JP3199873B2 - Method for forming titanium pattern and method for manufacturing liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a titanium pattern and a method of manufacturing a liquid crystal display device, and more particularly, to a method of forming a titanium pattern used for a gate electrode and the like, and a gate electrode made of titanium. The present invention relates to a method for manufacturing a liquid crystal display device having a thin film transistor using the same.

[0002] In a thin film transistor matrix structure used for driving an active matrix type display panel such as a liquid crystal display panel, titanium (Ti) is used as a material of a gate electrode and a gate bus line.

[0003] In this case, there is a demand for a display screen free from defects, and there is a strong demand for a structure and a simple process in which defects are unlikely to occur.

[0004]

2. Description of the Related Art A liquid crystal display panel of an active matrix drive system has a memory function in each pixel by arranging thin film transistors (TFTs) in a matrix corresponding to individual pixels for performing dot display. It is possible to display many lines well.

In such a liquid crystal display panel, for example, a large number of auxiliary capacitance bus lines, gate bus lines, and drain bus lines are respectively arranged in the X and Y directions, and a drive voltage is sequentially applied to each of these bus lines. By selectively driving the thin film transistors arranged corresponding to the bus line intersections, a voltage is applied to a desired pixel to perform dot display.

The structure of the thin film transistor is, for example, as shown in FIG. In FIG. 5, a gate electrode 52 of a TFT is formed on a glass substrate 51, and an insulating film 53 is laminated at least on and around the gate electrode 52.

An a-Si layer 54 is formed on the gate electrode 52 and the insulating film 53 covering the periphery thereof. Further, the a-Si layer 54 immediately above the gate electrode 53 is covered with a channel protective insulating film 55, and the a-Si operating semiconductor layers 54 on both sides of the a-Si layer 54 are interposed via an n ⁺ -type a-Si contact layer 56. A drain electrode 57 and a source electrode 58 are formed, and a transparent pixel electrode 59 is connected to the source electrode 58.

The insulating film 53 on the gate electrode 52 becomes a gate insulating film. Further, the drain bus line DB connected to the drain electrode 57 is arranged in a direction intersecting the gate bus line GB formed integrally with the gate electrode 52.

As a procedure for forming the gate electrode 52 with Ti, first, after cleaning the glass substrate 51 with an acid, a Ti film (not shown) is deposited by a sputtering method, and then the Ti film is deposited by a photolithography method. The film is patterned to form a gate electrode 52 and a gate bus line GB.
Is formed.

[0010]

However, when the gate electrode 52 is formed by this method, the gate electrode 52
The resulting Ti film floats up in a stain-like manner, causing severe irregularities on its surface, so that the film is easily peeled off.

As a result of SIMS analysis for investigating the cause, as shown in FIG. 6, altered substances containing Ti and oxygen are generated on the surface of the glass substrate 51 washed with acid, and these are stain-like floating. Cause.

Moreover, looking at the state after patterning the Ti film, the residue of the altered substance containing Ti shows that the glass substrate 51
(FIG. 5A), a thin low-resistance layer 60 is formed on the surface of the glass substrate 5 such as the gate electrode 52 and the gate bus line GB.
There is an inconvenience that the wirings and electrodes formed on the surface of the first electrode tend to leak.

The present invention has been made in view of such a problem, and prevents a short circuit of an electrode or a wiring made of Ti.
An object of the present invention is to provide a method for forming a titanium pattern and a method for manufacturing a liquid crystal display device, which can prevent the separation of these electrodes and wirings.

[0014]

Means for Solving the Problems The above-mentioned problems are solved in FIGS.
3, a step of laminating the titanium film 2 on the glass substrate 1 by a sputtering method using an inert gas added with nitrogen at 20% or less at least at the beginning of the film formation; And a step of patterning the titanium film 2 using the mask as a mask.

Alternatively, a step of laminating a titanium film 2 on a glass substrate 1 by a sputtering method using an inert gas to which nitrogen is added at 20% or less at least at the initial stage of film formation; Forming a gate electrode 4 of the thin film transistor, other electrodes and wiring, forming an insulating film 6 covering at least the gate electrode 4 and the periphery thereof, and forming a pattern on the gate electrode 4 and the periphery thereof. An operating semiconductor layer 7 on a certain insulating film 6
And a step of forming a source electrode 14 and a drain electrode 15 on the gate electrode 4.

Alternatively, the method is achieved by a method for manufacturing a liquid crystal display device, wherein the inert gas is argon.

[0017]

According to the present invention, a Ti film 2 is formed on a glass substrate 1.
Is formed, a slight amount of nitrogen is contained as an inert gas so that nitrogen is contained in the surface layer of the glass substrate 1.

According to this, the surface of the glass substrate 1 is secured by nitrogen and becomes stable, and the Ti film 2 does not float up from the glass substrate 1 in a stain-like manner, and no irregularities are generated. Further, since the lowering of the resistance of the surface of the glass substrate 1 is suppressed, the Ti film 2
No leakage occurs in the electrodes and wirings obtained by patterning the electrodes.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an atomic concentration distribution diagram showing an example of SIMS analysis results of a Ti film formed according to the present invention and a glass substrate thereunder.

FIGS. 2 and 3 are sectional views showing steps of forming a TFT and a pixel electrode of the temporary liquid crystal display device of the present invention.
Is a plan view of the same. First, as shown in FIG.
On a glass substrate 1 that has been subjected to a surface treatment (acid cleaning, film formation, etc.), a Ti film 2
Film is formed to a thickness of nm. According to the sputtering method, for example, argon is used as an inert gas for knocking out an element from a Ti target, but when a slight amount of nitrogen gas is added to the argon gas, stain-like irregularities do not occur on the surface. Was. Moreover, when the Ti film 2 is patterned to form electrodes and wirings, almost no leak current is generated.

Therefore, the content of nitrogen gas is reduced to 5%, 10%
As a result of the SIMS analysis, a Ti film 2 is formed as
A profile and a layer structure as shown in FIGS. 1 (a) and 1 (b) were obtained.
That is, an SiO ₂ layer and a layer containing more nitrogen than oxygen are continuously formed on the surface of the glass substrate 1, and these altered layers contain a small amount of Ti. In addition, the part near the altered layer
The Ti layer contains nitrogen.

In this case, the nitrogen gas is introduced into the sputtering apparatus along with the argon gas throughout the growth of the Ti film, but the glass substrate 1 takes in more nitrogen than the Ti film 2 and A thin TiN layer is formed near the interface.

From this, it can be seen that the surface of the glass substrate 1 is in a state in which a specific element in the atmosphere is taken in and the surface is easily deteriorated. Then, when nitrogen was taken into the surface, it was found that the Ti film 2 laminated on the glass substrate 1 had no stain-like lifting, no irregularities were generated on the surface, and the film had good adhesion. . Moreover, it has also been found that the surface of the glass substrate 1 has not been reduced in resistance.

According to the test results, the content of nitrogen gas in this case is preferably 5 to 20%. Note that the partial pressure of nitrogen gas is 2 × 10 ⁻⁴ to 8 × 10 ⁻⁴ Torr. After the Ti film 2 is deposited by the above method, the photoresist 3
Is applied, exposed and developed to form a pattern covering the gate region and the gate bus line region of the transistor (FIG. 2).
(b)).

Next, the Ti film 2 is etched using the photoresist 3 as a mask, thereby forming a gate electrode 4 and a gate bus line 5 made of the Ti film 2 (FIG. 2B,
FIG. 4 (a)).

Thereafter, the photoresist 3 is peeled off, and after cleaning, an SiN film 6 serving as a gate insulating film is formed to a thickness of 400 nm by a plasma CVD method. A Si layer 7 is laminated to a thickness of about 15 nm, and a stopper layer having a thickness of 120 nm is formed.
The SiN film 8 is continuously grown (FIG. 2D).

In this case, the SiN films 6 and 8 are grown in a mixed gas atmosphere of SiH ₄ and NH ₂ , and the a-Si layer 7 is formed in a SiH ₄ gas atmosphere. Next, a photoresist 9 is applied, and this is exposed and developed to form a pattern along the gate electrode 4 (FIG. 2 (d)). After patterning the film 8, the photoresist 9 is stripped (FIG. 2 (e)). The pattern of the SiN film 8 is used as a channel protective film 10 covering the a-Si film 7 on the gate electrode 4.

Thereafter, an n ⁺ -type a-Si layer 11 for contact is grown to a thickness of 50 nm by a plasma CVD method.
Subsequently, a Ti film 12 is stacked by a sputtering method. Thereafter, a photoresist 13 is coated, exposed and developed to form a pattern covering the drain region and the source region of the TFT separated on the channel protective film 10 and the drain bus line region connected to the drain region ( FIG.
(a)).

Next, using the photoresist 13 as a mask, the uppermost Ti film 12 and the n ⁺ -type a-Si layer 11 are etched by RIE (Reactive Ion Etching). A source electrode 14 and a drain electrode 15 are formed on both sides, and a drain bus line 16 is formed. Subsequently, after the a-Si layer 7 is etched to separate elements, the photoresist 13 is peeled off (FIGS. 3B and 4B).

Thereafter, a photoresist 17 is applied,
This is exposed and developed to form a window 18 in the pixel area (FIG. 3C). Then, after forming the ITO film 19 by the sputtering method, when the photoresist 17 is peeled off, the ITO film 19 remains only in the pixel region and is used as the pixel electrode 20 (FIGS. 3 (d) and 4 (b)). .

Thereafter, terminals are provided to make contact with the gate electrode 4 and the drain electrode 15 to complete the thin film transistor t. In such a TFT, since the surface of the glass substrate 1 contains nitrogen and a low-resistance layer is not generated due to the deterioration, leakage of the gate electrode 4 and the gate bus line 15 and leakage of other wiring may occur. And deterioration of characteristics is suppressed.

[0032]

As described above, according to the present invention, when a Ti film is formed on a glass substrate by sputtering,
Since a slight amount of nitrogen is contained as an inert gas and nitrogen is contained in the surface layer of the glass substrate, the surface of the glass substrate becomes stable, the adhesion between the Ti film and the glass substrate is improved, and a highly reliable device is provided. Can be formed. Further, since the lowering of the resistance of the surface of the glass substrate is suppressed, it is possible to prevent leakage of electrodes and wirings obtained by patterning the Ti film.

[Brief description of the drawings]

FIG. 1 is an atomic concentration distribution diagram showing a SIMS analysis result of one example of the present invention.

FIG. 2 is a cross-sectional view (part 1) illustrating a manufacturing process of the apparatus according to the embodiment of the present invention;

FIG. 3 is a sectional view (No. 2) showing a manufacturing step of the apparatus according to the embodiment of the present invention;

FIG. 4 is a plan view showing a manufacturing process of the device according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view and a plan view showing a TFT and a pixel electrode formed by a conventional method.

FIG. 6 is an atomic concentration distribution diagram showing a conventional SIMS analysis result.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Ti film 3 Photoresist 4 Gate electrode 5 Gate bus line 6 SiN film 7 a-Si layer 8 SiN film 9, 13 Photoresist 10 Channel protective film 11 n ⁺ type a-Si layer 12 Ti film 14 Source electrode 15 Drain electrode 16 Drain bus line

Continuation of the front page (51) Int.Cl. ⁷ Identification code FIG02F 1/136 500 (72) Inventor Hiroyuki Yaegashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (58) Investigated field (Int. (Cl. ⁷ , DB name) H01L 29/786 H01L 21/285 301 H01L 21/3205 C23C 14/06 G02F 1/1343 G02F 1/1368

Claims (3)

(57) [Claims] 1. At least at the beginning of film formation, nitrogen is added to 20
% Of a titanium film formed on a glass substrate by a sputtering method using an inert gas added at a concentration of not more than 10%, and a step of patterning the titanium film using a resist as a mask. The method of forming the pattern. 2. Nitrogen is added at least at the beginning of the film formation.
%, A step of laminating a titanium film on a glass substrate by a sputtering method using an inert gas added at a concentration of not more than 10%, and forming a gate electrode of a thin film transistor, other electrodes and wiring by patterning the titanium film. A step of forming an insulating film covering at least the gate electrode and its periphery; a step of laminating an operating semiconductor layer on the insulating film at the gate electrode and its periphery; and a source above the gate electrode. Forming an electrode and a drain electrode. 3. The method for manufacturing a liquid crystal display device according to claim 2, wherein said inert gas is argon.