JPH0353512Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a switching element, and more particularly to a wiring method for a switching element formed by arranging a large number of thin film transistors.

[Prior art and its problems] Thin film transistors using amorphous semiconductors such as amorphous silicon as the semiconductor active layer can be easily made large in area, so they have recently attracted attention as switching elements for large area devices such as contact image sensors. The device is

A typical example of the element structure of a thin film transistor is a staggered structure in which a semiconductor active layer made of amorphous silicon is sandwiched between source and drain electrodes and a gate electrode, as shown in FIG.

In this structure, for example, a gate electrode 102 is formed on a glass substrate 101, a gate insulating film 103 is formed thereon by a CVD method, and then an amorphous silicon i layer 104 is formed as a semiconductor layer.
Then, an amorphous silicon n ⁺ layer 105 is formed, and finally a source electrode 106 and a drain electrode 107 are formed. When patterning the source and drain electrodes, it is desirable that the edges of the source and drain electrodes match and align with the edges of the gate electrode, which not only requires high accuracy in mask alignment, but also If the edge of the drain electrode is outside the edge of the gate electrode, there will be a part where no channel can be formed and the transistor will remain off; if it is inward, the source and drain electrodes will overlap with the gate electrode. However, there was a problem in that the coupling capacity between the two increased and the response speed became slow.

To solve these problems, a self-aligned thin film transistor has been proposed in which, for example, the source/drain electrodes are patterned by applying a resist and then irradiating light from the substrate side using the gate electrode as a mask to form a resist pattern. has been done.

However, even with regard to this self-aligned thin film transistor, when a large number of thin film transistors are integrated to form a switching element as shown in FIG. There is a problem in that the capacitance generated by the crossing has substantially the same effect as the parasitic capacitance described above.

This invention was made in view of the above-mentioned circumstances,
It is an object of the present invention to provide a thin film transistor switching element with good operating characteristics by eliminating capacitance caused by the intersection of a gate electrode wiring and a source and drain electrode wiring.

[Means for solving the problem] Therefore, in the present invention, in a switching element formed by commonly connecting the gate electrodes of a large number of thin film transistors, the common gate wiring that commonly connects the gate electrodes is one wire that includes each gate electrode. Each source electrode wiring is arranged on one side of the line segment, and each drain electrode wiring is arranged on the other side with respect to the line segment.

[Operation] That is, each source electrode wiring and each drain electrode wiring are arranged on one side of the common gate wiring that commonly connects the gate electrodes, so there is no crossing of wiring patterns. This makes it possible to suppress the generation of capacitance.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a top view showing a thin film transistor switching element in which a common gate wiring for commonly connecting gate electrodes has a meander pattern.

This switching element consists of a large number of thin film transistors T ₁ to Tn arranged in a row on a glass substrate (not shown), and each thin film transistor
The pattern of the gate wiring 1 that commonly connects the gate electrodes G of T ₁ to Tn is a single unbranched line segment consisting of a meander pattern (zigzag pattern), and each source wiring 2 and drain wiring 3 are connected upwardly and It is arranged facing downward.

Each of the thin film transistors T ₁ to _{T o} has a normal staggered structure, and includes a gate electrode G made of a chromium thin film disposed on a glass substrate, a gate insulating film (not shown) made of a silicon oxide film, Semiconductor active layer A consisting of hydrogenated amorphous silicon i-layer (a-Si:H), hydrogenated amorphous silicon
This is a self-aligned thin film transistor in which an ohmic contact layer (not shown) made of an n ⁺ layer and source and drain electrodes S and D made of aluminum thin films are sequentially laminated. and,
The gate wiring 1 is the gate electrode G, and the source/drain wirings 2 and 3 are the source/drain electrodes S and D.
and are formed in the same process, respectively.
It is composed of a chromium thin film and an aluminum thin film.

According to such a wiring structure, since there is no crossing between the gate wiring and the source/drain wiring, the capacitance due to crossing becomes 0, and a switching element with good operating characteristics can be obtained.

Further, as a modification of the present invention, as shown in FIG. 2, the thin film transistors T ₁ to _{T o} may be arranged in a stepwise manner to form the gate wiring 11 having a stepwise meander pattern. The source/drain wirings 12 and 13 may be arranged upward and downward, respectively, as in the previous embodiment.

As another example, as shown in FIG. 3, the thin film transistors are arranged so that the gate electrodes of each of the thin film transistors T ₁ to _{T o} are in a straight line, and the gate electrodes are shared by a straight gate wiring 21. Connected structures are also effective. At this time, the source/drain wirings 22 and 23 are arranged upward and downward, respectively, and have the simplest structure as a wiring pattern.

In the embodiment, a thin film transistor with a staggered structure is used, but the present invention is not necessarily limited to this, and the present invention is also effective for thin film transistor switching elements with other structures such as a planar structure.

Further, the shape of the wiring pattern is not limited to the embodiment and can be changed as appropriate.

[Effect] As explained above, according to the switching element of the present invention, the gate electrodes of each thin film transistor are commonly connected by a wiring pattern (gate wiring) consisting of one unbranched line segment, and each source and Connect the lead line (source/drain wiring) from the drain electrode to the gate wiring,
Because they are formed in different directions,
There is no capacitance due to crossings between wires, making it possible to improve operating characteristics.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a wiring structure of a thin film transistor switching element according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing a modification of the present invention, and FIG. An example diagram, FIG. 5, is a diagram showing the wiring structure of a conventional thin film transistor switching element. 101...Glass substrate, 102...Gate electrode, 1
03... Gate insulating film, 104... Amorphous silicon i layer, 105... Amorphous silicon n ⁺ layer,
106... Source electrode, 107... Drain electrode, G
... Gate electrode, S... Source electrode, D... Drain electrode, A... Semiconductor active layer, 1, 11, 21... Gate wiring, 2, 12, 22... Source wiring, 3, 13,
23...Drain wiring.

Claims (1)

[Claims for Utility Model Registration] (1) In a switching element formed by commonly connecting the gate electrodes of a plurality of thin film transistors, the common gate wiring that commonly connects each gate electrode is a single unbranched wiring that includes each gate electrode. Each source electrode wiring is arranged on one side with respect to the common gate wiring, and each drain electrode wiring is arranged on the other side with respect to the common gate wiring. A switching element characterized by: (2) The switching element according to claim 1, wherein the thin film transistors are arranged in a line, and the common gate wiring forms a meandering pattern.