JPH09293877A - Wiring structure and formation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable east and perfect removal of an anodic oxidation mask formed in the surface of a connection pad connected to a gate electrode via a gate line, after an anodic oxidation film is formed on the surface of the gate electrode for formation of a thin-film transistor in an active matrix type liquid crystal display unit. SOLUTION: Only the surface of a connection pad 14 is covered with an anodic oxidation mask 17 made of silicon oxide, under which condition to pad is anodized to form an anodic oxidation film 18 on the surface of a gate electrode 12. Next, a gate insulating film 19 made of silicon nitride is formed all over the film 18. Thereafter, a contact hole 25 is made in the gate insulating film 19 and anodic oxidation mask 17 at their parts corresponding to a central part of the connection pad 19. In this case, the film 19 and mask 17 can be easily etched collectively. In addition, the mask 17 can be perfectly removed from on the top face of the pad 14 in the contact hole 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure and a method for forming the structure.

[0002]

2. Description of the Related Art For example, in an active matrix type liquid crystal display device, a gate electrode of a thin film transistor as a switching element is formed of Al-Ti (Al alloy containing Ti), and anodization is performed to form a gate electrode. There is a structure in which an anodic oxide film made of Al-Ti-Ox is formed on the surface of and the anodic oxide film is made to function as a part of the gate insulating film to supplement the original breakdown voltage of the gate insulating film. .

Next, an example of a method of forming a gate wiring composed of a gate electrode and the like in such a conventional liquid crystal display device will be described with reference to FIGS. 11 to 14 in order. First, as shown in FIGS. 11A and 11B, a gate wiring made of Al—Ti (a gate line including a gate electrode and a gate made of a connection pad connected to the gate line is formed on the entire upper surface of the glass substrate 1. A wiring) forming film 2 is formed. Next, the first photoresist mask 3 is formed at a predetermined position on the upper surface of the gate wiring forming film 2. Next, if dry etching or wet etching is performed,
As shown in FIGS. 12A and 12B, a gate line 5 including a gate electrode 4 and a connection pad 6 connected to a predetermined one end of the gate line 5 are formed under the first photoresist mask 3. It After that, the first photoresist mask 3 is removed. Next, as shown in FIGS. 13A and 13B, a second photoresist mask 7 is formed so as to cover only the surface of the connection pad 6. Next, when anodic oxidation is performed, as shown in FIGS. 14A and 14B, the gate line 5 not covered with the second photoresist mask 7 is formed.
An anodic oxide film 8 made of Al-Ti-Ox is formed on the surface of the gate electrode 4 and the surface of the gate electrode 4. After that, when the second photoresist mask 7 is removed, the surface of the connection pad 6 is exposed. In this case, the reason why the anodic oxide film is not formed on the surface of the connection pad 6 is that the anodic oxide film has an insulating property.
This is to prevent the connection function of the connection pad 6 from being hindered.

[0004]

By the way, the second photoresist mask 7 for anodization is baked at the time of forming the first photoresist mask 3 for etching so as not to be peeled off during anodization. Compared with, it is formed by baking at high temperature for a long time. Therefore, the peelability of the second photoresist mask 7 for anodic oxidation is deteriorated, and when the second photoresist mask 7 is removed, it may partially remain on the surface of the connection pad 6. Then, the second photoresist mask 7 that partially remains
Cannot be removed by etching, which will be described later, when forming a contact hole. In such a case, although not shown, the conductivity between the connection electrode formed on or connected to the surface of the connection pad 6 and the connection pad 6 may deteriorate, and the thin film transistor may not operate. There was a problem. An object of the present invention is to make it possible to easily and completely remove the anodizing mask formed on the surface of the connection pad.

[0005]

According to a first aspect of the present invention, there is provided a wiring structure in which a peripheral portion of the connection pad on the surface of the wiring having the connection pad is covered with an inorganic film, and at least the center of the connection pad is formed. An anodic oxide film is formed on the surface of the wiring except the part. According to a fourth aspect of the present invention, in the method for forming a wiring, the inorganic film covers at least a part of the connection pad on the surface of the wiring having the connection pad, and anodization is performed in this state to form the inorganic film An anodic oxide film is formed on the surface of the wiring which is not covered by.

According to the present invention, since the inorganic film such as silicon oxide or silicon nitride is used as the mask for anodic oxidation instead of the organic film such as photoresist, the anodic oxidation formed on the surface of the connection pad. The inorganic film as a mask for use can be easily and completely removed.

[0007]

1 to 7 show respective manufacturing steps of a liquid crystal display device to which the first embodiment of the present invention is applied. Therefore, the structure of the wiring and the method for forming the wiring in this embodiment will be described with reference to these drawings in order.

First, as shown in FIGS. 1 (A) and 1 (B),
A gate line made of Al—Ti, that is, a gate line 13 including a gate electrode 12 and a connection pad 14 connected to a predetermined one end of the gate line 13 are formed at a predetermined position on the upper surface of the glass substrate 11. Next, a silicon oxide film (inorganic film) 15 for forming an anodizing mask is formed on the entire upper surface by sputtering. Next, the first photoresist mask 16 is formed at a predetermined position on the upper surface of the silicon oxide film 15. Next, when dry etching or wet etching is performed, as shown in FIGS.
An anodic oxidation mask 17 is formed under the first photoresist mask 16 as shown in FIG. That is, the anodic oxidation mask 17 is formed so as to cover only the surface of the connection pad 14. Then, the first photoresist mask 16 is removed. Next, when anodic oxidation is performed, as shown in FIGS. 3A and 3B, Al-Ti-Ox is formed on the surface of the gate line 13 and the surface of the gate electrode 12 which are not covered by the anodic oxidation mask 17. An anodic oxide film 18 of is formed.

Next, as shown in FIGS. 4 (A) and 4 (B),
A gate insulating film 19 made of silicon nitride is formed on the entire upper surface, and then a semiconductor thin film 20 made of amorphous silicon or the like is formed on the entire upper surface. Next, a channel protection film 21 made of silicon nitride is formed on a predetermined portion of the upper surface of the semiconductor thin film 20 in a portion corresponding to the gate electrode 12. Next, the n ⁺ silicon layer 22 is formed on the entire upper surface. Next, n on both sides of the upper surface of the channel protective film 21
^{+ A} second photoresist mask 23 is formed at two predetermined places on the upper surface of the silicon layer 22. Next, when dry etching or wet etching is performed, as shown in FIG.
As shown in (B), an n ⁺ silicon layer 22a for a source and an n ⁺ silicon layer 22b for a drain are formed under each of the two second photoresist masks 23, and under the two second photoresist masks 23. Also, the semiconductor thin film 20 remains under the channel protective film 21. Then, the second photoresist mask 23 is removed.

Next, as shown in FIGS. 6 (A) and 6 (B),
A pixel electrode 24 made of ITO is formed at a predetermined position on the upper surface of the gate insulating film 19. Next, a contact hole 25 is formed in the gate insulating film 19 and the anodic oxidation mask 17 in the portion corresponding to the central portion of the connection pad 14 to expose the upper surface of the central portion of the connection pad 14. In this case, the gate insulating film 19 made of silicon nitride and the anodizing mask 17 made of silicon oxide can be easily etched together with the same dry etching gas or the same wet etching solution. Therefore, the upper surface of the connection pad 14 in the contact hole 25 can be etched without leaving the anodic oxidation mask 17 at all. By the way, in this state, the peripheral portion of the connection pad 14 is covered with the anodizing mask 17 and the gate insulating film 19. The exposed upper surface of the central portion of the connection pad 14 has conductivity because the anodic oxide film 18 is not formed.

Next, as shown in FIGS. 7A and 7B,
A source contact layer 26a, a drain contact layer 26b, and a connection pad contact made of Cr are formed on the upper surface of the source n ⁺ silicon layer 22a, the upper surface of the drain n ⁺ silicon layer 22b, and the upper surface of the connection pad 14 in the contact hole 25. The layer 27 is formed, and the source contact layer 26a and the drain contact layer 26 are formed.
A source electrode 28a, a drain electrode 28b, and a connection electrode 29 made of Al are formed on each upper surface of the contact layer 27b and the contact pad contact layer 27. In this case, the drain line 30 including the Cr layer and the Al layer is simultaneously formed at a predetermined position on the upper surface of the gate insulating film 19. The source contact layer 26a and the source electrode 28a are formed so as to be connected to the pixel electrode 24. Thus, a part of the liquid crystal display device in this embodiment is manufactured.

As described above, in this embodiment, since it is possible to completely prevent the anodic oxidation mask 17 made of silicon oxide from remaining on the upper surface of the connection pad 14 in the contact hole 25, the mask 17 is formed thereon. The conductivity between the connection pad contact layer 27 and the connection electrode 29 and the connection pad 14 can be improved, and thus the thin film transistor can be operated normally. In addition, a contact hole 25 is formed in the gate insulating film 19.
Since the unnecessary anodic oxidation mask 17 on the connection pad 14 can be removed at the same time when forming, the number of steps can be prevented from increasing.

Next, regarding the second embodiment of the present invention,
This will be described with reference to FIGS. 8 to 10 in order. First, FIG.
As shown in (A) and (B), a plurality of connection pads 14 linearly arranged at predetermined locations on the upper surface of the glass substrate 11.
A mask 17 for anodic oxidation is formed so as to cover all of the above.
Next, when anodic oxidation is performed, as shown in FIG. 9A, an anodic oxide film 18 is formed on the surface of the gate line 13 not covered by the anodic oxidation mask 17 and the surface of the gate electrode (not shown). . Next, as shown in FIGS. 9A and 9B, after forming the gate insulating film 19, the gate insulating film 19 in a portion corresponding to the central portion of the connection pad 14 is formed.
Then, a contact hole 25 is formed in the anodizing mask 17. Also in this case, the gate insulating film 19 and the anodic oxidation mask 17 can be easily etched together. Further, it is possible to perform etching so that the mask 17 for anodization does not remain on the upper surface of the connection pad 14 in the contact hole 25. Next, FIG.
As shown in (B), the contact pad contact layer 27 is formed on the upper surface of the contact pad 14 in the contact hole 25.
And the connection electrode 29 is formed.

By the way, in the second embodiment, as shown in FIG.
As shown in (A) and (B), since the mask 17 for anodization is formed so as to cover all the plurality of connection pads 14 arranged in a straight line, the positional accuracy of the mask 17 for anodization is high. Can be somewhat rough. Therefore, the anodic oxidation mask 17 in this case may be formed by sputtering using a hard mask. Further, in any of the embodiments, the anodizing mask 17 may be formed by printing such as letterpress printing or screen printing. In the case of printing,
After printing on the entire surface, the anodizing mask 17 may be formed by photolithography. further,
The anodic oxidation mask 17 may be made of the same material as the gate insulating film 19 (for example, silicon nitride).

[0015]

As described above, according to the present invention, since the inorganic film such as silicon oxide or silicon nitride is used as the mask for anodic oxidation, not the organic film such as photoresist, the connection pad is used. It is possible to easily and completely remove the inorganic film as the anodizing mask formed on the surface of the connection pad, and therefore the conductivity between the connection electrode formed on or connected to the surface of the connection pad and the connection pad is improved. Can be

[Brief description of drawings]

FIG. 1 shows an initial step in manufacturing a liquid crystal display device to which a first embodiment of the present invention is applied,
(A) is a plan view and (B) is a sectional view taken along the line BB.

2A and 2B show a step following FIG. 1, in which FIG. 2A is a plan view and FIG. 2B is a sectional view taken along the line BB.

3A and 3B show a step following FIG. 2, in which FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along the line BB.

4A and 4B are views showing a step following FIG. 3, in which FIG. 4A is a plan view and FIG. 4B is a sectional view taken along line BB thereof.

5A and 5B show a step following FIG. 4, in which FIG. 5A is a plan view and FIG. 5B is a cross-sectional view taken along line BB thereof.

6A and 6B are diagrams showing a step following FIG. 5, in which FIG. 6A is a plan view and FIG. 6B is a cross-sectional view taken along line BB thereof.

7A and 7B are views showing a step following FIG. 6, in which FIG. 7A is a plan view and FIG. 7B is a sectional view taken along line BB thereof.

FIG. 8 shows an initial step in manufacturing a liquid crystal display device to which the second embodiment of the present invention is applied,
(A) is a plan view and (B) is a sectional view taken along the line BB.

9A and 9B are diagrams showing a step following FIG. 8, in which FIG. 9A is a plan view and FIG. 9B is a cross-sectional view taken along line BB thereof.

FIG. 10 shows a step that follows FIG.
Is a plan view, and (B) is a cross-sectional view along the line BB.

11A and 11B show an initial step in manufacturing a conventional liquid crystal display device, in which FIG. 11A is a plan view and FIG. 11B is a cross-sectional view taken along the line BB.

FIG. 12 shows a step that follows FIG.
(A) is a plan view and (B) is a sectional view taken along the line BB.

FIG. 13 shows a step that follows FIG. 12,
(A) is a plan view and (B) is a sectional view taken along the line BB.

FIG. 14 shows a step that follows FIG.
(A) is a plan view and (B) is a sectional view taken along the line BB.

[Explanation of symbols]

 12 gate electrode 13 gate line 14 connection pad 17 anodizing mask (inorganic film) 18 anodizing film

Claims (6)

[Claims] 1. A surface of a wiring having a connection pad, a peripheral portion of the connection pad being covered with an inorganic film, and an anodic oxide film being formed on a surface of the wiring except at least a central portion of the connection pad. Wiring structure characterized by. 2. A peripheral portion of the connection pad is covered with an inorganic film on a surface of a gate wiring including a gate line including a gate electrode for forming a part of a thin film transistor and a connection pad connected to the gate line. A wiring structure in which an anodic oxide film is formed on the surface of the gate wiring except at least the central portion of the connection pad. 3. The method according to claim 1, wherein
The wiring structure, wherein the inorganic film is made of silicon oxide or silicon nitride. 4. An inorganic film covers at least a part of the connection pad on the surface of the wiring having the connection pad,
A method of forming a wiring, characterized by forming an anodized film on the surface of the wiring not covered with the inorganic film by performing anodization in this state. 5. A surface of a gate wiring comprising a gate line including a gate electrode for forming a part of a thin film transistor and a connection pad connected to the gate line, at least a part of the connection pad being covered with an inorganic film. The method for forming a wiring is characterized by forming an anodized film on the surface of the gate wiring not covered with the inorganic film by performing anodization in this state. 6. The invention according to claim 4, wherein
The method for forming a wiring, wherein the inorganic film is made of silicon oxide or silicon nitride.