JPH04233512A - Production of active matrix substrate - Google Patents

Abstract

PURPOSE:To realize an active matrix substrate having good TFT characteristics by ion implantation method. CONSTITUTION:P<+> ions are implanted to the upper side of a substrate having a resist 11 remaining on a channel protective film 5. This prevents implantation of impurities in the channel protective film 5. Thereby, leaking of current between contact layers 6a, 6b and source electrode 7 and between contact layers and a drain electrode 8 is precented.

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 an active matrix substrate used in liquid crystal display devices and the like.

0002

2. Description of the Related Art FIG. 3 shows a conventional example of a method for manufacturing this type of active matrix substrate. As shown in FIG. 3(a), a gate electrode 2 is first formed on a glass substrate 1, and then , forming a gate insulating film 3 on the gate electrode 2;
After that, a semiconductor layer 4 is formed on the insulating film 3. Then,
A channel protective film 5 is patterned in a portion of the semiconductor layer 4 corresponding to the upper part of the gate electrode 2 . Then, P+ ions are implanted from above the channel protection film 5 to form contact layers 6a and 6b on the surface side of the semiconductor layer 4. Then,
Contact layer 6 is formed by photolithography and etching.
Contact layers 6a and 6b shown in FIG. 3B are patterned by removing unnecessary portions a and 6b.

Then, a source electrode 7 and a drain electrode 8 shown in FIG. 4 are patterned on top of the contact layers 6a and 6b patterned as described above to form a thin film transistor (hereinafter referred to as TFT).
(referred to as a Transistor) is formed. Then, an interlayer insulating film 9 is formed on the entire surface of the substrate 1 covering the TFT formed as described above, and a pixel electrode 10 is connected to the drain electrode 8 of the TFT through a contact hole 90 provided in the interlayer insulating film 9. are electrically connected.

0004

By the way, according to the above method, since the contact layers 6a, 6b are patterned after ion implantation into the semiconductor layer 4, the contact layers 6a, 6b after patterning are No contact layer is formed on the side surfaces of. For this reason, after pattern formation,
When the source electrode 7 and the drain electrode 8 are patterned on the contact layers 6a and 6b, respectively, the contact layer 6
There is a drawback that current leak occurs between a and 6b and the source electrode 7 and drain electrode 8, resulting in deterioration of TFT characteristics.

In addition, when patterning the channel protective film 5 on the semiconductor layer 4 and implanting P+ ions from above, the conventional method described above directly implants P+ ions, so that the channel protective film 5 is A small amount of impurity is also introduced into the material. Therefore, after performing ion implantation and patterning the contact layers 6a and 6b, when the source electrode 7 and drain electrode 8 are patterned on the contact layers 6a and 6b, respectively, the impurities slightly implanted into the channel protection film 5 pass through. Contact layers 6a and 6b
There is a drawback that current leak occurs between the source electrode 7 and the drain electrode 8, and the TFT characteristics deteriorate as described above.

The present invention eliminates the drawbacks of the prior art, and aims to provide a method for manufacturing an active matrix substrate that uses ion implantation to obtain good TFT characteristics.

[0007]

Means for Solving the Problems The method for manufacturing an active matrix substrate of the present invention includes: a gate electrode on an insulating substrate; a drain electrode at least partially overlapping the gate electrode with a gate insulating film and a semiconductor layer interposed therebetween; A method of manufacturing an active matrix substrate using a thin film transistor as a switching element having a source electrode that at least partially overlaps the gate electrode with a semiconductor layer in between includes the steps of patterning a channel protective film; The method includes a step of leaving a resist used for pattern formation and performing ion implantation from above the resist to form a contact layer, thereby achieving the above object.

Preferably, the contact layer is formed by performing ion implantation after patterning the semiconductor layer.

[0009]

[Operation] According to the above process, since the resist is left on the channel protective film and ions are implanted, impurities are not implanted onto the channel protective film. Therefore, even if the source and drain electrodes are patterned on the channel protective film,
No current leakage occurs between the source electrode and the drain electrode.

Furthermore, since the contact layer is formed by ion implantation after patterning the semiconductor layer, the side surfaces of the semiconductor layer are also doped with impurities. Therefore, even if the source and drain electrodes are patterned after ion implantation, current leakage occurring between the side surface of the contact layer into which ions have been implanted and the source and drain electrodes can be reduced.

[0011]

[Examples] Examples of the present invention will be described below.

FIG. 1 shows a method of manufacturing an active matrix substrate according to the present invention, and the active matrix substrate shown in FIG. 2 is manufactured through the steps shown below.

As shown in FIG. 1(a), Ta is first deposited to a thickness of 300 nm on a glass substrate 1 by sputtering. Next, from this state, a gate electrode 2 is patterned on the Ta layer using a photomask. Thereafter, a 300 nm thick gate insulating film 3 made of SiNx and a 30 nm thick amorphous silicon (hereinafter referred to as "a-Si") are deposited on the entire surface of the glass substrate 1 so as to cover the gate electrode 2 by plasma CVD. Layer 4 and S
A channel protective film 5 made of iNx and having a thickness of 200 nm is deposited in this order. Next, a resist 11 is applied on the uppermost channel protective film 5, and photolithography is performed to form an a-Si pattern as shown in FIG. 1(b).
Pattern layer 4 and channel protection film 5.

Next, from this state, photolithography is performed to form a pattern of the channel protective film 5 shown in FIG. 1(c). In this state, the resist 11 remains on the patterned channel protective film 5.

Next, as shown in FIG. 1C, P+ ions are implanted from above the channel protective film 5 in this state without removing the resist 11. As a result, Figure 1(d)
Contact layers 6a and 6b shown in are formed.

[0016] Next, a 300n
A Ti or Mo metal layer with a thickness of m is formed on the entire surface of the glass substrate 1, and this metal layer is patterned using a photomask to form the source electrode 7 and drain electrode 8 shown in FIG. . Then, on the entire surface of the glass substrate 1, a transparent electrode made of an indium tin oxide film (ITO) was formed with a thickness of 80 nm.
From this state, patterning is performed using a photomask to form the picture element electrode 10. In this way, the active matrix substrate of the present invention is produced.

According to the active matrix substrate produced in this manner, there is no current leakage (or (current leakage can be significantly reduced), and an active matrix substrate with good TFT characteristics can be obtained.

[0018]

According to the method for manufacturing an active matrix substrate of the present invention, current leakage between the contact layer and the source and drain electrodes can be significantly reduced due to the above-described steps. Therefore, the Ioff current of TFT characteristics is reduced. Therefore, an active matrix substrate with good TFT characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a method for manufacturing an active matrix substrate of the present invention.

FIG. 2 is a sectional view showing an active matrix substrate manufactured by the method of the present invention.

FIG. 3 is a process diagram showing a conventional manufacturing method.

FIG. 4 is a cross-sectional view showing an active matrix substrate manufactured by a conventional method.

[Explanation of symbols]

1 Glass substrate 2 Gate electrode 3 Gate insulating film 4 Semiconductor layer 5 Channel protective film 6a, 6b Contact layer 7 Source electrode 8 Drain electrode 9 Interlayer insulation film 10 Picture element electrode 11 Resist

Claims (2)

[Claims] 1. A gate electrode on an insulating substrate, a drain electrode that at least partially overlaps with the gate electrode through a gate insulating film and a semiconductor layer, and a drain electrode that overlaps at least partially with the gate electrode through the semiconductor layer. In a method of manufacturing an active matrix substrate using a thin film transistor having overlapping source electrodes as a switching element, a step of patterning a channel protective film, leaving a resist when patterning the channel protective film, and removing the upper part of the resist. A method of manufacturing an active matrix substrate, including a step of performing ion implantation to form a contact layer. 2. The method of manufacturing an active matrix substrate according to claim 1, wherein the contact layer is formed by performing ion implantation after patterning the semiconductor layer.