JPH04232923A - Production of electrode substrate for display device - Google Patents

Abstract

PURPOSE:To decrease the resistance of drain wiring and to reduce man-hour with reduction of masks by simultaneously forming wiring and electrodes from a transparent conductive film by photoetching with using one photomask and then depositing a metal film on drain wiring by plating. CONSTITUTION:Drain wiring 60, source electrode 7, drain electrode 6, and display electrode 8 are simultaneously formed from a transparent conductive film by photoetching with using one photomask. Then a metal film is deposited on the drain wiring 60 and drain electrode 6 by plating.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing thin film transistors suitable for active matrix liquid crystal display devices.

0002

2. Description of the Related Art In recent years, active matrix display devices have been developed in which thin film transistors (hereinafter referred to as TFTs) functioning as switching transistors are connected to each display electrode of a large number of pixels arranged in a matrix, and these TFTs are used as drive circuits. There is. This liquid crystal device is very light and thin, so it can be used as a portable device or as a wall-mounted device.
It is attracting attention as a thin display device that can replace the T.

FIG. 6(a) shows a plan view of each pixel of a TFT in a conventional active matrix display device.
FIG. 6(b) shows a sectional view taken along line BB' in FIG. 6(a).

As shown in FIG. 6(b), the TFT is formed on a transparent insulating substrate 1, and includes a gate electrode 2 forming part of a gate wiring 20, a gate insulating film 3 provided on the entire surface of the substrate,
An islanded semiconductor film 4, an impurity semiconductor film 4' forming an ohmic contact at each of the source and drain positions of the semiconductor film, and an islanded passivation insulating film 5.
, has a so-called inverted stagger type structure consisting of a stacked body of a source electrode 7 and a drain electrode 6, and a display electrode 8 is coupled to the source electrode 7, and the drain electrode 6 is coupled to a drain wiring 60 for supplying a display signal. There is.

[0005] When manufacturing this TFT, the following steps are performed: ■ formation of gate electrode 2, ■ formation of contact hole in gate insulating film 3, ■ formation of passivation insulating film 5 (island formation), ■ formation of island of semiconductor film 4, and ■ display electrode 8. At least 6 photomask steps are required to form 7 source electrodes and 6 drain electrodes.

[0006] As described above, in manufacturing TFTs, the long process is the biggest cause of reduced throughput. In particular, from the viewpoint of reducing manufacturing costs, there is a strong desire to improve throughput. In addition, the production of TFT is
The three steps of film formation, photolithography, and etching are repeated, but what determines the throughput during TFT manufacturing is the photolithography process using a mask aligner that requires highly accurate positioning.

[0007]

Therefore, reducing the number of photomasks used in the TFT manufacturing process improves throughput and reduces manufacturing costs. With the current equipment capacity, for example, if a TFT that used to be manufactured using 6 photomasks is manufactured using 5 photomasks,
It is no exaggeration to say that the throughput will be increased by 6/5 times. Therefore, it is necessary to reduce the number of photomasks used.

[0008]

[Means for Solving the Problems] A method of manufacturing an electrode substrate for a display device according to the present invention includes a plurality of drain wirings and a plurality of gate wirings on a transparent insulating substrate. A method for manufacturing a display device comprising a transistor disposed at each intersection with a gate wiring, and a display electrode coupled to the transistor, wherein the drain wiring and the transistor are configured and locally connected to the drain wiring. After simultaneously forming a drain electrode, a source electrode constituting the transistor, and a display electrode connected to the source electrode using a transparent conductive film, a metal film is deposited by plating on the drain wiring and the drain electrode. It is something.

[0009] Further, the metal film may be a Cu single layer film or a Cu single layer film.
It consists of a multilayer film including at least one layer of.

[0010]Furthermore, on the transparent insulating substrate, a gate wiring,
After sequentially depositing a first insulating film, a semiconductor film, and a second insulating film, a drain wiring, a drain electrode locally connected to the drain wiring, and a drain electrode located opposite to the drain electrode were arranged on the second insulating film. In a method for manufacturing a display device in which a source electrode and a display electrode connected to the source electrode are simultaneously formed, a region of the second insulating film overlaps at least three peripheral sides of the drain electrode that are not in contact with the drain wiring. It is something.

Furthermore, after sequentially depositing a gate wiring, a first insulating film, a semiconductor film, and a second insulating film on a light-transmitting insulating substrate, a drain wiring is deposited on the second insulating film, and a drain wiring is locally deposited on the drain wiring. In a method for manufacturing a display device in which a connected drain electrode, a source electrode disposed opposite to the drain electrode, and a display electrode connected to the source electrode are simultaneously formed, a region of the second insulating film is connected to the drain electrode. The source electrode of the wiring at least overlaps the opposing sides.

0012

[Operation] According to the present invention, a drain wiring, a drain electrode, a source electrode, and a display electrode are simultaneously formed using a transparent conductive film, and then a metal film such as Cu is plated on the drain wiring. It is possible to lower the resistance of wiring made of Therefore, by making it possible to reduce the wiring resistance, simultaneous formation of the electrode and the wiring can be realized for the first time, and the number of man-hours can be reduced.

Furthermore, even if the dimensions of the drain wiring are exceeded due to plating, the channel length and channel width will not change by forming the second insulating film before plating.

[0014]

[Example] FIG. 1(a) shows a plan view of a pixel unit of a TFT array of an active matrix liquid crystal display device obtained by the manufacturing method of the present invention, and FIG.
A cross-sectional view taken along line BB' is shown. Further, cross-sectional views of each manufacturing process along line BB' (TFT region) in FIG. 1(a) are shown in FIGS. 2(i) to 2(v). The manufacturing method of the present invention will be explained below with reference to FIG.

First step [FIG. 2(i)] Mo, Cr, W, Ti, Ta, Al are deposited on a transparent insulating substrate made of glass or the like.
A gate wiring 20 locally provided with a gate electrode 2 made of a metal such as the like is formed, and the gate electrode 2 is formed.

Second step [FIG. 2(ii)] First insulating film 3 (
A gate insulating film), a semiconductor film 4, and a second insulating film (passivation insulating film) 5 are successively deposited by plasma CVD or the like, and then the second insulating film 5 is etched to form islands.

Third step [FIG. 2(iii)] Plasma CV
After depositing the impurity semiconductor film 4' in step D, the semiconductor film 4
This impurity semiconductor film 4' is then etched to form islands.

Fourth step [FIG. 2(iv)] ITO, In2
A transparent conductive film made of O3, SnO2, ZnO, Cd2SnO4, etc. is deposited, and the drain electrode 6, source electrode 7, display electrode 8, and drain wiring 60 are simultaneously formed using the transparent conductive film. Thereafter, the impurity semiconductor film 4' in the channel portion is removed by etching.

Fifth step [FIG. 2(v)] Drain wiring 6
A metal film 10 is deposited by plating on the drain electrode 6 locally connected to the electrode 0 and the drain wiring 60. The materials for forming the metal film 10 to be plated include Au, Cu, and Ni.
, Pd, Ag, Pt, In, Ru, Rh, Cr, Sn,
Metals such as Pb, Sn-Pb (solder), Zn, Co, and Fe can be used.

Among these metals, Cu is the most excellent in terms of low resistance and cost. however,
The adhesion of the Cu film to the ITO film is poor, and as shown in FIG. Improves sex. Materials for forming the intervening metal film 12 include Ni, In, Sn, Pb, and S.
Metals such as n-Pb (solder), Zn, and Co are excellent. Further, since the Cu film is easily oxidized, another metal film for preventing oxidation, such as a metal film such as Au, Pt, Pd, or Cr, may be deposited on the plated Cu film (not shown). The metal film deposited by plating in this manner may be a single layer film or a multilayer film. In addition, the metal film deposited on the transparent conductive film by plating is Cu.
The material is not limited to the above, and any material may be used as long as it can be deposited on the transparent conductive film by plating and lowers the wiring resistance.

[0021] Here, the plating method will be explained. As a plating method, an electroless plating method can also be applied, but in that case, it is necessary to coat the area where the metal film is not deposited with a resist. That is, when electroless plating is applied, one mask step is added, so electrolytic plating is suitable as the plating method. Furthermore, when electrolytic plating is applied, if the impurity semiconductor film 4' exists in the channel part, the metal film 10 will also be deposited on the transparent conductive films of the source electrode 7 and the display electrode 8. ' must be removed by etching in advance.

When a metal film is deposited by a plating method, the dimensions of the plated metal film pattern become larger than the transparent conductive film pattern, and as a result, the dimensions of the drain electrode 6 change, and the channel width and channel length may change. . Therefore,
By forming the passivation film 5 on the semiconductor film 4 in advance, the channel width and channel length of the TFT can be prevented from changing due to such dimensional changes of the drain electrode 6. For example, if the shape of the passivation film 5 is as shown in FIG. Unaffected by change.

FIG. 4(a) shows a TFT according to another embodiment of the present invention.
A plan view of the section is shown in FIG. 4(b) along line BB' in FIG. 4(a).
A cross-sectional view of the line is shown.

In the TFT pattern shown in FIG. 4(b), the channel width and channel length are determined by the dimensions of the passivation film 5, and therefore are not affected by dimensional changes due to plating of the drain electrode 6. However, the shape of the passivation film 5 that determines the channel width and channel length as shown in FIG. 4 may be only on the drain electrode 6 side, and the shape of the passivation film 5 on the source electrode 7 side may be the shape shown in FIG. Furthermore, in the case of the shape shown in FIG. 5, the channel length is determined by the shape of the passivation film 5, while the channel width is determined by the shape of the gate electrode 2.
, source electrode 7, passivation film 5 and semiconductor film 4
It is determined by the shape of the drain electrode 6, and is not affected by dimensional changes of the drain electrode 6.

In this way, according to this embodiment, the source electrode 7, drain electrode 6, drain wiring 60, and display electrode 8, which were conventionally formed using two photomasks, can be formed using one photomask.
It can be formed by a mask step (fourth step) and a plating step that does not require a mask (fifth step).

[0026]

[Effects of the Invention] As is clear from the above description, according to the manufacturing method of the present invention, the drain wiring, drain electrode, source electrode, and display electrode are formed at the same time, so the number of photomask steps can be reduced by one step. Furthermore, compared to dry film forming methods such as sputtering and vapor deposition, wet film forming methods (
Since the metal film for forming the drain wiring is deposited by a plating method, the manufacturing cost of the TFT can be reduced.

Furthermore, even if the pattern size of the metal film deposited by plating becomes larger than the pattern of the transparent conductive film, the channel length and channel width of the TFT can be changed by forming a passivation film in advance. This prevents the characteristics from being affected and enables stable display.

[Brief explanation of the drawing]

FIG. 1 (a) shows T of a display device obtained by the present invention.
FIG. 3B is a plan view of the FT section, and FIG. 3B is a cross-sectional view of the TFT section of the display device obtained by the present invention.

FIG. 2 is a cross-sectional view of each manufacturing process taken along line BB' in FIG. 1(a).

FIG. 3 is a sectional view of a TFT section according to another embodiment of the present invention.

4(a) is a plan view of a TFT section according to still another embodiment of the present invention, and FIG. 4(b) is a sectional view taken along line BB' in FIG. 4(a).

FIG. 5 is a plan view of a TFT section according to yet another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional display device.

[Explanation of symbols]

1 Translucent insulating substrate 2 Gate electrode 3 Gate insulating film 4 Semiconductor film 4’ Impurity semiconductor film 5 Passivation insulation film 6 Drain electrode 7 Source electrode 8 Display electrode 10 Metal film 12 Metal film 11 Cu film 20 Gate wiring 60 Drain wiring

Claims (4)

[Claims] 1. A plurality of drain wirings and a plurality of gate wirings are provided on a transparent insulating substrate, a transistor is arranged at each intersection of the plurality of drain wirings and the plurality of gate wirings, and the transistor is coupled to the transistor. In the method of manufacturing a display device comprising a display electrode, the drain wiring, a drain electrode forming the transistor and locally connected to the drain wiring, a source electrode forming the transistor, and the source electrode A method for manufacturing a display device, comprising simultaneously forming connected display electrodes using a transparent conductive film, and then depositing a metal film on the drain wiring and the drain electrode by a plating method. 2. The method of manufacturing a display device according to claim 1, wherein the metal film is a Cu single layer film or a multilayer film containing at least one layer of Cu. [Claim 3] A gate wiring, a first
After sequentially depositing an insulating film, a semiconductor film, and a second insulating film, the second insulating film is deposited.
A display device in which a drain wiring, a drain electrode locally connected to the drain wiring, a source electrode placed opposite to the drain electrode, and a display electrode connected to the source electrode are simultaneously formed on an insulating film. In the manufacturing method of
2. The method of manufacturing a display device according to claim 1, wherein the region of the second insulating film overlaps at least three peripheral sides of the drain electrode that are not in contact with the drain wiring. 4. A gate wiring, a first
After sequentially depositing an insulating film, a semiconductor film, and a second insulating film, the second insulating film is deposited.
A display device in which a drain wiring, a drain electrode locally connected to the drain wiring, a source electrode placed opposite to the drain electrode, and a display electrode connected to the source electrode are simultaneously formed on an insulating film. In the manufacturing method of
2. The method of manufacturing a display device according to claim 1, wherein the region of the second insulating film overlaps at least a side of the drain wiring that faces the source electrode.