JPH07168203A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To assure sufficient intensity of light emission spectra and to detect the end point of etching by providing this device with dummy regions corresponding to contact holes. CONSTITUTION:The first dummy region 306 is opened simultaneously with the first contact hole connecting the source electrode and source line of a thin- film transistor and a photoresist 310 as a mask. The etching is executed by reactive ion etching RIE. The photoresist 310 is removed after the end of the etching and thereafter,a second interlayer insulating film 308 is formed. Next, a photoresist 311 for opening the second contact hole is formed and the second dummy region 309 are opened simultaneously with the second contact hole. The etching is executed by RIE. Next, the photoresist 311 is removed and pixel electrodes are formed. As a result, the detection of the end point of the etching is facilitated.

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 liquid crystal display device, and more particularly, to an etching region and an etching method for opening a contact hole.

[0002]

2. Description of the Related Art Liquid crystal display devices are becoming higher in definition and resolution year after year, and the production volume and market scale are expanding. In liquid crystal display devices used for viewfinders and projectors, the panel size and resolution have been increasing at the same time to reduce costs, and devices including thin film transistors have been miniaturized.
The number of layers is increasing. An example of the structure of such a high definition device is shown in FIG. In FIG. 2, a glass substrate 201
The semiconductor layer 202 is provided thereover, and the gate insulating film 203 is provided thereon. The gate electrode 204 is on the gate insulating film and also serves as a gate line. Reference numeral 205 denotes a first line that electrically insulates the source line or the lead line 207 of the source electrode from the gate line 204.
Is an interlayer insulating film. Reference numeral 208 denotes a second interlayer insulating film that insulates the source line 207 and the pixel electrode 210. The source electrode 207 is composed of the gate insulating film 203 and the first interlayer insulating film 20.
It is connected to the source electrode formed in the semiconductor layer 202 through the first contact hole 207 opened in 5. The pixel electrode 209 is electrically connected to the drain electrode formed in the semiconductor layer 202 through the second contact hole 209 opened in the gate insulating film 203, the first interlayer insulating film 205, and the second interlayer insulating film 208. Connected to each other. In such a structure, the pixel electrode is electrically insulated from all other different wirings and electrodes, and the area thereof can be maximized as long as the insulation between adjacent pixel electrodes is secured. That is, with such a structure, a bright liquid crystal display device having high definition and a large aperture ratio can be obtained.

[0003]

However, since the second contact hole 209 shown in FIG. 2 is opened in the three kinds of insulating films as described above, it is a problem to control the sectional shape of the contact hole. Becomes Further, due to the demand for higher definition and higher aperture ratio of the liquid crystal display device, it is necessary to miniaturize each component of the element. That is, the size of the contact hole must be reduced and the above problems must be solved at the same time. Controlling the cross-sectional shape and dimensions of the contact hole is important for preventing disconnection of the wiring layer in that portion and ensuring electrical continuity. In the miniaturization, it is necessary to control the cross-sectional shape and size of the opening of the first contact hole as well. Although these problems are more severe in the second contact hole than in the first contact hole, they are related to each other and need to be solved at the same time in view of the entire manufacturing process of the device.

[0004]

In order to solve the above problems, the present invention provides a plurality of gate lines, a plurality of source lines, and a plurality of thin film transistors formed at their intersections on an insulating substrate, A liquid crystal display device comprising, as constituent elements, a first contact hole in which a source electrode of a thin film transistor is connected to the source line, and a second contact hole in which a drain electrode of the thin film transistor is connected to a pixel electrode, In the etching process for forming the first contact hole, the first contact hole and the first dummy region are simultaneously etched, and in the etching process for forming the second contact hole, It is characterized in that the second contact hole and the second dummy region are simultaneously etched.

[0005]

EXAMPLE An example of the present invention will be described with reference to FIG. Figure 3
Shows the structure of the first and second dummy regions corresponding to the above-mentioned first and second contact holes and the manufacturing process including the etching process. In FIG. 3, 306 is a first dummy region corresponding to the first contact hole 206 shown in FIG. 2, and 309 is a second dummy region corresponding to the second contact hole 209 shown in FIG. Area. In FIG. 3A, 302 is a semiconductor layer that is formed in the first dummy region and is simultaneously formed of the same material as the source region of the thin film transistor formed in the semiconductor layer, and 302 ′ is the second dummy region. And a drain region of a thin film transistor which is formed in the semiconductor layer and is simultaneously formed of the same material as the drain region of the thin film transistor. Although 302 and 302 'are not connected in the figure, they may be connected. Reference numeral 303 denotes a gate insulating film formed of the same material as the gate insulating film (203 in FIG. 2) of the thin film transistor at the same time. The gate electrode (204 in FIG. 2) formed on the gate insulating film is not formed in the dummy region. Ion implantation for the source / drain regions of the thin film transistor is simultaneously performed on the dummy region. 305 is simultaneously formed of the same material as the first interlayer insulating film (205 in FIG. 2) that insulates the gate line and the source line. Reference numeral 306 denotes a first contact hole (see FIG. 2) that connects the source electrode and the source line of the thin film transistor.
206) and the photoresist 310 is used as a mask at the same time. The etching is performed by reactive ion etching (hereinafter abbreviated as RIE). After the etching is completed, the photoresist 310 is removed, and then, as shown in FIG.
A second interlayer insulating film 308 is formed as shown in (b). Next, as shown in FIG. 3C, a photoresist 311 for opening the second contact hole is formed, and a second dummy region 309 is opened at the same time as the second contact hole. The etching is performed by RIE. Next, the photoresist 311 is removed and a pixel electrode is formed.

[0006] The point of the present invention relates to a method for detecting the end point of etching in RIE. The sizes of the first and second contact holes are required to be 3 to 2 μm □ or less in accordance with the miniaturization of devices as described above. On the other hand, the detection of the etching end point by RIE is performed by detecting the emission spectrum of the reaction product during the etching, so that a certain amount of the reaction product is required. However, when the area of the contact hole becomes small, the amount of the reaction product becomes small, and therefore, the intensity of the target emission spectrum becomes small and it becomes difficult to detect the etching end point. However, in the present invention, since the dummy region corresponding to the contact hole is provided, it is possible to secure a sufficient intensity of the emission spectrum, and therefore it is possible to detect the etching end point. Further, the first and second dummy regions can be set so as not to impair the effective area of the substrate for forming the panel, such as a region around the substrate.

The present invention relating to the method of setting the dummy region corresponding to the contact hole will be described with reference to FIG. In FIG. 1, 101 is an insulating substrate, 112 is a liquid crystal panel region, 106 is the first dummy region corresponding to the first contact hole, and 108 is the second dummy region corresponding to the second contact hole. 2 dummy areas. The first and second dummy regions also serve as a dicing region for cutting the panel in the process of assembling the liquid crystal panel. In FIG. 1, the first dummy region 106 is a vertical dicing region, and the second dummy region 108 is a horizontal dicing region. However, the first and second dummy regions are specially divided. There is no limit. Desirably, the areas of the first and second dummy regions are substantially the same,
Moreover, there is no bias in the distribution when viewed from the entire substrate.
Further, in FIG. 1, 113 is a dead region which is not desirable for panel formation because it is easily scratched during the manufacturing process, but this region can also be used as the dummy region.

Next, a method of etching the contact hole according to the present invention will be described with reference to FIG. FIG. 4 shows a sectional shape of the second contact hole. 401
Is an insulating substrate, 402 is a drain region of a thin film transistor, 403 is a gate insulating film, 405 is a first interlayer insulating film for insulatingly separating a gate line and a source line, and 408 is a second interlayer for insulatingly separating a source line and a pixel electrode. The insulating films 411 are photoresists for opening the second contact holes. In the etching of the contact hole, a part of the second interlayer insulating film 408 is first etched with a buffered hydrofluoric acid solution to obtain a shape of 409a. Next, the remaining portion of the second interlayer insulating film, the first interlayer insulating film 405, and the gate insulating film 402 are etched by RIE.

The point of the present invention shown in FIG.
The shape of the contact hole is formed as shown in the figure to prevent disconnection at this portion. In order to improve the characteristics of the thin film transistor, the gate insulating film is usually made of a dense film such as a thermal oxide film of silicon.
Therefore, the etching rate is slow. A silicon oxide film formed by a CVD method or the like is used as the first interlayer insulating film, but the first interlayer insulating film is densified because it is subjected to a heat treatment for activating the impurities that are ion-implanted to form the source / drain regions, and the etching rate is It is the second slowest after the gate insulating film. As the second interlayer insulating film, a silicon oxide film formed by a CVD method or the like is usually used on a source line formed of Al and has the fastest etching rate. The difference in etching rate between these films is several times to ten times. Like this second
Since the three types of insulating films in which the contact holes are to be opened have greatly different etching rates, it is difficult to simultaneously etch two or more layers of films while controlling the shape by wet etching. However, it is easy to partially open the second interlayer insulating film, which is the first layer, by wet etching. Further, due to isotropic etching peculiar to wet etching, the shape becomes 409a in FIG. The remaining film thickness of the second interlayer insulating film has a large variation between substrates and lots because the etching rate in wet etching is large. However, in the next RIE, the etching end point can be determined by virtue of the dummy region according to the present invention, and therefore even if the remaining film thickness differs between the substrates, there is no problem such as insufficient etching.

[0010]

As described above, according to the present invention, when a fine contact hole is opened in a multi-layer insulating film having different etching rates, the cross section of the contact hole is prevented so as not to break the wiring layer in that portion. The shape can be controlled, and the etching end point can be easily detected. If this effect is replaced with a liquid crystal display device, a liquid crystal display device with high definition and high aperture ratio can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a dummy area for detecting an etching end point according to the present invention.

FIG. 2 is a cross-sectional view of a pixel thin film transistor according to the related art.

FIG. 3 is a sectional view of a dummy region in an etching process according to the present invention.

FIG. 4 is a sectional view of a dummy region in an etching process according to another embodiment of the present invention.

[Explanation of symbols]

101, 201, 301, 401 Insulating substrate 202, 302, 402 Semiconductor layer 203, 303, 403 Gate insulating film 204 Gate electrode 205, 305, 405, 208, 308, 408 Interlayer insulating film 310, 311, 411 Photoresist

Claims (9)

[Claims] 1. A plurality of gate lines, a plurality of source lines, a plurality of thin film transistors formed at intersections thereof, and a source electrode of the thin film transistors connected to the source lines on an insulating substrate. In a liquid crystal display device including a contact hole and a second contact hole in which a drain electrode of the thin film transistor is connected to a pixel electrode, in the etching process for forming the first contact hole, The first contact hole and the first dummy region are simultaneously etched, and the second contact hole and the second dummy region are simultaneously etched in the etching process for forming the second contact hole. Liquid crystal display device and manufacturing method thereof. 2. The first contact hole and the second contact hole
Said contact holes are opened by different etching steps, and at least etching for forming said first or second contact holes is performed by a method including a reactive ion etching method. The liquid crystal display device and the manufacturing method thereof. 3. The sectional structure of the first dummy region and the sectional shape of the first contact hole are the same, and the sectional structure of the second dummy region and the sectional shape of the second contact hole. 3. The liquid crystal display device according to claim 1 and the manufacturing method thereof, wherein 4. The total area of the first dummy regions is larger than the total area of the first contact holes, and the total area of the second dummy regions is larger than the total area of the second contact holes. The liquid crystal display device according to claim 1, 2 or 3, and a method for manufacturing the same. 5. The liquid crystal display device according to claim 1, wherein the first and second dummy regions are different regions from each other, and a manufacturing method thereof. 6. The first and second dummy regions,
At least a region around the panel, a dicing region for cutting the panel, or a region around the substrate is used, and the first and second dummy regions are different from each other. The liquid crystal display device and the manufacturing method thereof. 7. The first contact hole is a contact hole which is simultaneously opened in a gate insulating film, a first interlayer insulating film for insulatingly separating a gate line and a source line, and the second contact hole is a gate insulating film. 2. A contact hole that is simultaneously opened in a first interlayer insulating film that insulates and separates a film, a gate line, and a source line and a second interlayer insulating film that insulates and separates a source line and a pixel electrode.
The liquid crystal display device and the manufacturing method thereof. 8. The first contact hole is a contact hole that is simultaneously opened in a gate insulating film, a first interlayer insulating film that insulates and separates a gate line and a source line, and the first contact hole. Is first wet-etched to partially etch the first interlayer insulating film, and then reactive ion etching is performed to etch the rest of the first interlayer insulating film and the gate insulating film. The liquid crystal display device according to claim 1, and a method for manufacturing the same. 9. The second contact hole is simultaneously opened in the gate insulating film, the first interlayer insulating film for insulating and separating the gate line and the source line, and the second interlayer insulating film for insulating and separating the source line and the pixel electrode. The second contact hole is first etched by wet etching to partially etch the second interlayer insulating film, and then reactive ion etching is performed to remove the second contact hole. 2. The liquid crystal display device according to claim 1, wherein the remaining interlayer insulating film is etched, and the first interlayer insulating film and the gate insulating film are etched.