JPH0266520A - Manufacture of active matrix element for liquid crystal display - Google Patents

Abstract

PURPOSE:To reduce the cost by adding side etching size to the patterning mask size of an upper layer Cr film when the upper layer Cr film and an a-Si film are patterned and applying an isotropic plasma etching method obtained by mounting a substrate on an earth side. CONSTITUTION:An ITO film 20, a Cr film 30, an a-Si film 40, and a Cr film 50 are formed on the glass substrate 10. Then the substrate is installed at an earth-side electrode and the isotropic plasma etching of the Cr film 50 is carried out to form patterns 51 and 52; and the isotropic plasma etching of the a-Si film 40 is carried out by using the Cr film pattern as a mask to form patterns 41 and 42. Here, a resist pattern is of the size obtained by adding the side etching size values in the Cr film etching and a-Si film etching at the time of the plasma etching. Then patterns 31, 32, and 35 are formed and the same patterns 21, 22, and 25 as the Cr films are formed to constitute a diode 11 composed of the Cr film 31, a-Si film 41, and Cr film 51 and a diode 12 composed of the Cr film 32, a-Si film 42, and Cr film 52. Consequently, the cost is reducible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method in which an amorphous silicon (hereinafter referred to as a-5l) diode connected in antiparallel between a scanning line and a data line is connected in series with a liquid crystal driving electrode. The present invention relates to a method of manufacturing an active matrix element for a liquid crystal display for a 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-51 transistors or diodes have been developed, and products are now on the market. Among these types of devices, those that use diodes have fewer steps and are easier to reduce costs, and they are said to have excellent stability because they are connected in antiparallel to create a ring diode configuration. It has characteristics.

Figure 2 shows an equivalent circuit diagram of an active matrix type liquid crystal display device using diodes.The scanning lines 431 and data lines 2 formed on separate glass substrates form a matrix shape, and by performing matrix scanning drive. The liquid crystals 4 located at the intersections are sequentially driven electrically.The active matrix element is composed of several diodes connected in series and connected in parallel between the liquid crystal driving electrodes at the intersections and the scanning line 1. However, a ring diode 3 is interposed therebetween.

Figure 3 (+1) ~ tel is 2 as shown in the structure shown in Figure θ.
The conventional manufacturing process of an active matrix device with a-5i diodes in series is shown, in figure a, the sho
Soak w? Glass substrate 1 coated by l or sputtering method etc.
iTo formed by vapor deposition or sputtering on
(indium tin oxide), transparent conductive III such as SnJ
J20, approximately 1000 cm thick c using sputtering method
rs 30, pin formed using plasma CVD method
A-Si film 40 about 4000mm thick, with a junction
Cr about 1000mm thick each using sputtering method
A film 50 and an M film 80 having a thickness of approximately 3000 mm are formed.

The pIn junction consists of a p layer approximately 500 μm thick, a single layer (non-doped N) approximately 3000 μm thick, and a 0 layer approximately 500 μm thick, and is made of Cr using photolithography. Membrane 50. a-5l membrane 40. The Cr film 30 is patterned, and the two diodes 11 and 12 are connected to the Cr film 3.
1. aSill! J41. Cr film 51 and Cr film 32
．． a-3t membrane 42. Formed with Cr film 52 (
In this photolithography method, a resist film with a desired diode pattern is formed, and using this as a mask, (Hs P Os + If N O3+ CHs
C00H) Buttering the M film 80 with a solution0
Next, the Cr film 5Q, the a-3i film 40, and the Cr film 30 are patterned by plasma etching using a mask in which this resist film is reinforced with an M film. First, Cc14
A mixed gas of
The Cr film 50 was plasma etched under conditions of ~0.5 Torr and Tl force of 200~100 OW, and then etched with CF and 0.5 Torr. A mixed gas of 0.05 Torr, 1
The a-Sl film 40 is plasma etched under k- conditions, and finally etched again using a mixed gas of CCJ 4 and O2.
．． The Cr film 30 is etched under conditions of 1 to 0.5 Torr and 300 to 700 W.

Next, by photolithography, a transparent conductive film 20 is formed using a resist mask with a mixed solution of ferric chloride and hydrochloric acid.
The transparent electrode patterns 21, 22, 25 are etched.
(Figure cL) After this, SiN 11! for diode protection is formed by plasma CVD method in which a mixed gas of NHl and SiH4 is plasma decomposed, and then SiN 11! is formed for diode protection by plasma etching using a mixed gas of SFb and C, CJ ps. SiN film pattern 61 by photolithography method
, 62.63 (Figure d), and then use a sputtering method to form a Cr film with a thickness of 1000 nm and a Cr film with a thickness of 5000 ~1
A metal film consisting of 2!1i of A7 film with a thickness of - is laminated,
By photolithography, M contains H, PO, and HN.
Wiring metal film patterns 71, 72, and 73 are formed using a mixed solution of O3 as an etching solution and a mixed solution of ceric ammonium nitrate and perchloric acid as an etching solution for Cr. As a result, the diode 11 and the diode 12 are connected in series and inserted between the pixel electrode 25 and the scanning line 73 (FIG. e).

The reason why a laminated film of a Cr film and an M film is used as the metal film is to prevent the atmosphere during etching of M from damaging the ITO film.

[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 film layers are ITO film 20. Cr film 3Q, a-5
i membrane 40. Cr film 501M film 80. Crl! for the SiN film (forming patterns 61, 62.63) and bilayer III (forming patterns 71, 72, 73). l,Aj
There will be as many as 8 layers of membrane.

(2) Cr film 50 for forming diodes 11 and 12
．． 'a-3i membrane 40. When patterning the three layers of the Cr film 30 by plasma etching, it is necessary to set the conditions to a highly anisotropic reactive ion etching mode so that no eaves are left due to side etching. There is a problem in that the workpiece must be transported on the ground side and must be moved to the opposite pole 1i during etching.

(3) The ceric ammonium nitrate used to form the wiring metal film patterns 71, 72, and 73 is expensive.

In addition, since the wiring film is formed of two layers of Cr and 11, the side etching of the wiring becomes large, and the side etching of Cr is even larger, forming an M-shape, which makes it difficult to clean with wet processing agents such as etching solution. It tends to be insufficient and contaminants are likely to remain on the surface.

The object of the present invention is to pattern the C film and a-S+ film that constitute the diode with the workpiece on the ground side, and to form a wiring pattern without an overhang without using ceric ammonium nitrate. An object of the present invention is to provide a low-cost method of manufacturing an active matrix element for liquid crystal display.

[Means to solve the problem]

In order to solve the above problem, the present invention provides an active matrix device in which A-3L diodes connected in anti-parallel between scanning lines and data lines are connected in series with a liquid crystal drive bridge. In, lower Cr! l! ! ! , a-
The 3i film and the upper NCr film are laminated, and the upper Cr film is patterned by isotropic plasma etching to a size larger than that of a predetermined diode, and then the a-3ill is patterned by isotropic plasma etching using the upper Cr film pattern as a mask. The predetermined diode dimensions shall be obtained by etching and side etching. In addition, the upper layer Cr film + a
Lower JiCr that forms a diode with S i @
Butter the transparent grooves on the membrane in the same pattern as the membrane, and
The M wiring that contacts the lCr film through the opening of the insulating film and forms the connection wiring between the diode and the pixel electrode made of a transparent conductive film, the connection wiring between the diodes, and the scanning line and data line is patterned from the M film. After that, the portion of the lower Cr film that is not covered by the insulating film and the A7 film is removed by isotropic plasma etching.

[Effect]

At least when patterning the upper NCr film and the a-5t film, an isotropic plasma etching method in which the substrate is mounted on the ground side can be applied by adding a side etching amount to the patterning mask dimensions of the upper JiCr film. Furthermore, by leaving the lower layer Cr1l until the time of M wiring patterning, the transparent conductive film is not damaged during M etching without using a kl-Cr double layer wiring, and no M overhang is formed.

All buttering and removal of the Cr film is performed by isotropic plasma etching, making it unnecessary to use an expensive Cr111 etching solution.

〔Example〕

Figures 1 fa) to le) show the steps of an embodiment of the present invention, and parts common to those in Figure 3 are denoted by the same reference numerals.
In FIG.
A film was formed to a thickness of 0.00 mm, and then a Cr film 3 was deposited on it by sputtering.
The p
An a-Sl film 40 having an in-junction is formed to a thickness of approximately 0.4 mm using a glow discharge method, and a Cr film 50 is formed thereon to a thickness of 1000 to 2000 mm using a sputtering method. did.

After that, a resist pattern (not shown) is formed by photolithography, the substrate is placed on the ground electrode, and the vacuum level is 0.1-0.5 Torr and the power is 200-10'.
cr using a mixed gas of CC1 and 0□ under OOW conditions.
Perform sso isotropic plasma etching to create pattern 5.
1.52 was formed.Then, using the resist pattern and Cr1l pattern as a mask, the degree of vacuum was 0.1 to 0.5.
A-3i film 4 was formed using a mixed gas of SF4 and CI Cj F s under conditions of Torr and power of 200 to 100 OW.
0 isotropic plasma etching, pattern 41.42
(Figure b). In this case, side etching occurs due to isotropic etching, so the resist pattern is different from that of the Cr film during plasma etching and the aSi etching.
The dimensions are made larger by the addition of side etching during film etching.Next, a resist pattern (not shown) is formed again, and using this as a mask, the Cr film 30 is exposed to a vacuum degree of 0.1 to 0.5 Torr. 200~100O
Isotropic plasma etching was performed using a mixed gas of CCT and 08 under conditions of W to form patterns 31, 32, and 35. Furthermore, the ITO film 20 is etched with a mixture of ferric chloride and hydrochloric acid to form the same pattern 21, 22 as the Cr film.
．． 25 was formed (Figure C). As a result, the Cr film 31.
a-Sl film 41. Diode 1 made of Cr film 51
1, and a Cr film 32. a-3t membrane 42. Cr film 52
A diode 12 is made up of 0-order NHs of 5
The SiN film is formed into a 0.3 to 1-
The Cr film 31,
with an opening above 51.32.52 and a diode 11
．． SiN film patterns 61, 62 and 63 were formed to cover the side surfaces of 12 (Fig.
A resist pattern (not shown) is formed by photolithography, and H,
Diode 1 was etched with a mixture of PO and HNO3.
A wiring 81 connecting the Cr film 51 of No. 1 and the pixel to the pole 25. Cr film 31 of diode 11 and Cr film 5 of diode 12
2 and the Cr film 32.
and 63 formed a pattern of scanning lines 83 in contact with the openings between them.
Isotropic plasma etching was performed using a mixed gas of CCl2 and 0° under the conditions of an electrode force of 200 to 1000 W to remove the portion of the Cr film 35 that was not covered by the A7 film and the SiN film (Figure e). , pixel electric bridge 2 made of ITO
5, the Cr film 35 remains only in the portion below the M wiring 81. Note that the remaining resist was removed using a wet remover.

The above embodiment has the following advantages.

+1) The film forming layer is an ITO film 20. Cr1I130.
a-5i membrane 40. Cr film 50. SiN film (61,
62, 63), the Aj film 80 has six layers, which reduces the number of layers by two compared to the conventional example shown in FIG.

(All the 21Cr layers are buttered or removed by plasma etching and are unified, and no wet etching is performed, eliminating the need for expensive etching solutions.

(Since no 31AI-Cr wiring is used, there is no M overhang, no etching solution remains on the surface, and display defects caused by interaction with liquid crystal in subsequent steps are eliminated.

(4) Since isotropic plasma etching is used instead of anisotropic reactive ion etching, etching can be performed with the substrate mounted on the grounded electrode, which simplifies the apparatus.

In the above embodiment, Figure 1! S who explained about d)
The conditions for forming the iN film were changed as follows. That is,
After vacuum evacuation, introduce nitrogen gas, 0.1~Q, 5 To
After creating a nitrogen atmosphere of rr, NH and SiH* were additionally introduced, the vacuum degree was 0.1 to 0.5 Torr, and the power was 30
A film was formed by performing discharge under the conditions of 0 to 100 OW. Furthermore, the film formation process was varied individually for each loft, and the results of examining leakage defects at low voltage for each loft are shown in Table 1. After that, a discharge was performed for 1 to 10 minutes in an atmosphere in which 5ila and %I* were added to nitrogen.

Table 1: When the SiN film was formed by plasma decomposition of a mixed gas of NH3 and SiH4 as in the above example, the IJ-reflection defect was 30%, but the first result was that it was significantly improved. This can be seen from the table. It can also be seen that it is more effective to introduce only nitrogen initially for a longer period of time, and to perform discharge at that time as well.

Furthermore, in addition to this, a-5ill! After patterning by plasma etching in step 40, oxygen gas was introduced into the reaction tank and the vacuum was 0.1 to 0.5 Torr and the power was 300.
When the resist was ashed by discharging under the conditions of ~iooow, leak defects almost disappeared. The resist pattern used for buttering the SiN film and the M film can also be removed by ashing in Ot gas by switching the gas. This is done only after buttering by etching the film 20, which saves consumption of stripping solution.

4(a) to ffl show steps of different embodiments of the present invention, and the same parts as in FIG. 3 are given the same reference numerals. In FIG.
A resist pattern (not shown) is formed by a 0-order photolithography method on which a Cr film 0 is formed by sputtering to a thickness of 1000 to 2000 nm. Using as a mask, deposit 0 Cr film at a vacuum level of 0.1 to 0.5 Torr and a power of 200 to 1000.
Plasma etching is performed using a mixed gas of CC14 and 0□ under W conditions to form CrWX patterns 31, 32, and 35, and then the IT○ film 20 is etched with a mixture of ferric chloride and hydrochloric acid to form a Cr film. Same pattern as 21.2
2.25 was formed (Figure b) 0. Next, the reaction layer was left in an 11t plasma generated under the conditions of a vacuum of 0.1 to I Torr and a power of 500 W to IK for 5 minutes, and then the plasma CV
An a-Sl film 40 having a pin junction is formed on the entire surface using the D method to a thickness of approximately 4000 nm, and then a Cr film 0 is evaporated thereon to a thickness of 1000 to 2000 nm using a sputtering method. (Fig. c), a resist pattern (not shown) whose dimensions were enlarged by the side etching was deposited on this laminated film using a photolithography method, and the vacuum degree was 0.
1 to 0.5 Torr, ii CCJ under the conditions of force 200 to 100 OW, and 0. Using a mixed gas of l SP only the gas using the Cr film pattern as a mask.
The a-3t film was isotropically plasma etched using a mixed gas of , +C, CZF, and the same conditions to form an a-5tl141.42 pattern for each diode.

After that, oxygen gas is introduced into the reaction tank and the degree of vacuum is 0.1 to 0.
The resist film was ashed by discharging at 5 Torr and a force of 300 to IK- (Fig. d). As a result,
Cr film 31°a-3i film 41. A diode 11 made of a Cr film 51, a Cr film 32. a-3t membrane 42.
0 where the diode 12 made of Cr11952 is constructed
Next, an aluminum film 80 is deposited on the entire surface by sputter deposition.
A resist pattern (not shown) is formed on it by photolithography, and etched with a mixture of H, PO, and HNOs.
A wiring pattern 8L82 and a scanning line pattern 83 were formed. Furthermore, the degree of vacuum is 0.1 to 0.5 Torr, Tl
I
M film pattern on TO film 81°82.83. a-3i
The Cr film not covered by the film patterns 41 and 42 is removed, and the portion 34° below the M wiring 82 from the Cr film 31 is removed from the Cr film 3.
The portion 33 below the scanning line 83 is separated from 2, and the Crtl 135 remains only in the portion below the beam wiring 81 on the pixel electrode 25 made of ITO (FIG. f).

This embodiment has the advantage (2) of the previous embodiment.

+31. (In addition to 41, there are the following advantages.

(1) The film formation layer is IT Ol! ! 20. Cr film formation 0,
a-5lll14Q, Cr film formation 0. When the A7 film 80 is 5N, the number of layers is reduced by three layers compared to the case of FIG.

(2) By using plasma ashing to remove the resist film after forming the diode pattern, the a
The side surfaces of the −5i film are insulated, and S+N&f! Edge film formation and buttering are no longer necessary.

The insulation is thought to be due to the oxidation of the side surface of the a-31 film, but
This reduces the number of patterning masks from the conventional four to three.

〔Effect of the invention〕

According to the present invention, by expanding the etching mask in consideration of the side etching, it is possible to perform patterning using isotropic plasma etching, which allows the substrate to be mounted on the ground side, and the etching equipment has become simpler. . Furthermore, by leaving the Cr film used as the lower layer of the diode and forming an M film wiring pattern, and removing the unnecessary Cr film by dry etching, it is possible to eliminate the overhang that occurs when using AI-Cr two-layer wiring. , surface cleanliness was improved, and defects caused by interaction with liquid crystals were prevented. Further, an expensive etching solution for Cr is not required, which is also effective in reducing costs.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the steps of an 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 conventional method for manufacturing an active matrix element. FIG. 4 is a cross-sectional view sequentially showing the steps of the method; FIG. 4 is a cross-sectional view sequentially showing the steps of different embodiments of the present invention. 10 glass substrate, 11.12: diode, 20:■
TO film, 25: ITO pixel electric bridge 0.31.32.3
5°50, 51.52: Cr film, 40.4L 42:
a-3t film, 80:A! Film, 81, 82: Aj wiring,
83: A7 scanning line. Figure 2 Figure 1 Figure 3

Claims (2)

[Claims] (1) When forming a diode of an active matrix element in which amorphous silicon diodes connected in antiparallel between scanning lines and data lines are connected in series with liquid crystal driving electrodes, a lower chromium film, an amorphous silicon film, and an upper chromium film are The upper layer chromium film is patterned by isotropic plasma etching to a size larger than the predetermined diode, then the amorphous silicon film is patterned by isotropic plasma etching using the upper layer chromium film pattern as a mask, and side etching is performed to form the predetermined diode. A method for manufacturing an active matrix element for a liquid crystal display, characterized by obtaining diode dimensions. (2) When forming a diode of an active matrix element in which antiparallel amorphous silicon diodes are connected in series with a liquid crystal driving electrode between a scanning line and a data line,
The lower chromium film, which together with the upper chromium film and the amorphous silicon film constitutes the diode, is patterned in the same pattern as the transparent conductive film, and is brought into contact with the upper chromium film through an opening in the insulating film, forming a pixel electrode consisting of the diode and the transparent conductive film. After patterning the aluminum wiring that forms the connection wiring between the diodes and the diodes as well as the scanning line and data line from the aluminum film, isotropic plasma etching is performed on the parts of the lower chromium film that are not covered by the insulating film and the aluminum film. A method for producing an active matrix element for a liquid crystal display, characterized in that the active matrix element is removed by removing the active matrix element.