JPH06230421A - Method of manufacturing thin film transistor matrix - Google Patents

Abstract

(57) [Summary] [Objective] Regarding the manufacturing method of a thin film transistor (TFT) matrix, the object is to suppress the increase in the number of steps and increase the transmittance of the TFT matrix to achieve high brightness and high performance of the liquid crystal panel. And [Structure] Atomic layer deposition (ALD) method was used on the transparent insulating substrate 1 to form the transparent conductive film 11 made of ZnO: Al film and the auxiliary capacitor dielectric film made of Al ₂ O _{3 as} the auxiliary capacitor electrode. Body membrane
12 is formed, the gate electrode 2 is formed on the substrate, the gate insulating film 4, the operating semiconductor layer 5, and the channel protective film 6 are sequentially formed on the substrate, leaving the channel protective film directly above the gate electrode. After patterning, a contact layer 7 made of a high-concentration semiconductor and a metal film 8 are sequentially formed on the substrate, patterning is performed to form a drain electrode and a source electrode, a transparent electrode film is formed on the substrate, and a source is formed. The pixel electrode 10 is formed by patterning so as to be connected to the electrode, and an auxiliary capacitance is formed with the transparent conductive film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film transistor (TFT) matrix formed in a liquid crystal panel or the like by an active matrix driving method.

Development of a TFT matrix type liquid crystal panel for use in a laptop personal computer and a wall-mounted television is in progress. In recent years, TFT-matrix liquid crystal panels are required to have high brightness and high image quality, and the development of their manufacturing technology is in progress.

[0003]

2. Description of the Related Art A liquid crystal panel based on an active matrix driving system has TFTs arranged in a matrix corresponding to individual pixels for dot display, and each pixel has a memory function to enable multi-line display with good contrast. .

FIGS. 4A to 4C are explanatory views of the TFT matrix. Figure 4 (A) is a plan view and Figure 4 (B) is a cross-sectional view taken along the line AA and TF.
The T part, Fig. 4 (C), is a sectional view taken along the line BB, which shows the auxiliary capacitance (CS) part.

The TFT matrix type liquid crystal panel is connected to both bus line intersections by applying a drive voltage to a large number of gate bus lines 2 and drain bus lines 9 arranged in a matrix so as to intersect in the X and Y directions. By selectively driving the selected TFT, the corresponding desired pixel is displayed in dots. Such a TFT matrix structure has a structure in which a large number of gate bus lines and drain bus lines are formed on a transparent insulating glass substrate by using silicon nitride (Si
The TFTs are connected at the intersections of both bus lines, which are arranged so as to intersect in the X and Y directions through an interlayer insulating film made of N) or the like. Moreover, when an amorphous silicon (a-Si) layer is used as the operating semiconductor layer of the TFT, a silicon nitride film (SiN) or a silicon nitride oxynitride (P-CVD) film is used as the gate insulating film. A SiNO) film was used.

In the figure, 6 is a channel protective film made of SiN.
Membrane, 8 shows the drain electrode (left side) and source electrode (right side) of the TFT. 5 (A) to 5 (E) are cross-sectional views illustrating a conventional process for manufacturing a TFT element.

The left side of the figure is the TFT section, and the right side is the corresponding auxiliary capacitance section. As shown in FIG. 5 (A), a transparent insulating substrate, such as titanium, is sputtered on the glass substrate 1.
(Ti) film is continuously formed, and after patterning the resist film by photolithography, etching is performed by using the resist film as a mask to etch the gate electrode 2 and auxiliary capacitor lower electrode 3
To form.

In FIG. 5B, the resist film is peeled off,
By the P-CVD method, a SiN film 4 as a gate insulating film and a storage capacitor dielectric film, an a-Si film as an operating semiconductor layer 5, and a SiN film 6 as a channel protective film are continuously grown. Where the first
The second layer insulating film is composed of CVD SiN film 4 and atomic layer deposition (AL
D) Method according to alumina (Al ₂ O ₃₎ may be a stacked film of a film.

Next, patterning is performed so as to leave the channel protective film 6 directly above the gate electrode 2. In FIG. 5C, an n ⁺ -type a-Si layer 7 as a contact layer and a Ti film 8 as a source / drain electrode metal film are successively formed on the substrate.

Next, the contact layer 7 and the source / drain electrode metal film 8 are patterned to form a drain electrode (left side) and a source electrode (right side). In FIG. 5 (D), a metal film, for example, an Al film 9 is formed on the substrate and patterned to form a drain bus line.

In FIG. 5 (E), an ITO film 10 made of a solid solution of indium oxide and tin oxide is formed as a transparent electrode film on the substrate.
A film is formed, and patterning is performed leaving the storage capacitor and the source electrode, and the pixel electrode is formed. This completes the process of the main part of the TFT matrix.

[0012]

In the conventional TFT matrix, since the electrode of the auxiliary capacitance is made of metal, there is a problem that the aperture ratio of the TFT is lowered and, as a result, the transmittance of the liquid crystal panel is lowered. there were.

It is an object of the present invention to suppress the increase in the number of steps and increase the transmittance of the TFT matrix to achieve high brightness and high performance of the liquid crystal panel.

[0014]

[Means for Solving the Problems] The above problems are solved by using an atomic layer deposition (ALD) method on a transparent insulating substrate 1 and using a transparent conductive film made of a ZnO: Al film as an electrode of an auxiliary capacitance.
11 and a step of continuously forming a dielectric film 12 of an auxiliary capacitor made of Al ₂ O ₃ , and then forming a gate electrode 2 on the substrate 1, a gate insulating film 4, an operating semiconductor layer on the gate electrode 2. 5, the step of sequentially forming the channel protective film 6, then the step of patterning the channel protective film so as to leave the channel protective film directly above the gate electrode, and then the high-concentration semiconductor on the substrate. Forming a contact layer 7 and a metal film 8 in that order, then patterning the contact layer and the metal film to form a drain electrode and a source electrode, and then forming a transparent electrode on the substrate. Forming a film, patterning so that the transparent electrode film is connected to the source electrode to form the pixel electrode 10, and forming an auxiliary capacitance between the pixel electrode and the transparent conductive film. Method of manufacturing thin film transistor matrix having More is achieved.

[0015]

In the present invention, the electrode film of the auxiliary capacitor is formed of the transparent conductive film (ZnO: Al), and the auxiliary electrode film and the dielectric film (Al ₂ O ₃ ) are continuously formed by the ALD method in order to prevent an increase in the number of processes. Growing.

Therefore, since the electrode film of the auxiliary capacitance is a transparent conductive film, the aperture ratio of the TFT matrix does not decrease, and it is not necessary to pattern the electrode film of the auxiliary capacitance, and the number of steps is not increased as a whole. Absent. In addition, Zn
O: When the Al and Al ₂ O ₃ are continuously formed in the ALD apparatus _is advantageous in that the raw material gas to be used may only three types.

[0017]

【Example】

Embodiment (1): FIG. 1 is an illustration of an embodiment (1) of the present invention.

In the figure, before forming the gate electrode 2, the ZnO: Al film 11 as the transparent conductive film of the auxiliary capacitance and the Al ₂ O ₃ film as the dielectric film are used on the transparent insulating substrate 1 by the ALD method.
12 is continuously formed.

Next, an example of growth conditions of ZnO: Al / Al ₂ O ₃ will be shown. Here, DEZ is diethylzinc and TMA is trimethylaluminum.

The subsequent steps are the same as those of the conventional example except that the formation of the auxiliary capacitance electrode portion is removed. Figure 2
FIGS. 3A to 3C and FIGS. 3D to 3F are explanatory views of the embodiment (2) of the present invention.

The left side of the figure is a sectional view and the right side is a corresponding plan view. In Fig. 2 (A), the ZnO: Al film 11 as the transparent conductive film of the auxiliary capacitance and the Al as the dielectric film are formed on the transparent insulating substrate 1 on the glass substrate 1 as the transparent insulating substrate by using the ALD method. _{The 2} O ₃ film 12 is continuously formed.

Next, sputtered Ti with a thickness of 1500Å
After forming a film and patterning the resist film by photolithography, the gate electrode 2 is formed by etching using the resist film as a mask.

In FIG. 2B, the resist film is peeled off,
By the P-CVD method, SiN with a thickness of 4000 Å is used as a gate insulating film.
Film 4, an a-Si film with a thickness of 150Å as an operating semiconductor layer 5, and a SiN film 6 with a thickness of 1200Å as a channel protective film are continuously grown. Here, the gate insulating film may be a laminated film of a CVD SiN film 4 and an alumina (Al ₂ O ₃ ) film formed by the atomic layer deposition method.

In FIG. 2C, patterning is performed so that the channel protection film 6 immediately above the gate electrode 2 remains. Figure 3
In (D), the thickness of the contact layer on the substrate is 600Å
The n ⁺ type a-Si layer 7 and the metal film 8 for the source / drain electrode consisting of a Ti film having a thickness of 1500 Å are continuously formed.

Next, the SiN film 4, the a-Si layer 5, and the n ⁺ -type a-Si
Layer 7 and the Ti film are patterned to form the drain and source electrodes. The difference between this step and Example (1) and the conventional step is that the SiN film 4 other than the TFT part is removed.

Therefore, in the embodiment (2), the dielectric film of the auxiliary capacitance is only the Al ₂ O ₃ film 12, which has an advantage of increasing the capacitance. In Fig. 3 (E), a metal film such as an Al film is formed on the substrate.
9 is deposited and patterned to form a drain bus line.

In FIG. 3 (F), an ITO film 10 is formed as a transparent electrode film on the substrate, and is formed on the storage capacitor portion and the source electrode 8S.
The pixel electrode is formed by patterning with leaving. Above
The process of the main part of the TFT matrix is completed.

[0028]

According to the present invention, it is possible to suppress an increase in the number of steps in manufacturing a TFT device and increase the transmittance of the TFT matrix, thereby contributing to higher brightness and higher performance of the liquid crystal panel. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of Embodiment 2 of the present invention (1)

FIG. 3 is an explanatory diagram (2) of the second embodiment of the present invention.

[Figure 4] Explanatory drawing of the TFT matrix

FIG. 5 is a cross-sectional view illustrating a manufacturing process of a conventional TFT device.

[Explanation of symbols]

1 Transparent insulating substrate, glass substrate 2 Gate electrode, Ti film 3 Storage capacitor lower electrode 4 Gate insulating film, SiN film 5 Operating semiconductor layer, a-Si film 6 Channel protective film, SiN film 7 Contact layer, n ⁺ type a -Si layer 8 Metal film for source / drain electrode Ti film 9 Al film on drain bus line 10 ITO film on pixel electrode 11 Transparent conductive film to be the electrode film of auxiliary capacitance ZnO: Al film 12 Dielectric film of auxiliary capacitance Al ₂ O ₃ film

Claims (1)

[Claims] 1. A transparent insulating substrate (1) is prepared by using an atomic layer deposition (ALD) method to form a ZnO: Al electrode serving as an auxiliary capacitance electrode.
A step of continuously forming a transparent conductive film (11) made of a film and a dielectric film (12) of an auxiliary capacitor made of Al ₂ O ₃ , and then forming a gate electrode (2) on the substrate (1). Forming the gate insulating film (4), the operating semiconductor layer (5), and the channel protective film (6) in that order, and then leaving the channel protective film directly above the gate electrode, A step of patterning the channel protective film, a step of sequentially forming a contact layer (7) made of a high-concentration semiconductor and a metal film (8) on the substrate, and then a step of forming the contact layer and the metal film. Patterning, forming a drain electrode and a source electrode,
Next, a transparent electrode film is formed on the substrate, and the pixel electrode (10) is formed by patterning the transparent electrode film so as to connect the transparent electrode film to the source electrode. And a step of forming a storage capacitor between them, the method of manufacturing a thin film transistor matrix.