JPH0568708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a display electrode array for an active matrix display device in which the display electrode array is constructed using thin film transistors (TFTs) as switch elements.

[Technical background of the invention and its problems] Recently, liquid crystals and electroluminescence (EL)
As for display devices using the BACKGROUND ART, large-capacity, high-density active matrix type display devices aimed at television displays, graphic displays, etc. are being actively developed and put into practical use. In such display devices, semiconductor switches are used as means for driving and controlling each pixel so that high contrast display without crosstalk can be achieved. These semiconductor switches include MOSFETs formed on single-crystal Si substrates,
Recently, TFTs formed on transparent insulating substrates have been used because they enable transmissive display and are easy to increase in area.

FIG. 2 is an equivalent circuit of a liquid crystal display device using a display electrode array equipped with TFTs. Xi(i=1,
2,..., m) are column selection lines that are normally used as data lines, Yj (j=1, 2,..., n) are row selection lines that are normally used as address lines, and these column selection lines Xi and row selection lines TFT-1 at each intersection of line Yi
1 is provided. The drains of the TFT-11 are connected to column selection lines Xi for each column, and the gates are connected to selection lines Yj for each row. Display pixel electrodes 12 are connected to the sources of the TFT-11, and a liquid crystal 13 is sandwiched between the display pixel electrodes 12 and the counter electrode 14.

FIG. 3 is a diagram showing a schematic cross-sectional structure of such a liquid crystal display device. TFT on transparent insulating substrate 21
(omitted from the figure) and display pixel electrodes 12 made of a transparent conductive film are arranged, and a liquid crystal 13 is sandwiched between this and a transparent insulating substrate 22 on which a counter electrode 14 made of a transparent conductive film is formed on the entire surface. It becomes a structure.
23 is a spacer and a sealing part.

A more specific example of the structure of the substrate on which the display pixel electrodes 12 of FIG. 3 are arranged, that is, the so-called display electrode array, is shown in FIGS. 4 a to 4 c for one pixel portion. FIG. 4a is a plan view, and FIGS. 4b and 4c are cross sections A-A' and B-B' in FIG. 4a, respectively. To explain this according to the structural steps, a transparent conductive film such as ITO is formed on the transparent insulating substrate 21,
This is patterned to form a column selection line Xi, a drain electrode 31 integrated therewith, a display pixel electrode 12, and a source electrode 32 integrated therewith. Next, a semiconductor thin film 33 made of amorphous Si or the like is formed for each pixel so as to straddle the drain electrode 31 and the source electrode 32. And as a gate insulating film
After depositing the SiO ₂ film 34 over the entire surface, an Al film or the like is deposited and patterned to form the row selection line Yj and the gate electrode 35 integrated therewith. Thereafter, a SiO ₂ film 36 as a protective film is deposited over the entire surface, and the SiO ₂ films 34 and 36 on the surface of the display pixel electrode 12 are etched to complete the display electrode array.

The operation of such an active matrix type liquid crystal display device is performed as follows. Row selection line Yj
is sequentially scanned and driven by the address signal, and the TFT
-11 are sequentially brought into conduction for T _F /n periods for each row. On the other hand, in synchronization with the scanning of the row selection line Yj, for example, m parallel image signal voltages are supplied to the column selection line Xi. As a result, the signal voltage is sequentially guided to the display electrodes 12 row by row, and the liquid crystal 13 sandwiched between the counter electrode 14 is excited and an image is displayed.

By the way, in the conventional display electrode array shown in FIG. 4, when manufacturing it, it is necessary to form one or more layers of a conductive film, a semiconductor film, and an insulating film, and pattern each of them into a predetermined shape. It's complicated. Further, depending on the patterning of each layer, a step is generated on the surface thereof, and there is a problem that reliability and yield are reduced due to step breaks in electrode wiring, etc. For example, as is clear from FIG.
are integrally connected. Therefore, if a disconnection occurs due to this step, it will result in a pixel defect.

[Object of the Invention] In view of the above points, the present invention aims to simplify the manufacturing process of display electrode arrays equipped with TFTs, and to improve reliability and yield by preventing disconnection of electrode wiring. An object of the present invention is to provide a method for manufacturing a display electrode array for a matrix type display device.

[Summary of the Invention] The present invention provides a method for manufacturing a display electrode array for an active matrix display device in which a plurality of display pixel electrodes selectively driven by a plurality of thin film transistors are arranged in a matrix. A conductive layer is deposited, and the first conductive layer forms a plurality of column selection lines, a drain electrode integrated with each column selection line, a display pixel electrode arranged at each pixel position, and a display pixel electrode integrated therewith. a step of forming a source electrode, and a step of successively depositing a semiconductor thin film, a gate insulating film, and a second conductive layer on the substrate;
A step of forming a plurality of row selection lines and a gate electrode integral therewith with the second conductive layer, successively etching the gate insulating film and the semiconductor thin film, and depositing a protective film on the substrate. an active matrix, comprising the step of selectively removing the protective film in a peripheral area including a take-out area for electrically connecting at least each column selection line and each row selection line to the outside of the display electrode array; This is a method for manufacturing a display electrode array for a Tux type display device.

[Examples of the invention] Examples of the invention will be described below. Figure 1 a~
f describes one embodiment of the present invention. The left side shows the TFT array section, and the right side shows the signal line pad section. First, as shown in FIG. 1a, ITO 41 with a thickness of 1000 Å and phosphorus-doped amorphous silicon 42 with a thickness of 500 Å are laminated on a glass substrate 40. Next, a predetermined pattern is formed using a mask commonly used in the IC manufacturing process or in a lithography process, and the phosphorus-doped amorphous silicon 42 is etched using chemical dry etching, followed by hydrochloric acid containing nitric acid.
By etching the ITO 41, patterns for the source/drain portions of the TFT, signal lines, and pixel electrodes are obtained (FIG. 1b). Next, 4000 Å of intrinsic amorphous silicon 43, 4000 Å of silicon nitride 44, and aluminum 45 are sequentially deposited (FIG. 1c). Lithography is performed using the second mask to form a predetermined pattern, and aluminum 4 is etched using an aluminum etching solution.
Etch 5. Next, the silicon nitride film 44 and the intrinsic amorphous silicon 43 are etched by chemical dry etching to form a TFT.
46 (Fig. 1d). In this step, the external extraction portion of the column selection line appears on the surface (right side of FIG. 1d). At this stage, the display electrode array is almost completed, and the process is completed with two masks. If a protective film is required, then a protective film 47 of 1 μm silicon nitride is deposited (FIG. 1e). Lithography is performed using a third mask to form a pattern excluding the protective film 47 of the row and column selection line extraction portions 48 and the pixel portion 49, and the protective film 47 is etched by chemical dry etching. At the same time, unnecessary phosphorus-doped amorphous silicon 42 on ITO 41 is also removed (FIG. 1f). Through the above steps, the display electrode array including the protective film is completed. In FIG. 1f, the glass substrate 40 is a transparent insulating substrate.
ITO41 and phosphorus-doped amorphous silicon 42
serves as a first conductive layer and forms a drain electrode 50, a source electrode 51, a pixel portion (display pixel electrode) 12, and a column selection extraction portion (column selection line) 48. Intrinsic amorphous silicon 43 becomes a semiconductor thin film, silicon nitride 44 becomes a gate insulating film, aluminum layer 45 becomes a second conductive line,
A gate electrode and a row selection line extraction portion (row selection line) are formed.

According to this embodiment, the TFT array requires only three masks, including the patterning of the protective film, and the manufacturing process is simpler than that of the conventional method.

In this embodiment, the aluminum layer 45, silicon nitride 44, and intrinsic amorphous silicon 43 are etched while the resist is still attached.
After the resist is removed, the silicon nitride 44 and the thin phosphorescent amorphous silicon 43 may be etched by chemical etching.

In this example, the external part of the column selection line is formed of ITO, so it is difficult to connect it to the outside with gold or aluminum wire bonding, but it is difficult to connect it to the outside with gold or aluminum wire bonding. External connections can be made without any problems by using commonly used connection methods.

In the present invention, the "peripheral area including the take-out area" includes the take-out parts of each row selection line and each column selection line, as well as all the take-out parts that require grounding wires and other electrical connections to the outside. But that's fine.

The above discussion has centered on TFTs using amorphous Si, but as a semiconductor layer, poly-Si,
Compound semiconductors such as CdSe and CdS may also be used. Also,
Although the case where silicon nitride is used as the gate insulating layer has been described, it may be an inorganic insulating film such as silicon oxide or silicon oxynitride, an organic insulating film such as polyimide, or a multilayer structure.

Although the first conductive layer has been described as a laminated layer of ITO and phosphorus-doped amorphous silicon, it may be only ITO, or may be a three-layer laminated layer of ITO, molybdenum, and phosphorus-doped amorphous silicon. Additionally, if transparency is not required, Al,
A metal layer such as Cr or Mo may also be used. The gate electrode may be made of polysilicon, Cr, Mo, aluminum silicon, molybdenum silicide, etc. in addition to Al. Various methods such as plasma CVD, normal pressure/low pressure CVD, vapor deposition method, sputtering method, molecular beam method, spin-on method, etc. can be used to manufacture each of the above layers.

[Effects of the Invention] According to the present invention, the process can be simplified compared to the conventional case where patterning is performed for each layer. Specifically, a TFT array can be manufactured using three masks including the formation of a protective layer.

Further, according to the present invention, since the row selection line and the gate electrode are formed by the second layer conductive film without any difference in level,
Even when the semiconductor thin film is relatively thick, there is no discontinuity, improving reliability and yield. Furthermore, there is no need to electrically connect conductive layers that are produced in separate steps, improving reliability and yield.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining the manufacturing process of one pixel part of a display electrode array and a column electrode extraction part in an embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of an active matrix type liquid crystal display device. Third
The figure is a schematic sectional view of the structure, and FIGS. 4a-4c are a plan view and AA' and BB' sectional views showing the structure of one pixel portion of the display electrode array. 40...Glass substrate, 41...ITO, 42...
Phosphorus-doped amorphous silicon, 43... Intrinsic amorphous silicon, 44... Silicon nitride, 45... Aluminum layer, 47... Protective film.

Claims (1)

[Claims] 1. In a method of manufacturing a display electrode array for an active matrix display device in which a plurality of display pixel electrodes selectively driven by a plurality of thin film transistors are arranged in a matrix, a first pixel electrode is formed on a substrate.
A conductive layer is deposited, and the first conductive layer forms a plurality of column selection lines, a drain electrode integrated with each column selection line, a display pixel electrode arranged at each pixel position, and a display pixel electrode integrated therewith. a step of forming a source electrode, a step of successively depositing a semiconductor thin film, a gate insulating film, and a second conductive layer on the substrate;
A step of forming a plurality of row selection lines and a gate electrode integrated with the conductive layer, successively etching the gate insulating film and the semiconductor thin film, depositing a protective film on the substrate, and etching at least each row selection line. An active matrix type display device comprising a step of selectively removing the protective film in a peripheral area including a take-out area for electrically connecting a column selection line and each row selection line to the outside of the display electrode array. A method for manufacturing a display electrode array for use in a computer.