JP3196344B2 - Active matrix substrate manufacturing method - 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 for manufacturing a high-definition small panel used for a video movie or the like.

[0002]

2. Description of the Related Art In a liquid crystal display panel, a data line (signal line) for supplying an image signal and a gate line (scan line) for transmitting a scanning signal are arranged in a grid, and each image area is defined. Liquid crystal is sealed between the transparent substrate in one direction and the transparent substrate in the other direction on which the common electrode is formed, and controls the potential applied between the common electrode and the pixel electrode in each pixel region. In addition, the alignment state of the liquid crystal in each pixel region is changed. Such a liquid crystal display panel device has a structure shown in FIG. 3 as an example, and the device is formed on a flat transparent insulating substrate.

[0003]

However, as shown in FIG. 3, since the data line 9 protrudes from the transparent conductive electrode 8, the rubbing process (for the liquid crystal to lie or stand along a certain direction). When the rubbing roller is rubbed in a certain direction using rayon to align the liquid crystal in a row), the pressure applied to the rubbing roller is not sufficiently applied to the transparent conductive electrode 8, so that the alignment of the liquid crystal is There has been a problem that it becomes partially uneven.

As a countermeasure against this, a method has conventionally been used in which a groove is formed on an insulating substrate and a device is formed in the groove. The conventional method of forming this groove is to first form a SiO ₂ film as an insulating film on a substrate by a CVD apparatus or the like, and then form a groove by patterning into a specific shape by photolithography and etching. Was.
However, for etching, wet etching is mainly used from the viewpoint of productivity. Since the depth of the groove was controlled by the etching time, the depth did not become constant (± 20%) even after etching for the same time due to a change in the film quality of SiO ₂ , deterioration of the etching solution, and the like. In addition, since the etched surface has fine irregularities, the characteristics of the TFT element formed thereon are extremely low.

[0005]

In order to solve the above-mentioned problems, a method of manufacturing an active matrix substrate according to the present invention comprises the steps of: forming an amorphous or polycrystalline silicon film on a substrate; A step of forming a groove by removing a part of the polycrystalline silicon film; a step of oxidizing the amorphous or polycrystalline silicon to form an oxide film; and a thin film transistor including a source region and a drain region in the groove. Forming a data line in the groove, and forming a transparent conductive electrode on the oxide film outside the groove.

[0006]

According to the present invention, the depth of the groove is uniform, the surface of the groove is not uneven, and the characteristics of the thin film transistor are stabilized. Such characteristics could not be realized with grooves formed by etching. According to the structure of the thin film transistor realized by the present invention, the characteristics of the thin film transistor can be stabilized as described above, and since the protrusion of the data line is eliminated, the pressure of the rubbing roller is sufficiently applied to the transparent conductive electrode, The alignment of the liquid crystal becomes uniform.

[0007]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the device structure of the present invention,
FIG. 2 shows a groove forming step according to the embodiment of the present invention. As a first step of forming a groove, as shown in FIG. 2A, an amorphous or polycrystalline silicon film 12 is formed on the transparent insulating substrate 1 by CVD or the like. The film thickness at this time is about 5000 °. As a second step, FIG.
As shown in FIG. 1, a specific pattern is formed on the amorphous or polycrystalline silicon film 12 by photolithography. Next, as a third step, steam oxidation is performed as shown in FIG. This was performed at 1100 ° C. for 2 hours in a steam atmosphere using a diffusion furnace or the like. The oxide film 10 is formed by this process, and the depth of the groove is set to about 1 micron. Thus, the groove 14 is completed. The bottom surface of the groove 14 is smooth,
Since the film is formed by oxidation, the thickness of the film is uniform. Therefore, if a device is formed here, the TFT characteristics are stabilized. First, a polycrystalline silicon film 13 is placed in this groove at about 600 ° C.
₄ is decomposed and deposited at 1000 °. Next, the polycrystalline polysilicon film 13 is formed by photolithography so as to extend from inside the groove (below the step) to outside the groove (above the step). Next, a part of the polycrystalline silicon film 13 is thermally oxidized to form a gate oxide film 5 of about 1000 °, and then the polycrystalline silicon film 5 which is to
Å Deposit. This polycrystalline silicon film 13 is subjected to phosphorus diffusion at 850 ° C. using phosphorus oxychloride in an atmosphere of oxygen and nitrogen. Next, the polycrystalline silicon film 13 diffused with phosphorus
Is dry-etched using a CF ₄ —O ₂ -based gas to form a gate electrode 6. Next, phosphorus ions are implanted into the polycrystalline silicon film 13 using the gate electrode 6 as a mask.
A source region 2 and a drain region 3 are formed. This time N
Although a channel transistor is formed, if a P-channel transistor is desired to be formed, boron ions may be similarly implanted into the polycrystalline silicon film 13. Next, an interlayer insulating film 7 is deposited by CVD at about 8000.degree., And then heat-treated at 1000.degree. C. for 20 minutes in a nitrogen atmosphere. This is for the purpose of activating ions implanted for forming the source 2 and drain 3 regions and for baking the interlayer insulating film 7. Next, a transparent conductive electrode film is deposited by a sputtering method, and is patterned to form a pixel electrode 8 on the film 10 formed by steam oxidation. Finally, aluminum is deposited at a thickness of 5000 ° by a sputtering method, and is patterned to form an aluminum electrode (data line 9) in the groove 12, thereby completing the process.

In the groove 12 and the device 11 formed by the above steps, the bottom surface of the groove 12 is smooth, and the thickness of the oxide film formed by the steam oxidation is uniform. The device 11 formed in the groove 12 is formed at a position where the data line 9 is lower than the transparent conductive electrode 8.

[0009]

As described above, the bottom surface of the groove 12 formed by the process of the present invention is smooth, and the depth of the groove 12 is uniform because the film is formed by steam oxidation. Therefore, the characteristics of the TFT device 11 formed in the groove 12 are stabilized. Also, the data line 9 is inside the groove (below the step),
Since the transparent conductive electrode 8 is formed outside the groove (on the step), the pressure applied to the rubbing roller during the rubbing treatment is sufficiently applied to the transparent conductive electrode 8 so that the alignment of the liquid crystal is uniform. Become.

[Brief description of the drawings]

FIG. 1 is a device structure of the present invention.

FIG. 2 shows a process for forming a groove for forming a device.

FIG. 3 shows a conventional device structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz substrate 2 Source region 3 Drain region 4 Channel region 5 Gate oxide film 6 Gate region 7 Interlayer insulating film 8 Transparent conductive electrode (ITO) 9 Data line (aluminum) 10 Steam oxide film 11 TFT device 12 Polycrystalline silicon film 13 Many Crystal silicon film 14 groove

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1362 G02F 1/1343 G02F 1/1333 H01L 29/78

Claims (1)

(57) [Claims] A step of forming an amorphous or polycrystalline silicon film on a substrate; a step of removing a part of the amorphous or polycrystalline silicon film to form a groove; Oxidizing polycrystalline silicon to form an oxide film; forming a thin film transistor including a source region and a drain region in the trench; forming a data line in the trench; and oxidizing outside the trench. Forming a transparent conductive electrode on the film. A method for manufacturing an active matrix substrate, comprising: