JPH01224726A - Production of active matrix element for liquid crystal display - Google Patents

Abstract

PURPOSE:To reduce the number of formed film layers and the number of patterning masks and to produce an element with a low cost by patterning a lower Cr electrode by wet etching and laminating an a-Si film and an upper Cr film and patterning the upper Cr film by wet etching and patterning the a-Si film and insulating the side face of the a-Si film of a diode. CONSTITUTION:After a Cr film 30 formed on a transparent insulating substrate 10 directly or through a transparent conductive film is patterned by the wet etching method, an a-Si film 40 and a Cr film 50 are laminated on the Cr film 30. A resist film is used as the mask to pattern the upper Cr film 50 by the wet etching method, thereby forming upper electrodes of diodes 11 and 12. Thereafter, the resist film and the upper Cr film 50 are used as the mask to form an a-Si film pattern of each diode by etching, and the resist film is incinerated by plasma etching in atmospheric oxygen, and the side face of the a-Si film is oxidized to form an insulating film. Thus, a low-cost active matrix element for liquid crystal display is obtained which has a small number of formed film layers and a small number of masks and does not use a CCl4 dry etching device.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is characterized in that an amorphous silicon (hereinafter referred to as a-3t) diode connected in antiparallel between a scanning line and a data line is connected in series with tBi for driving a liquid crystal. The present invention relates to a method of manufacturing an active matrix element for a liquid crystal display for a connected liquid crystal television or the like.

[Conventional technology]

In order to improve the image quality of liquid crystal televisions, active matrix driven liquid crystal televisions using a-3T transistors or diodes have been developed, and products are now on the market. Among these types of devices, those that use diodes have a small number of steps, are low in cost, and are stable because the diodes are connected in antiparallel to form a ring diode configuration. It has excellent characteristics.

Fig. 2 shows an equivalent circuit diagram of an active matrix type liquid crystal display device using diodes. The scanning lines 411 and data lines 2 formed on separate glass substrates form a matrix, and by performing matrix scanning driving, the intersection points are The liquid crystals 4 present in 111M are sequentially electrically converted to 111M. The active matrix element intersects the liquid crystal drive electrode and the scanning line! A ring diode 3 is formed by connecting several series-connected diodes in parallel between the two diodes.

Fig. 3 (Ml to (8) shows the manufacturing process of an active matrix element having two series A-51 diodes as in the conventional structure shown in Fig. 8; in Fig. 3, Na-free borosilicate glass or A transparent conductive film 20 of ITO (indium tin oxide) + 5nO1 etc. formed by vapor deposition or sputtering on a glass substrate 10 in which 5108 is coated on soda glass by dipping or sputtering. Cr1130 with a thickness of about 1000. Approx.
An A-5L film 40 with a thickness of about 1,000 people, a Cr film 0 with a thickness of about 1,000 people and an AJI film 180 with a thickness of about 3,000 people were formed using sputtering. The pin junction consists of 9 layers approximately 500 people thick and 1 layer approximately 3000 people thick.
11 (non-doped N) and 0 with a thickness of about 500
The 8-order layer consists of Cr using photolithography method.
11250. a-3t membrane 40. The Cr film 0 is patterned, and the two diodes 11 and 12 are patterned using the Cr film 1. a-5l film 41°Cr film formation 1 and Cr film formation 2. a
-31 film 4L Cr film formation 2 (Figure b). This photolithography method involves forming a resist film with a desired diode pattern, and using this as a mask, first (HzPO
* The M film 80 is patterned using a +HNOs+CHi (:0OH) solution. This resist film is A71
Cr film was formed by plasma etching using the mask reinforced in step 2. a-5l membrane 40. Cr film is formed and patterned. First, Cr11950 is converted into CC1a and 0
．． A mixed gas of
Plasma etching was performed under the conditions of 5 Torr and power of 200 to 1000 W, followed by cp and 0.5 Torr. A mixed gas of 0.05 Torr was introduced.

A-5iJIQ40 was plasma-etched under the conditions of lk-, and after i, it was etched again using a mixed gas of CC7 and O.
．． Etching of the Cr film 0 is performed under conditions of 1 to 0, 5 Torr, and 300 to 700 W.

Next, using a photolithography method, a transparent conductive film was formed using a mixed solution of ferric chloride and hydrochloric acid using a resist mask.
21.22.25
(Figure cL, after this, N11. and 5l) II
A SiN film for protecting the diode is formed by plasma CVD method in which a mixed gas of SF and Cs is decomposed by plasma.
(The SIN film pattern 61 was formed by photolithography using plasma etching using a mixed gas of JFs.
．． 62.63 (Figure d), and then use a sputtering method to form a 1000mm thick Cr film and a 500mm thick Cr film.
A metal film made of a 2N adhesive film having a thickness of 2N is laminated, and metal film patterns 71, 72, and 73 are formed by photolithography. As a result, diode 11 and diode 12
are connected in series and inserted between the pixel electrode 25 and the scanning &I 73 (Figure e).The reason why a laminated film of a Cr film and an A7 film is used as the metal film is that the atmosphere during etching of M is similar to that of the ITO film. This is to prevent damage.

[Invention tries to solve it! ! 1! [Problem] The conventional manufacturing process for active matrix elements for liquid crystal displays as explained in FIG. 3 has the following problems.

+11 film eyebrows IT 0FI20. Cr1li30
．． a-5te4o, Cr film formation 0. A7 membrane 80
．． SiN film (patterns 61, 62, and 63 are formed)
and 8W of Cr film and kI film for double layer film (forming pattern ?1,72.73)! becomes the majority of i.

(2) Cr film is formed to form diodes 11 and 12.
．． a-31 membrane 40. When patterning 3711 of Cr1i30 by plasma etching, it is necessary to use a reactive ion etching mode with strong anisotropy to avoid side etching, which requires high power and potential. It is also necessary to mount the substrate on the electrode opposite to the ground side, which causes many problems with the etching equipment.

(For CC7, used for etching 31Cr, a
There is a restriction that stainless steel cannot be used in the device because radicals are generated and corrode Cr, and since the oil in the vacuum pump deteriorates due to Cr, countermeasures are required.

The object of the present invention is to eliminate the above-mentioned problems, reduce the number of film layers,
It is an object of the present invention to provide a low-cost method for manufacturing an active matrix element for a liquid crystal display, which requires a small number of masks and does not use a CCl2-based dry etching device.

(Means for solving !ill!J) The above !l!J
In order to solve this problem, the present invention provides a method for forming a diode of an active matrix element in which an anti-parallel A-3L diode is connected between a scanning line and a data line in series with a liquid crystal driving electrode. After patterning the Cr film formed directly on the substrate or via a transparent conductive film by wet etching, an A-3L film and a Cr film are laminated thereon,
After patterning the upper Cr film by wet etching using the resist film as a mask to form the upper electrode of each diode, an a-5L film pattern of each diode is formed by etching using the resist film and the upper Cr1III as a mask. The resist film is ashed by plasma etching in an atmosphere, and the side surfaces of the a-3ill are oxidized to form an insulating film.

[Effect]

Since etching of Cr1lQ is done by wet etching,
Dry etching using C14 gas or fluorine gas,
Reactive ion etching is no longer required, and the lower Cr119
Since the patterning is also performed separately, this Cr film can also be used for connection wiring, ITO electrodes, or wiring. Further, since an insulating film is formed on the side surface of the a-31 film at the same time as the iodization of the resist film, formation and patterning of the insulating film are not required.

〔Example〕

Figure 1+al~(fl indicates the process of the first embodiment of the present invention, and parts common to those in Figure 3 are given the same reference numerals.) The ITO film 20 is formed by electron beam or sputter deposition method to
A film was formed to a thickness of 2,000 yen, and Cr was deposited on top of it by sputtering.
Film formation 0 was formed to a thickness of 1000 to 2000 layers.

Next, a resist pattern (not shown) is formed by photolithography, and using this as a mask, Cr11130 is etched with a mixture of ceric ammonium nitrate and perchloric acid to form C" film patterns 31, 32, and 35. ,
Subsequently, the ITO film 20 was etched with a mixture of ferric chloride and hydrochloric acid to form a pattern 21°22 identical to that of Cr1lQ.
, 25 was formed (Figure b) 0. Next, 11. After leaving it in the plasma for 5 minutes, plasma C
A-311A40 having a pin junction was deposited on the entire surface using the VD method to a thickness of about 4,000 layers, and then a Cr film 0 was deposited on it using a sputtering method to a thickness of 1,000 to 2,000 layers. In Figure c), a resist pattern (not shown) is deposited on this laminated film using the photolithography method, and the Cr film 0 is deposited on the upper part of the diode using a mixed solution of ceric ammonium nitrate and perchloric acid. Form Cr film patterns 51 and 52 that will serve as electrical connections, and use the resist pattern + Cr1ll pattern as a mask to form a-5t
a-5 of each diode by dry etching
A pattern of tl1141.42 was formed. Dry etching was performed using a mixed gas of SF4 and (:, (JP,
It was conducted under KW conditions. After that, oxygen gas was introduced into the reaction tank, the degree of vacuum was 0.1~0, 5 Torr, and the electric power was 300~I.
The resist film was ashed by discharging under K- conditions (Figure d)
), this result 5. Cr1PJ31゜a -3IIf14
1. A diode 11 made of a Cr film 1, a Cr film 2. a-51 film 42+ A diode 12 is formed by forming a Cr film 2. First, an aluminum film 80 is deposited on the entire surface by sputter deposition to a thickness of 5000 to 1- (Fig. e), and then photolithography is applied thereon. Form a resist pattern (not shown) by the method, HsPOs and HHOs
M wiring patterns 81 and 82 and scanning line patterns 83 were formed by etching with a mixed solution of. Furthermore, by etching with a mixture of ceric ammonium nitrate and perchloric acid, ITO! ul pattern on i 81, 82, 83
．． The untied Cr1L covered with the a-st'B butter 741.42 is removed, and the portion 34. Part 3 below the scanning line 83 from the Cr film formation 2
3 is separated, and on the pixel electrode 25 made of ITO, M is separated.
CrH35 remains only under the wiring 81 (Figure r>
.

This first embodiment has the following advantages.

(The 11th film layer is ITO11A20.Cr film 0.
a-5tll! 140. Cr111150,
Af film 8017) 5Nte, the number of layers is 3 compared to the case in Figure 3.
N decreases.

(Dry etching of 21Cr becomes unnecessary, and problems caused by U radicals to the vacuum evacuation system of the apparatus 1 are eliminated.

(3) SF4 and c with the board mounted on the ground side electrode,
cIF.

Plasma of A-SAG using mixed gas system.

etching, and the equipment is simpler than reactive ion etching.

(4) By using plasma ashing to remove the resist film after forming the diode pattern, each diode's a
The side surfaces of the -3i film are insulated, making it unnecessary to form and pattern a SIN insulating film.

The insulation is thought to be due to oxidation of the side surface of the a-3t film,
This reduces the number of patterning masks from the conventional four to three.

FIG. 4 (at to fdl shows the steps of the second embodiment of the present invention, and the same parts as in FIG. 1 and FIG. 3 are given the same reference numerals. A Cr film 30 with a thickness of 1,000 to 2,000 layers was formed by sputtering (Figure 8).Next, a resist pattern was formed by photolithography, and using this as a mask, the Cr film 30 was coated with ceric nitrate. Form Cr film patterns 31 and 32 by etching with a mixture of ammonium and perchloric acid (Figure b>,
Next, the A-5L film 40 having a pin junction was laminated to a thickness of about 4000 wafers in the same manner as in FIG. A resist pattern is formed using a photolithography method, and upper electrodes 51 and 52 of the diode are formed using a mixture of ceric ammonium nitrate and perchloric acid. 1 A-3ill patterns 41 and 42 of each diode were formed by dry etching under the same conditions as in Figure 1 (d).
Plasma ashing of the resist was performed under the same conditions as in i (Figure c), and finally sputter deposition was performed to obtain a
A resist pattern is formed by photolithography, and etched using a mixture of ferric chloride and hydrochloric acid to form an ITO pixel electrode 25 and the upper Cr electrode 8i51 of the diode 11 connected to it. Contacting ITO wiring 21. Lower part of diode 11 C4tM3
Patterning was carried out for the summer To wire 22 that contacts the upper Cr electrode 52 of the diode 1 and the diode 12 and connects both diodes in series, and the ITO scanning wire 23 that contacts the extension of the C electrode 32.

The advantages of this second embodiment are, in addition to those listed for the first embodiment, as follows.

(1) Cr film formation a The number of layers is 1111 fewer because there are only 4 layers: St film + Cr film + ITO film.

(2) Compared to the first example, the upper Cr film pole did not recede, and the influence on the optical element was reduced.

〔Effect of the invention〕

According to the present invention, after patterning the lower Cr electrode forming the diode by wet etching,
The upper Cr film was layered, and the upper Cr film was patterned using a wet method. After that, the a-3i film was patterned, and the diode was formed by plasma etching in 01 to ash the resist film used for patterning. a of
By insulating the -3l film formation surface, the number of film formation layers is reduced and the number of patterning masks is reduced to three, as well as Cr1
Since dry etching using U-based or F-based gases and reactive ion etching, which require expensive equipment, are not used for patterning the 1100 µm, equipment costs are also reduced, making it possible to manufacture active matrix elements at low cost. Extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the steps of the first embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of a liquid crystal display device using an active matrix substrate equipped with diodes, and FIG. 3 is a diagram of a conventional active matrix. FIG. 4 is a cross-sectional view sequentially showing the steps of the device manufacturing method, and FIG. 4 is a cross-sectional view sequentially showing the steps of the second embodiment of the present invention. 10 Nigarasu group, 20:rTOIQ, 21.22+
ITO wiring, 23+ITO scanning line, 25+ITO pixel electrode, 30, 31.32.50.51.52: Cr
Membrane, 40.41.42: a-51 membrane, 81,82:A
7 wiring, 83: A7 scanning line. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1) When forming the diode of an active matrix element in which amorphous silicon diodes are connected in antiparallel between the scanning line and the data line and are connected in series with the liquid crystal driving electrode, the amorphous silicon diode is placed directly on a transparent insulating substrate or through a transparent conductive film. After patterning the formed chromium film using a wet etching method, an amorphous silicon film and a chromium film are layered on top of it, and the upper chromium film is patterned using a wet etching method using the resist film as a mask to form the upper electrode of each diode. After that, etching is performed using the resist film and the upper chromium film as masks to form an amorphous silicon film pattern for each diode, and the resist film is ashed by plasma etching in an oxygen atmosphere, and the sides of the amorphous silicon film are oxidized. A method for manufacturing an active matrix element for a liquid crystal display, the method comprising forming an insulating film.