by sputtering, and then a grid is formed by photolithography. A black matrix 50 having a shape is formed. Subsequently, an insulating layer 51 made of SiOx and having a thickness of approximately 0.2 μm is formed over the entire surface by, for example, plasma CVD. Next, for example, a Mo-Ta alloy film is formed to a thickness of about 0.2 μm by sputtering or the like, and striped scanning electrode lines (not shown) are formed by photolithography.
Gate electrode 31 electrically connected to this scanning electrode line
to form. Here, the positional relationship between the scanning electrode lines and the pattern of the black matrix 50 is the same as in the case of FIG. 4.

Subsequently, a -th layer gate insulating film 32a made of SiOx and having a thickness of approximately 0.2 μm is formed on the entire surface of the first substrate 30 by, for example, plasma CVD. Next, a transparent conductive film made of, for example, ITO is deposited on the whole surface of the first substrate 30 to a thickness of about 0.1 μm by sputtering, and a pixel electrode 37 is formed by photolithography. Here, when forming the pixel electrode 37, for example, a negative type photoresist is applied, and exposure and development are performed from the other main surface side of the first substrate 30. By doing this, the scanning electrode! 136
A resist pattern is formed only inside the square formed by the black matrix 50, and when the transparent conductive film is etched, the pixel electrode 37 is formed inside the square. Next, SiOx with a thickness of about 0.2 μm is deposited on the entire surface of the first substrate 30 by, for example, plasma CVD.
A second layer gate insulating film 32b is formed.

Next, by plasma CVD method etc., a thickness of about 0.0, for example, is formed.
A 5 μm a-Si film and an approximately 0.2 μm thick SiNx film are successively deposited, and the uppermost SiNx film is processed by photolithography to form a semiconductor layer inside the portion corresponding to the gate electrode 31. The protective film 33 is formed into an island shape. Subsequently, the thickness was approximately 0.05 μm by plasma CVD method.
An n-type a-Si film is formed, and a semiconductor film 34 and a low-resistance semiconductor film 35 are simultaneously formed by photolithography. Next, the pixel electrode 3
A contact hole for electrically connecting 7 and source electrode 39 is formed by photolithography. Subsequently, molybdenum (Mo
) film and an aluminum (AI) film with a thickness of approximately 1.0 μm are deposited by sputtering or the like, and a striped signal electrode wire (not shown) is electrically connected to the signal electrode wire by photolithography. A drain electrode 38 and a source electrode 39 are formed at the same time. At this time, the signal electrode line and the drain electrode 38 are formed on the inner side of the pattern of the black matrix 50, while the source electrode 39 is formed so as to be electrically connected to the pixel electrode 37 through the above-mentioned contact hole. Ru. Furthermore, in this state, a short circuit occurs between the drain electrode 38 and the source electrode 39 due to the low resistance semiconductor film 35.
is removed by etching. In this way, the first substrate 30
A gate electrode 31, a gate insulating film 32, and a semiconductor film 34 are formed on the top.
, a TFT 40 composed of a drain electrode 38 and a source electrode 39 is obtained. Thereafter, by performing the same steps as in the embodiment shown in FIG. 1, a desired active matrix liquid crystal display element can be obtained.

In this embodiment, as in the embodiment shown in FIG.
After forming a light shielding film on the first substrate 30, patterning is performed to form a black matrix 50, and after forming a transparent conductive film on the first substrate 3G, the scanning electrode line 36 and the black matrix 50 are used as a mask. The pixel electrode 37 is formed by patterning the transparent conductive film using the back exposure method. As a result, this embodiment has the same effects as the embodiments described so far.

In particular, in this embodiment, by interposing the gate insulating film 32b between the pixel electrode 37 and the drain electrode 38, it is possible to completely eliminate short circuits between the pixel electrode 37 and the drain electrode 38 and the signal electrode line due to foreign matter. did it.

In the embodiment shown in FIG. 1, when it is necessary to improve the light-shielding property of the laminated film of the semiconductor film 34 and the low-resistance semiconductor film 35 when using the back exposure method, a predetermined layer is formed on the low-resistance semiconductor film 35. For example, MO with a thickness of about 0.1 μm.
After laminating the films, the pixel electrode 37 may be formed.

[Effects of the Invention] This invention allows the signal electrode line and the pixel electrode to be formed close to each other by forming the pixel electrode using a back exposure method using the scanning electrode line and the semiconductor film or black matrix as a mask. Therefore, it is possible to manufacture an active matrix liquid crystal display element with a large aperture ratio and high transmittance with a high yield.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an active matrix liquid crystal display element obtained by an embodiment of the first invention, and FIG. 2 is a schematic diagram showing the pattern of scanning electrode lines and semiconductor films in the embodiment shown in FIG. A plan view, FIG. 3 is a sectional view showing an active matrix liquid crystal display element obtained by an embodiment of the second invention, and FIG. 4 is a pattern of scanning electrode lines and a black matrix in the embodiment shown in FIG. 3. 5 is a cross-sectional view showing an active matrix liquid crystal display element obtained by another embodiment of the second invention, FIG. 6 is a schematic plan view of a conventional TFT array substrate,
FIG. 7 is a cross-sectional view showing an example of a display pixel portion of a conventional active matrix liquid crystal display element. 30.--First substrate, 31.--Gate electrode 3
2.32a, 32b--gate insulating film 34...semiconductor film 36--scanning electrode line, 3-pixel electrode 38-
・・Drain electrode, 39−・−Source electrode 40・
-・TFT, 43-・array board 46・
・-Counter electrode, 48...Counter substrate 49...1 liquid crystal, 5G-...Black matrix agent Patent attorney Nori Chika Ken Yudo Takehana Kikuoaki vs. Isaka 452 first film 44 straw 2XKt) 46j Toru l
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Claims (2)

[Claims] (1) Thin film transistors consisting of a gate electrode, a gate insulating film, a semiconductor film, a source electrode, and a drain electrode are arranged on the first substrate near the intersections of a plurality of scanning electrode lines and signal electrode lines in a matrix shape, and In a method for manufacturing an active matrix liquid crystal display element, in which a liquid crystal is sandwiched between an array substrate in which a pixel electrode is connected to each thin film transistor, and a counter substrate in which a counter electrode is formed on a second substrate, After forming a transparent conductive film on the first substrate, the pixel electrode is formed by patterning the transparent conductive film using a back exposure method using the scanning electrode line and the semiconductor film as a mask. 1. A method for manufacturing an active matrix liquid crystal display element, comprising the steps of: (2) Thin film transistors consisting of a gate electrode, a gate insulating film, a semiconductor film, a source electrode, and a drain electrode are arranged on the first substrate near the intersections of a plurality of scanning electrode lines and signal electrode lines in a matrix form, and In a method for manufacturing an active matrix liquid crystal display element, in which a liquid crystal is sandwiched between an array substrate in which a pixel electrode is connected to each thin film transistor, and a counter substrate in which a counter electrode is formed on a second substrate, A step of forming a light shielding film on the first substrate and then patterning to form a black matrix; and after forming a transparent conductive film on the first substrate, masking the scanning electrode line and the black matrix. A method for manufacturing an active matrix liquid crystal display element, comprising the step of forming the pixel electrode by patterning the transparent conductive film using a back exposure method.