JPH04247433A - Production of active matrix substrate - Google Patents

Abstract

PURPOSE:To improve TFT characteristics and to improve production efficiency by decreasing the current leakage between contact and source electrodes and drain electrodes of the active matrix substrate. CONSTITUTION:After a-Si layers 4 are patterned and formed, P<+> ions are implanted therein to form contact layers 6a, 6b, by which the impurity is implanted into the side faces of the a-Si layers 4 as well. A resist 11 is made to remain on a channel protective film 5 and is used as an implantation mask 11. The ions are implanted from the upper part of the injection mask 11 so that the impurity is not implanted to the channel protective film. Further, the resist 11 is lifted off and source electrodes and drain electrodes are formed, by which the need for a patterning process is eliminated.

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. 4 shows the process of forming a contact layer in a conventional method of manufacturing an active matrix substrate by ion implantation. As shown in FIG. Then, a gate insulating film 3 is formed on the gate electrode 2. Next, a semiconductor layer 4 is formed on the gate insulating film 3, and a channel protection insulating film 5 is patterned thereon. Thereafter, P+ ions are implanted from above the channel protection insulating film 5, thereby forming contact layers 6a and 6b. Next, as shown in FIG. 4(b), contact layers 6a and 6b are patterned in contact with the semiconductor layer 4.

Next, a source electrode 7 and a drain electrode 8 are respectively formed on the contact layers 6a and 6b patterned in this way, as shown in FIG. 4(c). As a result, thin film transistors (hereinafter referred to as "T"
A pixel electrode 9 is electrically connected to the drain electrode 7.

0004

By the way, in the case of forming the contact layers 6a and 6b using the above-described procedure, the contact layers 6a and 6b are patterned after P+ ions are implanted into the semiconductor layer 4. Therefore, no contact layer is formed on the side surfaces of the contact layers 6a and 6b after pattern formation.

Therefore, after that, contact layers 6a, 6
When the source electrode 7 and the drain electrode 8 are patterned on the TFT
The disadvantage is that the characteristics deteriorate.

Furthermore, as shown in FIG. 4B, when a channel protection film 5 is patterned on the semiconductor layer 4 and P+ ions are implanted from above, a step of directly implanting P+ ions is performed. Therefore, a small amount of impurity 6c is also implanted into the upper layer of the channel protective film 5. For this reason, if the contact layers 6a and 6b are patterned after ion implantation, and then the source electrode 7 and the drain electrode 8 are patterned on the contact layers 6a and 6b, impurities slightly implanted onto the channel protective film 5 are removed. There is also a drawback that current leakage occurs between the contact layers 6a and 6b and the source electrode 7 and drain electrode 8 through the contact layer 6c, resulting in deterioration of TFT characteristics.

[0007] In order to solve these drawbacks, P+ ions may be implanted with the resist remaining on the channel protective film 5. However, this method poses a new problem of complicating the manufacturing process, and currently no effective method that solves this problem has been realized.

The present invention solves the drawbacks of the prior art, and in addition to simplifying the manufacturing process,
An object of the present invention is to provide a method of manufacturing an active matrix substrate that uses ion implantation to obtain good TFT characteristics.

[0009]

[Means for solving the problem] The method for manufacturing an active matrix substrate of the present invention includes a gate electrode on an insulating substrate,
a drain electrode that at least partially overlaps with the gate electrode via a gate insulating film, a semiconductor layer, and a contact layer;
In a method for manufacturing an active matrix substrate using a thin film transistor as a switching element having the gate electrode and a source electrode that at least partially overlaps via the semiconductor layer, a resist is patterned, and the pattern is formed from above. The method comprises a first step of performing ion implantation into the semiconductor layer to form the contact layer, and a second step of forming the drain electrode and the source electrode by lift-off using the resist. The above objective is achieved.

Preferably, a resist is patterned on the channel protective film, and ions are implanted from above.

[0011]

[Operation] As described above, when a contact layer is formed by ion implantation after patterning a semiconductor layer, impurities are also implanted into the side surfaces of the semiconductor layer. Therefore,
If the source and drain electrodes are patterned after ion implantation, current leakage between the source and drain electrodes and the side surfaces of the contact layer can be significantly reduced.

Furthermore, if the resist is left on the channel protective film and the ions are implanted from above, impurities are not implanted into the channel protective film. Therefore, current leakage does not occur between the contact layer and the source electrode and drain electrode formed later through impurities.

Furthermore, since the source and drain electrodes are formed by lifting off the resist, there is no need to perform a patterning process. Therefore, the number of steps can be reduced, and a simplified and efficient manufacturing process can be enjoyed.

[0014]

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

FIGS. 1 and 2 show an embodiment of the method of the present invention, in which FIGS. 2(a) and 2(b) show plane views during the manufacturing process of an active matrix substrate produced by the method of the present invention. Figure 2(a) shows the change in structure.
The cross-sectional structure shown along line X-X in FIG. )
The cross-sectional structure shown by the Y-Y line shows the cross-sectional structure of the active matrix substrate in the manufacturing process shown in FIG. 1(g). The details will be explained below with reference to FIGS. 1 and 2.

First, as shown in FIG. 1(a), 200 nm of Ta is deposited on the surface of a glass substrate 1 by sputtering.
Deposit at a thickness of m to 400 nm. Next, a gate electrode 2 is patterned on the Ta layer using a photomask. Next, the glass substrate 1 is placed so as to cover the gate electrode 2.
A gate insulating film 3 made of SiNx with a thickness of 200 nm to 500 nm and a thickness of 2
Amorphous silicon of 0 nm to 50 nm (hereinafter referred to as “a-
layer 4 (referred to as ``Si'') and a thickness 100 consisting of layer 4 and SiNx.
A channel protective film 5 with a thickness of nm to 300 nm is deposited. Next, a resist 10 is coated on the channel protective film 5, and photolithography is performed on the resist 10 in a pattern of the a-Si layer 4 to form the a-Si layer 4 as shown in FIG. 1(b).
Then, the channel protective film 5 is patterned.

Next, photolithography is performed to form the channel protective film 5 shown in FIG. 1(c) and FIG. 2(a).
form a pattern. Then, as shown in FIG. 1C, the resist 11 patterned by the photolithography is used as an implantation mask 11 without peeling, and the P+
Ions are implanted to form contact layers 6a and 6b (FIG. 1(d)).

Next, as shown in FIG. 1(e), Ti is deposited to a thickness of 200 nm to 400 nm by sputtering.
Alternatively, a metal layer 12 of Mo is formed on the entire surface of the glass substrate 1 so as to cover the contact layers 6a, 6b, etc. Then, this metal layer 12 is lifted off using the implantation mask 11 to form the source electrode 7 and drain electrode 8 shown in FIG. 1(f).

Next, a transparent electrode made of indium tin oxide (ITO) is deposited on the entire surface of the glass substrate 1 to a thickness of 50 nm to 50 nm.
It is deposited to a thickness of 100 nm, and further patterned using a photomask to form the picture element electrode 9. As a result, an active matrix substrate having the structure shown in FIG. 1(g) and FIG. 2(b) is created.

As mentioned above, the channel protective film 5 and a
-If the Si layer 4 is patterned and then P+ ions are implanted to form the contact layers 6a and 6b,
Since impurities are surely implanted into the side surfaces of contact layers 6a and 6b, source electrode 7 and drain electrode 8 and contact layers 6a and 6, which are patterned after ion implantation, are
It is possible to significantly reduce current leakage between the

In addition, if P+ ions are implanted into the channel protection film 5 from above the implantation mask 11 as described above, impurities are not implanted into the top of the channel protection film 5. Therefore, contact layers 6a and 6 can be formed through impurities.
No current leakage occurs between b and source electrode 7 and drain electrode 8.

Furthermore, since the source electrode 7 and drain electrode 8 are formed by lifting off the implantation mask 11, there is no need to perform a patterning process. Therefore, the number of steps and manufacturing time can be reduced, so a simplified and efficient manufacturing process can be enjoyed.

FIG. 3 shows another embodiment of the present invention,
This example shows a method of manufacturing an active matrix substrate without a channel protective film. That is, Figure 3
As shown in (a), Ta is first deposited to a thickness of 200 nm to 400 nm on the surface of a glass substrate 1 by a sputtering method in the same manner as in FIG. 1 (a) of the above embodiment.
Gate electrode 2 is patterned using a photomask. Next, the glass substrate 1 is placed so as to cover the gate electrode 2.
A gate insulating film 3 made of SiNx with a thickness of 200 nm to 500 nm and an a-Si layer 4 with a thickness of 20 nm to 50 nm are deposited on the entire surface by plasma CVD, and then
A resist 10 is applied on the a-Si layer 4 to form the a-Si layer 4.
Photolithography was performed using the pattern shown in Figure 3(b).
The a-Si layer 4 is patterned as shown in FIG.

Next, as shown in FIG. 3(b), photolithography is performed to pattern the implantation mask 11. Then, as shown in FIG. 3C, P+ ions are implanted into the a-Si layer 4 from above the implantation mask 11 to form contact layers 6a and 6b (FIG. 3D).

Next, as shown in FIG. 3(e), a T layer with a thickness of 200 nm to 400 nm is formed by sputtering.
The metal layer 12 of i or Mo is connected to the contact layers 6a, 6b.
It is formed on the entire surface of the glass substrate 1 so as to cover the other parts. Next, this metal layer 12 is lifted off using the implantation mask 11, thereby forming a source electrode 7 and a drain electrode 8 (FIG. 3(f)). Then, a transparent electrode made of indium tin oxide (ITO) is deposited on the entire surface of the glass substrate 1 to a thickness of 50 nm to 100 nm, and further patterned using a photomask to form the picture element electrode 9. As a result, an active matrix substrate having the structure shown in FIG. 3(g) is created.

This embodiment also has the same effect as the above embodiment, that is, the impurities are reliably implanted also into the side surfaces of the contact layers 6a and 6b, so that the source electrode 7 and drain electrode 8 patterned after ion implantation are It is possible to significantly reduce current leakage occurring between the contact layer 6a and the contact layer 6a and 6b, to reduce the number of steps and manufacturing time, and to enjoy a simplified and efficient manufacturing process.

[0027]

According to the above-described method of the present invention, current leakage between the contact layer and the source and drain electrodes can be significantly reduced, so that the Ioff current of TFT characteristics is reduced. Therefore, an active matrix substrate with excellent TFT characteristics can be realized. Moreover, since the resist is lifted off to form the source and drain electrodes,
No patterning process is required. Therefore, the number of steps and manufacturing time can be reduced, so that an efficient manufacturing process can be enjoyed.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the manufacturing process of the method of the present invention.

FIG. 2 is a drawing showing changes in the planar structure during the manufacturing process of an active matrix substrate produced by the method of the present invention.

FIG. 3 is a process diagram showing another embodiment of the method of the present invention.

FIG. 4 is a process diagram showing a conventional method of manufacturing an active matrix substrate by ion implantation.

[Explanation of symbols]

1 Glass substrate 2 Gate electrode 3 Gate insulating film 4 Semiconductor layer (a-Si layer) 5 Channel protective film 6a, 6b Contact layer 7 Source electrode 8 Drain electrode 9 Picture element electrode 10 Resist 11 Resist (injection mask)

Claims (2)

[Claims] 1. A gate electrode on an insulating substrate, a drain electrode that at least partially overlaps with the gate electrode via a gate insulating film, a semiconductor layer, and a contact layer; In a method for manufacturing an active matrix substrate using a thin film transistor having a partially overlapping source electrode as a switching element,
A first step of patterning a resist and implanting ions into the patterned semiconductor layer from above to form the contact layer; and a lift-off using the resist to form the drain electrode and the source electrode. and a second step of forming an active matrix substrate. 2. The method of manufacturing an active matrix substrate according to claim 1, wherein a resist is patterned on the channel protective film, and ions are implanted from above.