JPS62262890A - Manufacture of active matrix element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a method of manufacturing an active matrix element used for driving a display device such as a liquid crystal display.

[Prior art and its problems]

Thin display devices such as liquid crystal displays are used in large quantities as display devices for small electronic devices such as calculators and watches, but the current goal is to increase the size of the display screen and improve the image quality. When performing high-quality display on a large screen, an active matrix method in which each pixel of the screen is provided with a switching element is effective. Thin film transistors (
TPT) and other three-terminal elements and MIM (metal-insulator-
Two-terminal nonlinear elements such as metal) elements, varistors, and diodes have been proposed.In particular, two-terminal nonlinear elements have a simple structure, so they are cheaper to manufacture than active matrix systems using three-terminal elements. Are better. - As an example, a display device using a nonlinear element using a diode is described in Japanese Patent Laid-Open No. 59-57273. In active matrix display devices, in order to improve display characteristics, it is necessary to increase the aperture ratio of the display screen and reduce the capacitance of the switching elements, so it is necessary to form switching elements with small areas at high density on the substrate. required. For this reason, when manufacturing switching elements, a microfabrication technique is required that involves repeating a photolithography process for accurately positioning and patterning a pattern on a photomask. However, in the conventional active matrix method using nonlinear elements, a large number of photomasks are used to form patterns in the manufacturing process of the nonlinear elements, and therefore the photolithography process, which requires high-precision microfabrication technology, is repeated. Since the number of times is increased, there is a problem that the yield decreases and as a result, the cost increases. Below, we will discuss the problems of the conventional nonlinear element manufacturing process.
This will be explained in detail with reference to the drawings. FIG. 3 (al to tel) shows the manufacturing process of a nonlinear element using a conventional diode. A transparent conductive layer is deposited on a glass substrate 1, and a pixel electrode 21 and a scanning electrode 22 are formed using a first photomask. (Figure 3(a)),
Next, the first electrode layer 30. An amorphous silicon layer 40 and a second electrode layer 50 are formed (Fig. 3)), and a second photomask is used to form the first electrode layer 30. By patterning the amorphous silicon layer 40 and the second electrode layer 50, the first electrode 3. Amorphous silicon region 41
A diode 6 consisting of the second electrode 5 is formed (FIG. 3(C)). Next, an insulating film is deposited and the insulating film 7 is patterned using a third photomask so as to form a contact hole 8 above the diode 6, as shown in FIG.
Then, a wiring electrode layer is formed, and the wiring electrode 9 is patterned using a fourth photomask (FIG. 3(e)). In this way, the conventional manufacturing method requires four types of photomasks, and these four types of photomasks are used sequentially.
Since it is necessary to repeat the photolithography process for highly accurate positioning and microfabrication, the yield decreases and, as a result, the cost increases. For this reason, the conventional active matrix method using nonlinear elements has not been put to practical use in large-screen, high-quality display devices.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an active matrix element that solves the conventional problems, has a simple manufacturing process, uses fewer types of photomasks, and can be used for large-screen, high-quality display devices.

[Key points of the invention]

The present invention provides a transparent conductive layer, an i-th pole layer,
After laminating the semiconductor layer and the second electrode layer, a step of sequentially patterning the second electrode layer, the semiconductor layer, the first electrode layer, and the transparent conductive layer in the same pattern as the pixel electrode and the scanning electrode using the first photomask. A process of depositing an insulating film and patterning the insulating film by photoetching using exposure through the substrate, and sequential patterning using a second photomask to form nonlinear elements on the pixel electrode and the scanning electrode, respectively. forming at least a second electrode and a semiconductor layer, and depositing a wiring electrode layer and patterning it using a third photomask to form wiring electrodes that connect the nonlinear element to the scanning electrode and the pixel electrode, respectively. It includes the step of forming,
The above objective is achieved because no more than three types of photomasks are required.

[Embodiments of the invention]

FIG. 2 is a plan view of an active matrix element manufactured according to the present invention, and FIG. The same parts as in FIG. 3 are given the same reference numerals. First, 170 layers with a thickness of 700 mm and 20 mm are deposited on a glass substrate 1 by sputtering. Film thickness: 100 mm by vacuum evaporation method
0 Cr layer 30. Film thickness: 500 mm by plasma CVD method
After forming an amorphous silicon layer 40 with a thickness of 1000 and a Cr layer 50 with a thickness of 1000 by vacuum evaporation (see FIG.
By plasma etching the amorphous silicon layer 40 using CF, 02 gas, and CCl4 and 0□ gas for the Cr layer 30,
Further, the pixel electrode 21 and the Cr layer 31 with the same pattern as the pixel electrode 21 are etched by wet etching using an aqueous solution of ferric chloride and hydrochloric acid. Amorphous silicon layer 41. Cr layer 51, scanning electrode 22, and Cr layer 32 with the same pattern. Amorphous silicon layer 42. Form a Cr layer 52 (Fig. 1(b)
). After forming the film 70 and depositing the negative resist film 10, the light 11 is irradiated from the glass substrate 1 side, and the negative resist 10 is exposed using the Cr layers 31 and 32 formed in the first patterning as a mask. Figure 1 (C)). When the negative resist 10 is developed after exposure, the pixel electrode 21. Negative resist 10 remains on the area other than on the scanning electrode 22, and using this negative resist as a mask, the Si3N4 film 70 is patterned by plasma etching using CF4 and 0□ gas, and the pixel electrode 21. The 5iJ4 film 71 remains in areas other than the pattern of the scanning electrode 22 (FIG. 1(d)). Next, a pattern of the resist 12 is formed using a second photomask, and the Cr layer 5L is formed using the resist 12 as a mask.
52 uses CC1 and 0□ gases, and the amorphous silicon layers 41 and 42 use CF and 0□ gases to pattern the Cr electrode 5 and amorphous silicon region 4 of the diode element 6 by plasma etching. This amorphous silicon layer is etched with CF4 and 0.00% during plasma etching. At the same time, the portions of the 5izNa film 71 that are not covered by the pattern of the resist 12 are also removed by plasma etching, and the insulating film 7 in the pattern shown in FIG. 2 is formed (FIG. 1(e)). Finally, an A1 layer with a thickness of 1p is formed by sputtering, and a third photoI layer is formed.
- Using a mask, wet etching is performed using a mixture of nitric acid and acetic acid to form the wiring electrode 9, and the Cr layer 31 is plasma etched using CCl4 and 0□ gas to form the lower Cr electrode 3 and the diode element 6. The Cr layer 33 on the scanning electrode 21 is patterned (FIG. 1(f)). The diode element 6 is formed in the shaded area in FIG. 2, where the pattern of the first photomask and the pattern of the second photomask overlap,
As shown in FIG. 2, they are connected in parallel and in the opposite direction to the elements formed on the pixel electrode 21 in the same way. The element formed on the scanning electrode 22 shown in FIG. 1 is connected to the pixel electrode 21 by a wiring electrode 9 that contacts the upper Cr electrode 5 and the Cr layer 33. As described above, in the manufacturing method according to the present invention,
Since only three types of photomasks are used, the manufacturing process is simplified. FIG. 4 (al~(C1) is a sequential view showing the manufacturing process of the second embodiment. In this embodiment, photosensitive polyimide is used as the insulating film 72. As the photosensitive polyimide, Hitachi Chemical product name P
L-1,100, East product name Photonice UR3100
Or Merck's product name Selectirasox HTR-2
etc. can be used. The second electrode layer, the semiconductor layer, the first electrode layer and the transparent conductive layer are patterned using the first photomask to form the second electrode layer 51.52) Semiconductor layer 41.42
．． The first electrode layer 31.32 is connected to the pixel electrode 21. Scanning electrode 22
After forming the same pattern as the photosensitive polyimide film 7
2 is formed by a spin coating method, and the glass substrate 1
Light 11 is irradiated from the side, and the photosensitive polyimide is exposed using the patterned first electrode layers 31 and 32 as a mask (FIG. 4(a)). When the photosensitive polyimide is developed with a developer, the pixel electrode 21. A pattern 73 of the photosensitive polyimide film remains in a portion other than on the scanning electrode 22 (FIG. 4(b)). After heat-treating the photosensitive polyimide film 73, the second electrode 5 of the diode element 6 and the semiconductor region 4 are patterned using a second photomask. Then, a wiring electrode layer is formed, and the wiring electrode 9 and the first electrode 3 of the diode element 6 and the first electrode layer 33 between the wiring electrode 9 and the pixel electrode 21 are patterned using a third photomask. Figure (C)). In the second embodiment, by using photosensitive polyimide as the insulating film, steps such as resist coating, development, and removal are unnecessary, and the manufacturing process can be further simplified. FIGS. 5(a) to 5(fd) are cross-sectional views showing the manufacturing process of the third embodiment. As in the first and second embodiments, second electrode layers 51, 52. Semiconductor layer 4L 42. First electrode layer 31°3
2 and pixel electrode 21. After forming the scanning electrode 22 by patterning, an insulating film is deposited and patterned in the same manner as in the first embodiment or the second embodiment to form the pixel electrode 2.
1. An insulating film pattern 7 is formed on the outside of the upper slope of the scanning electrode 22.
1 remains (Figure 5(a)). Next, the first wiring electrode layer 91
(Fig. 5(b)). Subsequently, the electrode layer 91 is patterned using a second photomask, and the formed pattern 92 is used as a mask for the second electrode layer 51, 52.
The semiconductor layers 41, 42 and the insulating film 71 are patterned to form the second electrode 5 of the diode element 6, the semiconductor region 4, and the insulating film 7 (FIG. 5(C)). Next, a second wiring electrode layer is deposited and patterned using a third photomask, thereby forming the pixel electrode 21 and the first wiring electrode 9.
A second wiring electrode 93 is formed to electrically connect 2. Then, using this second wiring electrode 93 and the first wiring electrode 92 patterned using a second photomask as a mask, unnecessary portions of the first electrode layer 31 and 32 are removed, and the first electrode 3 and the first electrode layer of the diode element 6 are removed. A first electrode layer 33 interposed between the second wiring electrode 93 and the pixel electrode 21 is formed (FIG. 5(d)). In each of the above embodiments, the first electrode layer 33 exists between the wiring electrode 9 or 93 and the pixel electrode 21 because
When M is used for the wiring electrode, it does not have good adhesion to a transparent conductive layer such as ITO, so a Cr layer or the like which has good adhesion to the transparent conductive layer is interposed. The a electrode and the pixel electrode or the scan electrode may be brought into direct contact as in the prior art. In that case, the second electrode layer 51. Next to the semiconductor 41, the first electrode layer 31 is also removed. A polymer substrate may be used instead of the glass substrate for the transparent insulating substrate 1 in each of the above embodiments, and the transparent electrode 21.
In addition to ITO, SnO or a metal thin film can be used for 22. The first electrode 3 and the second electrode 5 are used to block light from entering the semiconductor layer 4 and to prevent deterioration of device characteristics due to mutual diffusion between the transparent electrodes 21, 22 or the wiring electrodes 9, 92 and the semiconductor layer 4. In addition to Cr, T
The semiconductor layer 4 is made of amorphous or polycrystalline silicon, and the insulating film is made of the above-mentioned Si3N4 or photosensitive polyimide.
The wiring electrodes 9, 92゜93 are made of an inorganic material such as NG or an organic material, and in addition to the beams, a Cr layer Ti+N
Metal materials such as i and Mo are used. As a method for forming each layer, a vacuum evaporation method, a sputtering method, a plasma CVD method, a spin coating method, or the like can be applied.

【Effect of the invention】

According to the present invention, the insulating film covering the side surface of an active matrix type nonlinear element is patterned using the first electrode layer of the element on the transparent insulating substrate side, which is patterned using the same photomask as the pixel electrode or the scanning electrode, as a mask. By exposing light through the substrate, there is no need for a photomask for patterning the insulating film.
Only 3 types of photomasks are required compared to 4 types in the past.
The manufacturing process is simplified, and an active matrix element having a nonlinear element with uniform and small capacitance can be obtained.

[Brief explanation of drawings]

Figure 1 shows the manufacturing process of the first embodiment of the present invention.
2 is a plan view of the active matrix device manufactured according to the embodiment shown in FIG. 1, and FIGS. , are sectional views sequentially showing the manufacturing steps of the third and fourth embodiments. 1 Ni glass substrate, 20: ITO layer, 21: pixel electrode, 2
2: Scanning electrode, 3, 30.3L 32.33. 5
, 50.51°52: Cr layer, 4.40.41.4
2: Amorphous silicon layer, 6; Diode element, 7
．． 70.717 insulating film, 72.73: photosensitive polyimide film, 9: wiring electrode, 91: first wiring electrode, 92: second wiring electrode, 10, 12 resist.

Claims (1)

[Claims] 1) A semiconductor layer comprising a first electrode on the substrate side and a second electrode on the opposite side between a pixel electrode on a transparent insulating substrate and one scanning electrode, and the side surface is covered with an insulating film. When manufacturing a device to which nonlinear elements are connected, a transparent conductive layer, a first electrode layer, a semiconductor layer, and a second electrode layer are laminated on a transparent insulating substrate, and then
A step of sequentially patterning a second electrode layer, a semiconductor layer, a first electrode layer, and a transparent conductive layer in the same pattern as a pixel electrode and a scanning electrode using a first photomask, and depositing an insulating film, and depositing an insulating film on the insulating film. a step of patterning by photoetching by exposure through the substrate, and a step of forming at least a second electrode of the nonlinear element and a semiconductor layer on the pixel electrode and the scanning electrode, respectively, by sequential patterning using a second photomask. and a step of depositing a wiring electrode layer and patterning it using a third photomask to form wiring electrodes that connect the nonlinear element to the scanning electrode and the pixel electrode, respectively. A method for manufacturing a matrix element. 2) A method of manufacturing an active matrix element according to claim 1, characterized in that a photosensitive resist is deposited on the insulating film and the insulating film is photo-etched. 3) A method for manufacturing an active matrix element according to claim 1, wherein the insulating film is made of a photosensitive material.