JPH07114281B2 - Driver-Built-in active matrix substrate - Google Patents

Description

The present invention relates to a structure of an active matrix substrate with a built-in driver in which a thin film transistor is formed on a transparent insulating substrate.

[Conventional technology]

In recent years, a MOS type thin film transistor using a semiconductor thin film deposited on an insulating substrate as an active region has improved in performance not only as an optical switch of a pixel of a liquid crystal display device but also as a peripheral drive circuit. However, in a device using an insulating substrate, how to dissipate the charge generated on the surface of the insulating substrate to the outside to prevent the dielectric breakdown of the thin film transistor is a problem. Particularly in a device such as a liquid crystal display device having a large panel display area, it is important to prevent charge-up on the substrate surface during the manufacturing process.

FIG. 2 is a schematic diagram of an active matrix substrate with a built-in driver for liquid crystal display, which is composed of thin film transistors arranged in a matrix on a transparent insulating substrate and a peripheral driving circuit. 1 (G _{1 to} G _m ) is a gate line that is a timing line, 2 (S _{1 to} S _n ) is a source line that is a data line, and 3 thin film transistors and 4 pixel electrodes are gate lines, It is located at the intersection of the source lines. Reference numeral 5 is a timing line drive circuit, and 6 is a data line drive circuit. In this figure, the case of double-sided drive is shown.

FIG. 3 is a plan view (a) and a cross-sectional view (b) in the vicinity of the outer periphery of the conventional active matrix substrate with a built-in driver for liquid crystal display constructed as the schematic diagram. CVD for depositing crystals or amorphous materials on transparent insulating substrate 7 through chemical reaction
The polycrystalline silicon thin film 8 is deposited by the method. next,
After patterning the polycrystalline silicon thin film, a gate insulating film 9 is formed, and a gate electrode 10 and a gate line 1 using a metal or a polycrystalline silicon thin film are simultaneously formed on the gate insulating film 9 including in the drive circuit. Next, using the gate electrode 10 and the resist as a mask, P-type impurity ions and N-type impurity ions are selectively ion-implanted to form source / drain regions of P-type and N-type thin film transistors. Next, the interlayer insulating film 11 is laminated by the CVD method, and the contact hole 12
After opening, a transparent conductive film is deposited, a pixel electrode 4 is formed, and a metal is deposited to form the source line 2 and wirings in the peripheral timing line driving circuit 5 and data line driving circuit 6. .

[Problems to be solved by the invention]

However, in the above-mentioned conventional technique, since there is no escape route for the charges charged up on the transparent insulating substrate in the step of ion implantation, dielectric breakdown of the thin film transistor is likely to occur.
Therefore, at the time of ion implantation, an implantation method in which implanted ions are neutralized by thermoelectrons in the vicinity of the surface of the substrate is adopted, but complete neutralization is difficult and light damage of unknown extent occurs. With respect to such damage, the thin film transistor for driving the pixel only needs to sacrifice only the pixel by cutting with a laser or the like. However, if there is even one defective thin film transistor in the peripheral driving circuit portion, there is a problem that malfunction occurs. Therefore, the present invention solves such a problem, and an object of the present invention is to provide a peripheral drive circuit in which the dielectric breakdown resistance of a thin film transistor is increased.

[Means for solving problems]

The active matrix substrate with a built-in driver according to the present invention is characterized in that the peripheral driving circuit is surrounded by conductive film wiring, and a conductive film region is provided around the substrate to short-circuit both.

[Action]

According to the above structure of the present invention, the drive circuit is shielded by the wiring of the conductive film, and the charge up from the display portion occupying a large area can be dissipated to the outside by grounding the periphery of the substrate. Therefore, damage to the thin film transistor in the driver circuit can be eliminated.

〔Example〕

FIG. 1 is an embodiment of the present invention and is a plan view of the vicinity of the outer periphery of an active matrix substrate with a built-in driver for liquid crystal display. Although it is formed by the same process as the conventional example of FIG. 3, compared with FIG. 3, the drive circuit is surrounded by the shield wiring 13 made of the same material as the gate line in FIG. The thin film transistor is completely shielded. Further, since the shield wiring 13 is connected to the conductive film 14 provided in the periphery of the transparent insulating substrate, the charge charged up by ion implantation or the like can be dissipated to the outside by grounding the periphery of the substrate, thereby sufficiently preventing dielectric breakdown. be able to. Further, the shield wiring 13 may be formed of the same material as the gate line at the same time as in the present embodiment, but it is not necessary to use the same material and a different kind of conductor film may be used. Further, the shield wiring 13 may be formed in the same layer as the gate wiring layer of the thin film transistor in the drive circuit.

The wiring width is sufficient if it is 10 μm, the occupied area is small, and the number of steps does not increase, which is advantageous.

〔The invention's effect〕

As described above, according to the present invention, the peripheral drive circuit is shielded by the wiring of the conductive film, and the dielectric breakdown of the thin film transistor in the drive circuit due to the charged surface charge generated by ion implantation or the like. Has the effect of preventing Also, it is useful for preventing damage even in a cleaning process using oxygen plasma or the like.

[Brief description of drawings]

FIG. 1 is a plan view of the vicinity of the outer periphery of an active matrix substrate with a built-in driver for liquid crystal display of the present invention. FIG. 2 is a schematic diagram of an active matrix substrate with a built-in driver for liquid crystal display. FIG. 3 is a plan view (a) and a sectional view (b) in the vicinity of the outer periphery of a conventional active matrix substrate with a built-in driver for liquid crystal display. 1 ... Gate line (timing line) 2 ... Source line (data line) 3 ... Thin film transistor 4 ... Pixel electrode 5 ... Timing line drive circuit 6 ... Data line drive circuit 7 ... Transparent insulating substrate 8 ... … Polycrystalline silicon thin film 9 …… Gate insulating film 10 …… Gate electrode 11 …… Interlayer insulating film 12 …… Contact hole 13 …… Shield wiring 14 …… Conductive film

Claims (3)

[Claims] 1. A plurality of data lines and timing lines are arranged so as to intersect with each other, and a thin film transistor is arranged in the vicinity of an intersection with the data line and the timing line. The thin film transistor is connected to a pixel electrode. In an active matrix substrate with a built-in driver in which a drive circuit for driving the data line or the timing line is formed at the ends of the data line and the timing line, the drive circuit is provided around the drive circuit. A shield wiring that surrounds the circuit and is electrically insulated from the drive circuit is formed, a conductive film is formed in the peripheral portion of the substrate, and the shield wiring and the conductive film are electrically connected to each other. An active matrix substrate with a built-in driver. 2. The active matrix substrate with a built-in driver according to claim 1, wherein the shield wiring is the same layer as a gate wiring layer of a thin film transistor in the drive circuit. 3. The active matrix substrate with a built-in driver according to claim 1, wherein the shield wiring is the same layer as the gate wiring layer of the thin film transistor.