JPH01224725A - Active matrix element for liquid crystal display - Google Patents

Abstract

PURPOSE:To reduce the cost of an etching device to obtain a low-cost active matrix element for liquid crystal display by preventing the same pattern from being given to three layers of a diode consisting of an a-Si film and a Cr double- faced electrode and extending the Cr film pattern of the substrate-side electrode and using this pattern for connection to another diode or a scanning line. CONSTITUTION:With respect to the active matrix element where a-Si diodes of anti-parallel connection are connected in series to a liquid crystal driving electrode between the scanning line and a data line, a-Si diodes 11 and 12 consist of a Cr film 30, an a-Si film 40, and a Cr film 50 laminated on a transparent insulating substrate 10. The Cr film 50 more distant from the substrate 10 and the Cr film 30 under the a-Si film 40 are extended and are brought into contact with wirings 81 and 82 for connection to another diode and a scanning line 83. Thus, the active matrix element for liquid crystal display is obtained which has a small number of formed film layers and does not require reactive ion etching using gaseous Cl.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an amorphous silicon (hereinafter referred to as a-51) diode connected in antiparallel between a scanning line and a data line, connected in series with a liquid crystal driving electrode. The present invention relates to an active matrix element for liquid crystal displays for liquid crystal televisions and the like.

[Conventional technology]

In order to improve the image quality of liquid crystal televisions, active matrix driven liquid crystal televisions using a-3l transistors or diodes have been developed, and products are now on the market. Among these types of devices, those that use diodes require fewer steps and are cost effective, and they also have excellent stability because they connect diodes in antiparallel to create a ring diode configuration. There is a characteristic that.

Fig. 2 shows an equivalent circuit diagram of an active matrix type liquid crystal display device using diodes. The liquid crystals 4 present in the display are sequentially driven electrically. The active matrix element has a ring diode 3 interposed between the liquid crystal driving electrode and the scanning line l, which are intersecting points, by connecting several series-connected diodes in parallel.

Figures 3 (5) and 3 (6) show the manufacturing process of an active matrix element having two series A-3L diodes as shown in the conventional structure shown in Figure e; Alternatively, a transparent conductive material such as ITO (indium tin oxide), Snug, etc., formed by vapor deposition or sputtering on a glass substrate 10 in which 8108 is coated on soda glass by dipping or sputtering, etc., is used. A Cr film with a thickness of approximately 1,000 mm is deposited.
A-3illQ40 with a thickness of about 4,000 with a pin junction formed using plasma CVD, Cr film 0 with a thickness of about 1,000 and AJ#80 with a thickness of about 3,000 using sputtering, respectively. was formed. pin
The bonding was performed using a pH of approximately 500 μm thick, a pH of approximately 3000 μm thick, 1 [(non-doped 71) and a pH of approximately 500 μm thick.
The zero-order layer consists of Cr using photolithography method.
Film formation 0. a-5t membrane 40. The Cr film 0 is patterned, and the two diodes 11.12 are formed with a Cr film 31.
a-3iIIa41°Cr film 51 and Cr film 32.
a-3ill! 42. Formed with Cr film 52 (Figure b)
), in this photolithography method, a resist film with a desired diode pattern is formed, and using this as a mask, first, the M film 80 is patterned with a (lhPO, + HNO, + CHsCOOll) solution. CrU3O,a-51Wi40. Patterning of Cr film 0 is performed. First, Cr1l beauty 50 is CC74
A mixed gas of
Plasma etching was performed under the conditions of 0.5 Torr and power of 200 to 100 OW, followed by CF and 0.5 Torr. A mixed gas of 0.05 Torr was introduced.

Plasma etching is performed on a-SllIQ40 under lk- conditions, and finally, etching of the Cr film 0 is performed again using a mixed gas of CCl4 and 01 under conditions of 0.1 to 0, 5 Torr, and 300 to 700 W.

Next, by photolithography, a transparent R electrical film 20 is formed using a resist mask and a mixed solution of ferric chloride and hydrochloric acid.
The transparent electrode patterns 21, 22, 25 are etched.
(Figure cL After this, N111 and Sl!
A SiN film for protecting the diode was formed by plasma CVD method in which a mixed gas of 14 was decomposed by plasma, and SF, and C
SIN film patterns 761, 6 are formed by photolithography using plasma etching using a mixed gas of C7F.
2.63 is formed (Figure d), and then a metal film consisting of two layers, a Cr film with a thickness of 1000 mm and an AIWA film with a thickness of 5000 mm to 1 mm, is further laminated using a sputtering method, and then a metal film is formed using a photolithography method. Metal film pattern? 1,72.73 is formed. As a result, diode 11 and diode 12
are connected in series and inserted between the pixel electrode 25 and the scanning line 73.
Pa is used because the atmosphere during etching of M is t.
This is to prevent damage to the TOM1.

[Problem to be solved by the invention]

The conventional manufacturing process of the active matrix element for liquid crystal display explained in FIG. 3 has the following problems.

(11 formation wili fJ < [T O @ 20. Cr film formation 0. a -5L) 1340. Cr film formation 0. A
7 membranes 80. There are 8 layers of Cr film and A7 film for SiN film (forming patterns 61, 62.63) and 2N film (forming pattern ?1, 72.73).

(2) Cr film is formed to form diodes 11 and 12.
．． a-St film 40. When patterning the three layers of Cr1lQ30 by plasma etching, it is necessary to use a reactive ion etching mode with strong anisotropy in order to prevent side etching from forming an overhang. However, it is necessary to mount the substrate on the electrode opposite to the ground side, which causes many problems with the etching equipment.

Due to CCl2 used for etching +31Cr, α
There is a limitation that stainless steel cannot be used for equipment because radicals are generated and corrode Cr, and a
As this causes the oil in the vacuum pump to deteriorate, countermeasures are required.

An object of the present invention is to eliminate the above-mentioned problems and provide an active matrix element for a liquid crystal display that requires a small number of film formation cycles (and does not require reactive ion etching using a CJ-based gas).

[Means to solve the problem]

In order to solve the above problems, the present invention provides an active matrix element in which an anti-parallel A-5T diode is connected in series with a liquid crystal driving electrode between a scanning line and a data line, and the A-5L diode is connected in series with a liquid crystal driving electrode. A-stlla is a Cr film laminated on a transparent insulating substrate.

Cr film on the side far from the substrate and a-5
It is assumed that the Cr film under the i-film is extended to contact wiring and scanning lines for connection with other diodes.

[Effect]

In the a-Sl diode, only the upper two layers have the same pattern, and there is no need to pattern the three layers simultaneously by anisotropic dry etching, so an M mask is not required, and the lower Cr
Etching of the film can be done by wet etching, so no U-based etching agent is required.Also, when patterning M wiring, even if there is a transparent conductive film on a transparent insulating substrate, the long part of the Cr film is formed on it. Since it can be interposed, Cr
There is no need to form a separate film, or the transparent conductive film that forms the liquid crystal drive electrode can be used not under the lower Cr film but between the diodes and for connection to the liquid crystal drive electrode, so the number of layers required can be reduced. decreases by 2JlI or 3 layers.

〔Example〕

1 fa) to tel show the manufacturing process of the active matrix element of the first embodiment of the present invention, and in FIG. 0 a, parts common to those in FIG.
On the glass substrate 10, rTOli 120 is deposited to a thickness of 1,000 to 2,000 layers by electron beam or sputter deposition, and a Cr film 0 is deposited to a thickness of 1,000 to 2,000 layers by sputtering.
A-Sl11140 having a pin junction was sequentially formed to a thickness of about 4000 mm using a plasma CVD method, and finally a Cr film 0 was formed to a thickness of 1000 to 2000 mm using a sputtering method. Unlike the case in Figure 3, A711!
No film is formed at 80, and a pin junction is formed in the a-3i film in the same way as in the case of FIG. 50 is etched with a mixed solution of ceric ammonium nitrate and perchloric acid to form a Cr1g pattern 51.52, and then a-3i is formed using the Cr film pattern and the resist pattern above it as a mask.
# was patterned by dry etching. Dry etching uses a mixed gas of SF and C1CfFs, and the degree of vacuum is 0.
．． The test was carried out under the conditions of 1 to 0.5 Torr and power of 200 W to IK-. As a result, a-Sl film patterns 41 and 42 having the same dimensions as the Cr film patterns 51 and 52 were formed (Fig. b
), a resist pattern is further formed by photolithography, and Crl! 30 is etched again with a mixture of ceric ammonium nitrate and perchloric acid to form Cr film patterns 51, 52. a-Cr film patterns 31, 32, and 35 larger than the Sl film patterns 41 and 42 are formed, and I
The TO film 20 was etched with a mixture of ferric chloride and hydrochloric acid to form ITO film patterns 21, 22, and 25 having the same dimensions as the Cr film patterns 31, 32, and 35. Cr film formed 1°a-Sl film 41. Cr film 1 is diode 11
．． Cr film formation2. a-51 membrane 42. The Cr film 2 constitutes the diode 12 (Figure cL, then IIH, and S I
Plasma CV for plasma decomposition of mixed gas of I+
A SiN film is formed by the D method, and a SiN film is formed using the photolithography method to have an opening on the Cr11!131.51,32.52) and cover the side surface of the diode 11.12.
Film patterns 61, 62 and 63 were formed (Figure d)
.

For etching, dry etching using SPh, CRC7F, and gas was performed under the same conditions as in the case of the a-3l film. After that, an M film is deposited by sputtering to a thickness of 500 to 1 μ-, and a wiring 8 connecting the Cr film 1 of the diode 11 and the pixel electrode 25 is formed using a photolithography method.
1. Cr film 1 of diode 11 and C of diode 12
SiN is applied to the wiring 82 connecting the r film 2 and Cr#32.
A pattern of scan lines 83 was formed that contacted the openings between membranes 62 and 63. Subsequently, the exposed Cr film was etched using a mixed solution of ceric ammonium nitrate and perchloric acid. As a result, the C film 3 on the pixel electrode 25
5 is removed, and the Cr film pattern 35 has an M arrangement 81.
and was only interposed at the connection portion of the pixel electrode 25 (Fig. e).

The above embodiment has the following advantages.

(The 11th film layer is ITO film 20+ Cr film 0+ a
St film 40. Cr film formation 0. SiN film (patterns 61, 62, and 63 formed) and AI film (pattern 8
1, 82, 83), and the number of layers is reduced by two layers compared to the conventional example shown in FIG.

f2) Since Cr dry etching is not performed, CC1
U radicals generated from a solve problems that occur in equipment, evacuation systems, etc.

(3) Since plasma etching in reactive ion etching mode is not required, the element substrate is mounted on the ground side electrode, and SF4 and C! It becomes possible to etch the a-3i film and the SiN film using a mixed gas system of clFs, which simplifies the etching equipment.

14) By making the Cr film pattern 31.32 larger than the a-51 film pattern 41.42 and the M film pattern 81.82 covering the a-3l film pattern 41.42, the a-3i film of the diode is When assembled into a television set, leakage caused by the generation of photovoltaic force in the diode due to the incidence of light is suppressed, and clear images can be obtained.

FIG. 4 (al to (el) shows the manufacturing process of the active matrix element of the second embodiment of the present invention; FIG.

Components common to those in FIG. 3 are given the same reference numerals. In figure a, carbon is deposited on a glass substrate 10 by sputtering.
1,000 to 2,000 people to form r film 0, and about 4,000 people to form a-5t film 40 with pin junction by plasma CVD method.
CrtI! 50 to 1000
Figure 1 shows the nine layers formed and laminated to a thickness of ~2,000 layers.
From r film formation 0, patterns 51 and 52 are formed using a mixture of ceric ammonium nitrate and perchloric acid, and SFh, C, cl.
a-5 by dry etching using a mixed gas of lls.
Patterns 41 and 42 were formed from illi40 (Fig. b
), a resist pattern was further formed by photolithography, and Cra 30 was etched again using a mixture of ceric ammonium nitrate and perchloric acid to form Cr1ll patterns 51, 52 and a-51 film patterns of the same dimensions. crll greater than 41.42! 2 patterns 31
．． 32 was formed, resulting in the formation of diodes 11 and 12 (Figure c) a. In the next step, N1 (3 and SIH
A SIN 1lfi film is formed by a plasma CVD method that plasma decomposes the mixed gas of *, and a 5il film is formed using a photolithography method to form openings on Cr1J31, 51, and 32.52, respectively, and cover the sides of the diodes 11 and 12.
IP! Patterns 61, 62 and 63 were formed.
(Figure d), in this case, pattern 61 is pixel 1! S covering the polar surface
It is continuous with the IN film pattern 65. Etching is SF
a-Silli40 using h and Cs CJ p s
A film of ITO11K was formed to a thickness of 1,000 to 3,000 wafers using the zero sputtering method performed under the same patterning conditions as in the previous patterning, and then using the photolithography method. ITo film butter y23, 24, 25, 26 was formed (Figure eL film pattern 3 is connected to the pixel electrode 25 and becomes the wiring connecting the diode 11 to the pixel electrode. The pattern 24 is the Cr1131 of the diode 11 and the Cr of the diode 12. Film formation 2
This is the wiring that connects. The pattern 26 forms a scanning line and is connected to the Cr film 2 of the diode 12.

This embodiment has the following advantages.

(1) The number of deposited layers is Cr1li30. a −3i[4
0, Cr1E150. SiN film (patterns 61, 62 .
63.65) and ITOllA (pattern 23
．． 24, 25, and 26), which further reduces the calendar number by one layer compared to the first embodiment.

(2) Similar to the first embodiment, dry etching using Cr CCIa is unnecessary.

(3) SIN @ patterns 62 and 6 that transmit light
By covering the entire exposed surface of the glass substrate 1 with 5, it is possible to omit coating with the 5ift film even when soda glass is used for the glass substrate.

141 Cr 181 pattern 31, 32 a-5t
By making the film pattern larger than 41 and 42, the incident light through the glass substrate l is
The effect of entering the system is greatly suppressed. The incidence of light from the top surface can be countered by forming a black mask on the counter electrode substrate side, which suppresses the generation of photovoltaic force in the diode due to the incidence of light when assembled into a TV center, resulting in a clear image.

〔Effect of the invention〕

According to the present invention, the three layers of the diode consisting of the a-Si film and the Cr double-sided electrodes are not made into the same pattern, but the Cr film pattern of the substrate side electrode is extended to make it larger, so that it can be connected to other diodes or scanning lines. By utilizing this method, the number of deposited layers can be reduced and dry etching of the Cr film can be omitted, resulting in a low-cost etching device and a low-cost active matrix element for liquid crystal display.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view sequentially showing the manufacturing process of an active matrix element according to a first embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of a liquid crystal display device using an active matrix substrate, and FIG. 3 is a conventional active matrix device. FIG. 4 is a sectional view sequentially showing the manufacturing process of a matrix element. FIG. 4 is a sectional view 1111 showing the manufacturing process of an active matrix element of the second embodiment of the present invention. 10:2 glass substrate, 11:12j diode, 20:I
TOIII, 23.24: I To wiring, 25: I
TO@Elementary electrode, 26: ITO scanning line, 30.31.32
．． 50.51°52: Cr film, 40.41.42=a-
Sill! , 81, 82: kI wiring, 83: M scanning line. Do-)・. Agent 4rJX1- Gen Yamaguchi, Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1) In a device in which amorphous silicon diodes connected in antiparallel between scanning lines and data lines are connected in series with liquid crystal driving electrodes, the amorphous silicon diodes stacked on a transparent insulating substrate are made of a chromium film, an amorphous silicon film, and a chromium film. for a liquid crystal display, characterized in that the chromium film on the side farther from the substrate and the chromium film below the amorphous silicon film are extended to contact wiring and scanning lines for connecting with other diodes. Active matrix element.