JPH05142567A - Formation of thin film - Google Patents

Abstract

PURPOSE:To provide the method for forming thin films used for production an image display device which reduces the coat by drastic simplification of process and has stable quality. CONSTITUTION:Overlap parts 7 of a conductive substrate holder 2 fixing a glass substrate 1 are formed long to the extent that these parts overlap on conductive electrode patterns 5 formed on the glass substrate 1 or a conductive mask is freshly added to the conductive substrate holder 2, by which the films are not deposited on the taking-out electrode part surface at the ends of the conductive electrode patterns 5 covered with the holder 2 or the mask added thereto and are selectively formed only in the regions exclusive thereof. In addition, the films are formed by electrically connecting the holder 2 or the mask added thereto and the conductive electrode patterns 5 formed on the glass substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention replaces a conventional cathode ray tube with a flat image display device such as a liquid crystal display which is being used as a display device such as a personal computer and a television, and a thin film forming method essential for manufacturing the same. It is about.

[0002]

2. Description of the Related Art As devices using thin film forming technology such as liquid crystal displays are required to be light, thin, short, and energy-saving, the market is expected to expand further in the future.

Among these thin film forming methods, plasma CV required especially for manufacturing a liquid crystal display will be described below.
The conventional technique will be described by taking the D method as an example.

Liquid crystal displays are manufactured by vacuum vapor deposition (eg, sputtering or plasma CV) on an insulating glass substrate.
By the method D), a conductive thin film, an insulating thin film, and a semiconductor thin film are stacked in layers to be manufactured.

FIG. 4 shows a schematic structure of a plasma CVD apparatus. A glass substrate 1 which is an object to be deposited is fixed to a metal holder 2 made of stainless steel or aluminum which also serves as a ground electrode, and is constituted by a high frequency electrode 3 facing the metal holder 2 and a high frequency power source 4 connected to the high frequency electrode 3. There is. By applying a high frequency power of 13.56 MHz between both electrodes in a low-pressure gas such as monosilane or ammonia of about 100 Pa, decomposition of the gas occurs and a desired film corresponding to the type of gas is formed on the surface of the glass substrate 1. It will be deposited on.

FIG. 5 is a sectional view showing a state where the glass substrate 1 is fixed to the holder 2. A glass substrate 1 for film formation on which an electrode pattern 5 has already been formed is sandwiched and fixed by a holder 2 and a metal back plate 6 of the same kind as the holder 2. At this time, the surface of the glass substrate 1 (the surface on which the electrode pattern 5 is formed) is different from the holder 2 in all around the glass substrate.
It has an overlapping portion 7 of about 5 mm. Normally, this part is a region not used as an element, and naturally the electrode pattern 5
Is also formed inside with a certain gap. Therefore, the film is deposited on the electrode pattern 5 as well as the metal holder 2 and the electrode pattern 5 on the glass substrate 1.
Will be formed into a film with an electrically insulated structure.

[0007]

In such a conventional method, since the film is deposited on the entire surface of the electrode pattern already formed on the glass substrate, the photolithography and etching steps are further added thereafter. The work of removing a part of the above is required, and this is one of the factors that reduce the yield of the device and increase the cost.

As another problem, in the plasma CVD method, gases such as monosilane and ammonia are discharged at a low pressure of about 100 Pa, so these gases are ionized. Therefore, when a film is formed on an insulating substrate such as glass used for a liquid crystal display, these ions adhere to the surface of the glass substrate, and the conductive electrode pattern formed on the glass substrate is charged to cause discharge. Abnormal discharge such as unevenness and sparks is generated, which is one of the causes of nonuniformity of the deposited film.

[0009]

In order to solve these conventional problems, a thin film forming method of the present invention is a conductive electrode in which an overlapping portion of a conductive substrate holder for fixing a glass substrate is formed on the glass substrate. Make it long enough to overlap the pattern.

[0010]

According to this structure, no film is deposited on the surface of the extraction electrode portion at the end of the conductive electrode pattern covered with the conductive substrate holder, and the film is selectively formed only on the other regions. At the same time, a film is formed by electrically connecting the holder and the conductive electrode pattern formed on the glass substrate.

[0011]

EXAMPLE An example of the thin film forming method of the present invention will be described.
Description will be made with reference to the cross-sectional view showing the fixed state of the glass substrate at the time of film formation by the plasma CVD method shown in FIG.

The names of the respective parts in FIG. 1 showing the thin film forming method of this embodiment are the same as those of the conventional one shown in FIG. 5, and the same parts are designated by the same reference numerals.

In the structure of this embodiment, the overlapping portion 7 of the conductive substrate holder 2 for fixing the glass substrate 1 is made sufficiently long so as to cover the end portion of the conductive electrode pattern 5 as compared with the conventional case,
The conductive substrate holder 2 and the conductive electrode pattern 5 formed on the glass substrate 1 are electrically connected. The conductive substrate holder 2 has a function as a ground electrode and the function of the back plate 6 is the same as the conventional one.

FIG. 2 is an enlarged cross-sectional view of the peripheral portion of the image display device, showing the lead-out terminal portion 1 at the end of the conductive electrode pattern.
3 and insulating protective films 15, 1 deposited on the surface thereof
The cross-sectional shape of 5'is shown as an example.

FIG. 2A shows a conventional method,
(B) shows the one according to the present embodiment.

In the conventional method of (a), since the insulating protective film 15 is deposited on the surface of the lead-out terminal portion when the thin film is formed, it is necessary to etch this portion (the cutout portion of the insulating protective film 15) in a later step. is there. Therefore, the film thickness of the insulating protective film 15 near the etched portion is substantially uniform.

On the other hand, in the present embodiment (b), due to the nature of the plasma CVD method, the thickness of the insulating protective film is 0.2 to the inside from the end of the lead terminal portion 13 masked by the metal holder 2. In the area of 10 mm, a characteristic shape of a gentle slope is shown.

In this embodiment, the overlapping portion 7 is made long, but the present invention is not limited to this, and the same effect can be obtained by separately providing a conductive mask on the holder 2 so as to cover the pattern 5.

FIG. 3 is a cross-sectional view showing a schematic structure of a lead-out terminal portion of a liquid crystal panel in which a thin film transistor (hereinafter referred to as a TFT) is built-in and a TFT portion having an inverted stagger structure. FIG. And (b) shows the one prepared by the method of the present invention.

First, the structure and manufacturing method will be briefly described by taking (a) as an example. A gate electrode 8 of Cr or the like is patterned on the glass substrate 1, and a gate insulating film 9 and a semiconductor layer 10 of amorphous silicon or the like are formed into a thin film by a plasma CVD method. The semiconductor layer 10 is patterned and the source electrode 11 and the drain electrode 12 are formed on both ends thereof. After that, the extraction electrode pad 13 and the pixel electrode 14 are formed of indium tin oxide (ITO), and finally the insulating protective film 15 of silicon nitride is formed by the plasma CVD method. Further, in order to drive this panel, a lead electrode 17 is connected to the electrode pad 13 via the conductive particles 16, and this is connected to an external IC (not shown). Here, the portion composed of the gate electrode 8, the gate insulating film 9 and the semiconductor layer 10 is a TFT portion having a MOS structure, and the uniformity of the gate insulating film and the semiconductor layer formed by the plasma CVD method is important. At the same time, attention must be paid to the deterioration and destruction of the characteristics of the element due to static electricity.

In the conventional method shown in FIG. 3A, when the gate insulating film 9 and the insulating protective film 15 are formed by the plasma CVD method, they are deposited on the entire surface of the gate electrode 8 and the electrode pad 13. In a later step, it is necessary to form a contact window for the gate insulating film 9 for connecting the gate electrode 8 and the electrode pad 13 and a contact window for the insulating protective film 15 for contacting the electrode pad 13 and the conductive particles 16. is there. Moreover, these contact windows are formed by insulating films 9 and 15
Is chemically reacted in a liquid or gas to remove it, but at this time reaction products are formed on the surface of the underlying electrode, and organic substances are attached during resist removal, resulting in the loss of contact between electrodes. ..

However, according to the present invention, as shown in FIG. 3B, when the gate insulating film 9 and the insulating protective film 15 are deposited by the plasma CVD method, the gate electrode 9 is removed from the end portion of the glass substrate 1. Since the structure is partially covered with the substrate holder, the insulating film is not selectively deposited on the electrode surface in this part, and the contact window forming step at least at two places is unnecessary. The actual manufacturing process of the liquid crystal panel is more complicated.
The number of masks manufactured with 9 masks can be reduced to 4 to 6 masks, and a great simplification of the process can be realized.

Further, since the formation of the contact window is not necessary, the electrode surface is not exposed to the chemical treatment and is always clean, the contact property between the electrodes is greatly improved, and the yield and reliability of the element are improved. The effect is very great.

Further, in the conventional method, the gate electrode 8 and the electrode pad 13 corresponding to the conductive electrode pattern 5 shown in FIG. 5 are not in contact with the conductive substrate holder 2 which also functions as a ground electrode when the film is formed by plasma CVD. In addition, the surface potential of the glass substrate 1 becomes unstable, and unevenness of the film and deterioration or destruction of device characteristics are likely to occur. However, according to the method of the present invention, as shown in FIG. 1, the conductive electrode pattern 5 formed on the glass substrate 1 is always in contact with the conductive substrate holder 2 which is the ground electrode and is kept at the same potential. The potential on the surface of the glass substrate is very stable, abnormal discharge can be avoided, the uniformity of the film is greatly improved, and damage to the device due to discharge can be significantly reduced.

[0025]

As described above, according to the present invention, a film is not selectively formed on the electrode pattern in the peripheral portion of the glass substrate covered with the holder. Since the work of removing the film for taking out the electrode is unnecessary, a great simplification of the process can be realized.

Furthermore, even in an ionic gas atmosphere during film formation, the conductive electrode pattern formed on the glass substrate is always kept at the same potential as the holder serving as the ground electrode, and the potential of the glass substrate surface is extremely high. It is stable, and abnormal discharge can be avoided, and the uniformity of the film is greatly improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fixed state of a glass substrate at the time of forming a thin film in one embodiment of the present invention.

FIG. 2A is a sectional structure view of a peripheral portion of a conventional image display device. FIG. 2B is a sectional structure diagram of a peripheral portion of an image display device according to an embodiment of the invention.

FIG. 3A is a sectional structure view of a peripheral portion of a TFT liquid crystal panel prepared by a conventional method. FIG. 3B is a sectional structure view of a peripheral portion of a TFT liquid crystal panel prepared by the method of the present invention.

FIG. 4 is a schematic configuration diagram of a plasma CVD apparatus.

FIG. 5 is a cross-sectional view showing a fixed state of a glass substrate when forming a conventional thin film.

[Explanation of symbols]

 1 Glass Substrate 2 Conductive Substrate Holder 5 Conductive Electrode Pattern Formed on Glass Substrate 6 Back Plate 7 Overlapping Area of Glass Substrate and Substrate Holder

Claims (1)

[Claims] 1. A method of fixing an insulating substrate with a conductive substrate holder and forming a thin film on the insulating substrate by a vacuum deposition method, the method including overlapping with an electrode pattern formed on the conductive substrate holder. A thin film forming method of forming a thin film by fixing the insulating substrate with the conductive substrate holder as described above.