JPH0313921A - Production of thin-film diode - Google Patents

Abstract

PURPOSE:To protect the regions of a glass substrate where transparent conductive films are removed against the corrosion due to etching by forming semiconductor layers to cover the regions of the glass substrate where the transparent conductive films between picture element electrodes and scanning electrodes are removed and removing the unnecessary parts in the semiconductor layers with wiring electrodes as a mask. CONSTITUTION:ITO is deposited on the glass substrate 1 and is subjected to a 1st patterning, by which the picture element electrodes 21, 22 and the scanning electrodes 23 are formed. Amorphous silicon is then deposited and is subjected to a 2nd patterning to form coat the regions 6A, 6B of the exposed parts of the glass substrate 1 formed by the 1st patterning with the semiconductor layers 3A, 3B. Mo is then deposited as the wiring electrodes and is etched by a 3rd patterning to form the wiring electrodes 4A; further, the unnecessary semiconductor layers 3A of the semiconductor layers formed in the previous stage are removed with the electrodes 4A as a mask to pattern the diode elements 5. The semiconductor layers are not corroded by the etching soln. in the 3rd patterning and, therefore, the glass regions 6A, 6B are protected against corrosion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a thin film diode, and more particularly to a method for manufacturing a thin film diode that is free from ionic impurities from a glass substrate and has excellent characteristics.

[Conventional technology]

Thin film display devices such as liquid crystal displays are used in large quantities as display devices for small electronic devices such as calculators and watches.
Currently, the goal is to make the screen larger and have higher image quality. An effective method for displaying high-quality images on a large screen is an active matrix method in which each pixel on the screen is provided with a switching element.

As switching elements used in the active matrix method, three-terminal elements such as thin film transistors (TPT), two-terminal nonlinear elements such as MIM (metal-insulator-metal) elements, varistors, and thin-film diodes have been proposed, and two-terminal nonlinear elements such as Since the nonlinear element has a simple structure, the manufacturing cost can be lower than that of an active matrix method using a three-terminal element.

The switching elements used in the active matrix method involve a process of depositing a thin film such as a metal film or a semiconductor film on a glass substrate, and etching the thin film through a chemical or physical reaction using a strongly acidic solution or corrosive gas. It is manufactured by repeating the patterning process (corrosion) processing.

FIG. 3 is a cross-sectional view showing the manufacturing process of a conventional thin film diode. As shown in FIG. 3 (al), rTO is deposited as a transparent conductive film on the glass substrate 1 and patterned in a first pattern to form pixel electrodes 21, 22 and scanning electrodes 23,
Next, deposit amorphous silicon and apply C in a second pattern.
Plasma etching is performed using a mixed gas of F4 and 08 to form a pattern of amorphous silicon 3. Next, Mo is deposited as the wiring 1tFIi as shown in FIG. Wiring electrode 4 is patterned by wet etching using a mixed solution of acetic acid. Further, as shown in FIG. 3+c+, a diode element 5 is patterned by plasma etching the amorphous silicon using a mixed gas of CFm and Ol and using the wiring electrode 4 as a mask.

[Problems to be Solved by the Invention] However, in such a conventional method for manufacturing a thin film diode, the region 6A of the glass substrate regions 6A and 6B from which the transparent conductive film has been patterned and removed in the first pattern is amorphous silicon 3. The glass surface is corroded due to exposure to corrosive gas during etching and strong acid etching solution during wiring electrode 4-processing, and ionic substances such as sodium and potassium inside the glass precipitate and diffuse on the glass surface. There has been a problem in that the performance of the diode element 5 and the liquid crystal material is degraded due to contamination with ionic substances, and the image quality and reliability of the display device are degraded. There is also a chance of corrosion in the glass substrate region 6B, although it is less than in the glass substrate region 6A.

The present invention has been made in view of the above-mentioned points, and its object is to provide a method for manufacturing a thin film diode with excellent characteristics by minimizing corrosion caused by etching in the region of the glass substrate from which the transparent conductive film has been removed. It is in.

[! Means for Solving Problem 1] According to the present invention, the above object is to form pixel electrodes and scanning electrodes on a glass substrate using a transparent conductive film, and then to laminate semiconductor layers and wiring electrodes in a predetermined pattern. In the method for manufacturing a thin film diode, (1) a glass substrate region 6 from which a transparent conductive film is removed at least between a pixel electrode and a scanning electrode;
A step of covering A and 6B to form semiconductor layers 3A and 3B, and (2) using the distributed TiA electrode 4A as a mask, removing unnecessary semiconductor layer 3A from among the semiconductor layers formed in the above step. This is achieved by comprising a process.

[Effect]

The semiconductor layers 3A, 3B are not removed by dry etching because they are masked by the second pattern, and therefore the glass substrate regions 6A, 6B are not corroded by the etching gas.The third pattern forms the wiring amount i4A. In this case, the semiconductor layer is not corroded by the etching solution and therefore the glass 1&
The Fi regions 6A and 6B do not come into contact with the etching solution, and the glass substrate region 6^ is exposed in the process of removing unnecessary semiconductor layers.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the manufacturing process of a thin film diode according to an embodiment of the present invention, FIG. FIG. 1 (C1 is a cross-sectional view showing a step of removing an unnecessary semiconductor layer. FIG. 2 is a plan view corresponding to FIG. 1 (5).

As shown in FIG. 1 (ta) and FIG. 2, ITO is deposited as a transparent conductive film on a glass substrate 1 and patterned in a first pattern to form pixel electrodes 21, 22 and scanning electrodes 23,
Next, deposit amorphous silicon and apply C in a second pattern.
Fa and 0! Amorphous silicon is patterned by plasma etching using a mixed gas of In this step, at least the glass substrate regions 6A and 6B from which the transparent conductive film has been removed in the first pattern are covered with a semiconductor layer, and openings 7A and 7B are formed in the portions where the wiring electrodes and the transparent electrodes are electrically connected. . 7B is ITO of other y/thin film diodes not shown in the active matrix.
As shown in Figure 1), Mo is deposited as a wiring electrode and phosphoric acid is applied in a third pattern.

Wiring electrodes 4A are patterned by etching Mo using a mixed solution of nitric acid and acetic acid. Furthermore, Figure 1 tc
As shown in +, CF4 and 0. Using the wiring electrode 4A as a mask, the amorphous silicon is plasma etched using a mixed gas to form the diode element 5 by patterning.

〔Effect of the invention〕

According to this invention, in a method for manufacturing a thin film diode, in which a pixel electrode and a scanning electrode are formed using a transparent conductive film on a glass substrate, and then a semiconductor layer and a wiring electrode in a predetermined pattern are laminated, +l) at least a pixel electrode and a scanning electrode are formed. (2) forming a semiconductor layer by covering the glass substrate region from which the transparent conductive film between the scanning electrodes has been removed; (2) using the wiring electrode as a mask to remove unnecessary parts of the semiconductor layer formed in the above step Since the glass substrate region from which the transparent conductive film has been removed is exposed to fewer etching steps, as a result, the incorporation of ionic substances into the semiconductor layer due to corrosion of the glass is eliminated. A thin film diode with excellent characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 shows the manufacturing process of a thin film diode according to an embodiment of the present invention, FIG. 1fa) is a cross-sectional view showing the process of forming a semiconductor layer, and FIG. 1('b) shows the process of forming a wiring electrode. Cross-sectional view, FIG. 1 (C1 is a cross-sectional view showing the process of removing unnecessary semiconductor layers, FIG. 2 is a plan view corresponding to
The figure shows the manufacturing process of a conventional thin film diode.
al is a sectional view showing the process of forming a semiconductor layer, FIG. 3) is a sectional view showing the process of forming a wiring electrode, and FIG. 3(C) is a sectional view showing the process of removing an unnecessary semiconductor layer. 1 glass substrate, 21, 22: pixel electrode, 23: scanning!
Pole, 3A, 3B: semiconductor layer, 4A: wiring electrode, 5: diode element, 6A, 6B: glass substrate region from which transparent conductive film has been removed, 7A, 7BF opening.

Claims (1)

[Claims] 1) A method for manufacturing a thin film diode in which a pixel electrode and a scanning electrode are formed using a transparent conductive film on a glass substrate, and then a semiconductor layer and a wiring electrode in a predetermined pattern are laminated. (2) forming a semiconductor layer by covering the region of the glass substrate from which the transparent conductive film between the pixel electrode and the scanning electrode has been removed; (2) using the wiring electrode as a mask, the semiconductor layer formed in the above step; A method for manufacturing a thin film diode, comprising the step of removing an unnecessary semiconductor layer of the thin film diode.