JPH06151853A - Method for titanium pattern formation and manufacture of liquid crystal display - Google Patents

Abstract

PURPOSE:To prevent short circuits of gate electrodes composed of Ti and wiring, and prevent such electrodes and wiring from being stripped with respect to a liquid crystal display containing TFTs including such gate electrodes. CONSTITUTION:The title method includes a process wherein a titanium film is deposited on a glass substrate 1 by sputtering using an inert gas with nitrogen added at least in the early stage of film formation ; and process wherein a gate electrode 4 and other electrodes and wiring are formed on a thin film transistor by sputtering the resultant titanium film. The title method of manufacture consists of a process wherein an insulating film 6 is formed to cover at least the gate electrode 4 and the periphery thereof; process wherein an operating semiconductor layer 7 is deposited on the insulating film 6 on the gate electrode 4 and the periphery thereof; and process wherein a source 14 and drain 15 electrodes are formed on the gate electrode 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a titanium pattern and a method for manufacturing a liquid crystal display device, and more specifically, a method for 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.

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 for a gate electrode and a gate bus line.

In this case, it is required that the display screen has no defects, and there is a strong demand for a structure and a simple process in which the defects hardly occur.

[0004]

2. Description of the Related Art In a liquid crystal display panel of an active matrix driving system, thin film transistors (TFTs) are arranged in a matrix corresponding to individual pixels for dot display so that each pixel has a memory function and contrast. It is possible to display multiple 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 arranged in the X and Y directions, respectively, and a driving voltage is sequentially applied to each of these bus lines, so that By selectively driving a thin film transistor arranged corresponding to a bus line intersection, a voltage is applied to a desired pixel to display a dot.

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

An a-Si layer 54 is formed on the insulating film 53 that covers the gate electrode 52 and its periphery. Further, the a-Si layer 54 immediately above the gate electrode 53 is covered with the channel protective insulating film 55, and the a-Si operating semiconductor layer 54 on both sides of the a-Si layer 54 is covered with the 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 with the gate bus line GB integrally formed with the gate electrode 52.

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

[0010]

However, when forming the gate electrode 52 by this method, the gate electrode 52 is formed.
The Ti film, which is to be formed, floats up in the form of spots and has severe irregularities on its surface, so that the film easily peels off.

When SIMS analysis was performed to investigate the cause, as shown in FIG. 6, alteration products containing Ti and oxygen were generated on the surface of the glass substrate 51 that had been washed with an acid, and this caused a stain-like floating. Cause of.

Moreover, looking at the state after patterning the Ti film, the glass substrate 51 is caused by the residue of the alteration product containing Ti.
Since the thin low resistance layer 60 is formed on the surface of the glass substrate (FIG. 5A), the glass substrate 5 such as the gate electrode 52 and the gate bus line GB is formed.
There is an inconvenience that the wiring and electrodes formed on the surface of No. 1 easily leak.

The present invention has been made in view of the above problems, and prevents short-circuiting of electrodes and wirings made of Ti,
It is an object of the present invention to provide a method for forming a titanium pattern and a method for manufacturing a liquid crystal display device capable of preventing peeling of these electrodes and wirings.

[0014]

[Means for Solving the Problems]
3, a step of laminating the titanium film 2 on the glass substrate 1 by a sputtering method using an inert gas containing 20% or less of nitrogen at least at the initial stage of film formation, and the resist 3 And a step of patterning the titanium film 2 by using the mask as a mask.

Alternatively, at least at the initial stage of film formation, a step of laminating the titanium film 2 on the glass substrate 1 by a sputtering method using an inert gas containing 20% or less of nitrogen, and the titanium film 2 To form the gate electrode 4 of the thin film transistor, other electrodes and wirings by patterning, an insulating film 6 covering at least the gate electrode 4 and its periphery, and the gate electrode 4 and its periphery. An operating semiconductor layer 7 is formed on the insulating film 6.
And a step of forming the source electrode 14 and the drain electrode 15 on the gate electrode 4, and a method of manufacturing a liquid crystal display device.

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

[0017]

[Operation] According to the present invention, the Ti film 2 is formed on the glass substrate 1.
At the time of forming, the surface layer of the glass substrate 1 is made to contain nitrogen by slightly adding nitrogen as an inert gas.

According to this, the surface of the glass substrate 1 is guaranteed by nitrogen and is stable, and the Ti film 2 does not float up from the glass substrate 1 in a spot-like shape to form irregularities. Further, since the resistance of the surface of the glass substrate 1 is suppressed, the Ti film 2
No leakage will occur in the electrodes and wirings obtained by patterning.

[0019]

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

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, and FIG.
FIG. First, as shown in Fig. 2 (a),
A Ti film 2 is formed on the glass substrate 1 that has been surface-treated (acid cleaning, film formation, etc.) by the DC magnetron sputtering method.
The 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, spot-like unevenness does not occur on the surface. It was Moreover, when the Ti film 2 is patterned to form electrodes and wirings, almost no leak current occurs.

Therefore, if the content of nitrogen gas is 5%, 10%
When a Ti film 2 is formed as
The profile and layer structure shown in Fig. 1 (a) and (b) were obtained.
That is, a 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, in 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 is understood that the surface of the glass substrate 1 is in a state where it is likely to be altered by taking in a specific element in the atmosphere. Then, it was found that, when nitrogen was taken in the surface, the Ti film 2 laminated on the glass substrate 1 did not have spot-like lifting, no unevenness was generated on the surface, and the film adhesion was good. . Moreover, it was also revealed that the surface of the glass substrate 1 did not have low resistance.

According to the test results, the content of nitrogen gas in this case is preferably 5 to 20%. The nitrogen gas partial pressure is 2 × 10 ⁻⁴ to 8 × 10 ⁻⁴ Torr. After depositing the Ti film 2 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 the gate electrode 4 and the gate bus line 5 made of the Ti film 2 (FIG. 2 (b),
Figure 4 (a)).

After this, the photoresist 3 is peeled off and washed, and then a SiN film 6 serving as a gate insulating film is formed to a thickness of 400 nm by a plasma CVD method, and subsequently, a non-doped a- film is formed as an operating semiconductor layer. A Si layer 7 is laminated to a thickness of about 15 nm, and a stopper layer of 120 nm in thickness is further formed.
The SiN film 8 is continuously grown (FIG. 2 (d)).

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)). Then, using this as a mask, the upper SiN is formed by buffered hydrofluoric acid. After patterning the film 8, the photoresist 9 is peeled off (FIG. 2 (e)). This pattern of the SiN film 8 is used as a channel protective film 10 that covers 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 plasma CVD,
Then, the Ti film 12 is laminated by the sputtering method. After that, a photoresist 13 is applied and exposed and developed to form a pattern covering the drain region and the source region of the TFT separated on the channel protection film 10 and the drain bus line region connected to the drain region ( Figure 3
(a)).

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

After this, a photoresist 17 is applied,
This is exposed and developed to form a window 18 in the pixel area (FIG. 3 (c)). Then, after the ITO film 19 is formed by the sputtering method and 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. 3D and 4B). .

After that, the terminals are exposed to complete contact with the gate electrode 4 and the drain electrode 15 to complete the thin film transistor t. In such a TFT, nitrogen is contained in the surface of the glass substrate 1 and a low resistance layer due to the alteration is not generated, so that leakage of the gate electrode 4 and the gate bus line 15 and leakage of other wiring may occur. However, deterioration of the characteristics is suppressed.

[0032]

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

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view (1) showing a manufacturing process of a device according to an embodiment of the present invention.

FIG. 3 is a sectional view (2) showing the manufacturing process of the device according to the embodiment of the present invention.

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

5A and 5B are 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 chart showing the results of conventional SIMS analysis.

[Explanation of symbols]

1 Glass Substrate 2 Ti Film 3 Photoresist 4 Gate Electrode 5 Gate Busline 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 (72) Inventor Hiroyuki Yaegashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (3)

[Claims] 1. Nitrogen at 20% at least at the beginning of film formation.
Using the inert gas added below, a step of laminating the titanium film (2) on the glass substrate (1) by a sputtering method, and patterning the titanium film (2) using the resist (3) as a mask A method for forming a titanium pattern, comprising the steps of: 2. Nitrogen at 20% at least at the beginning of film formation.
A step of laminating a titanium film (2) on a glass substrate (1) by a sputtering method using an inert gas added below, and patterning the titanium film (2) to form a gate electrode ( 4), a step of forming other electrodes and wirings, a step of forming an insulating film (6) covering at least the gate electrode (4) and its periphery, and the insulation existing in the gate electrode (4) and its periphery A step of stacking an operating semiconductor layer (7) on the film (6), and a step of forming a source electrode (14) and a drain electrode (15) on the gate electrode (4). Method for manufacturing liquid crystal display device. 3. The method of manufacturing a liquid crystal display device according to claim 2, wherein the inert gas is argon.