JPH03192730A - Manufacture of thin film transistor array of active matrix diaplay - Google Patents

Abstract

PURPOSE:To enable an active matrix display in high opening ratio and high precision to be manufactured by a method wherein semiconductor films and a transparent conductive film are patterned by selfmatching process using the rear exposure while a drain wiring is liftoff formed using resist for the display electrode patterning process. CONSTITUTION:Multiple gate wirings 20 comprising an opaque metal are formed on a transparent substrate 1; after laminately forming a phototransmitting gate insulating film 3, transparent conductive films S4, S5 are formed into films; resist R1 in inverse pattern of the gate wirings 20 are left by the rear exposure using the gate wirings 20 as masks on the surfaces of the transparent films S4, S5 coated with the resist R1. Next, the transparent conductive films S4, S5 are patterned to be isolated along the gate wirings 20 using the remaining resist R1 as a mask to be coated with resist R2 repeatedly; resist 3 on the positions excluding the drain wiring position is left by exposure process; a conductive transparent film C6 is patterned to be isolated along the drain wiring using the resist R3 as a mask. Through these procedures, a semiconductor film 4 and the transparent conductive film C6 can be formed in offset state with high precision respectively on the gate electrode 2 and the gate wirings 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method of manufacturing a thin film transistor array for an active matrix display device.

(b) Conventional technology In recent years, active matrix display devices have been developed in which thin film transistors (hereinafter referred to as TPTs) functioning as switching transistors are connected to each display electrode of a large number of pixels arranged in a matrix, and these TPTs are used as drive circuits. ing. This device supplies pixel information to each display electrode via TPT, and optical changes occur in the liquid crystal layer, EL layer, or EC layer provided on the display electrode by electric field, current, or power according to this pixel information. [Japanese Patent Publication No. 62-6674].

In particular, active matrix liquid crystal display devices using the above-mentioned liquid crystal layer are currently attracting attention as displays for portable TVs.

FIG. 4(a) shows a plan view of each pixel of a TPT array in a conventional active matrix liquid crystal display device.
FIG. 5B shows a cross-sectional view taken along line A-A of the TFT position.

These TPTs in the same figure are attached to one insulating substrate 1 of the liquid crystal cell.
Ohmic contacts are formed on the gate electrode 2 forming a part of the gate line 20, the gate insulating film 3 provided on the entire surface of the substrate, the localized semiconductor film 4, and the source and drain positions of the semiconductor film 4. It has a so-called inverted stagger type structure consisting of a stacked structure of impurity semiconductor films 5, 5, a source electrode 7, and a drain electrode 8, and a display electrode 6 for each pixel is connected to this source electrode 7.

TP of such a conventional active matrix display device
The method for manufacturing the T-array will be outlined below in order of steps.

(1) Step of forming a wiring metal film on the insulating substrate 1 and forming the gate line 20 including the gate electrode 2 using a photomask and photoresist.

(2) Using a P-CVDI device etc., the gate insulating film 3,
Step of sequentially forming a non-single crystal semiconductor film 4 and a non-single crystal impurity semiconductor film 5.

(3) Step 7 of etching the semiconductor film 4 and the impurity semiconductor film 5 using an otmask and a photoresist.

(4) Step of forming a transparent conductive film and forming display electrodes 6 using an otomask and a photoresist.

(5) A step of forming a metal film for wiring and forming a drain line 80 including a source electrode 7 and a drain electrode 8 using a 7-oto mask and a photoresist.

(6) Etching the impurity semiconductor film 5 at the channel position between the picture electrodes 7 and 8.

(c) Problems to be Solved by the Invention According to the method of manufacturing a TPT array for an active matrix display device as described above, the processing accuracy of the TPT pattern is determined by the capabilities of the photomask and the exposure device.

Generally, the pitch error of the current 7 otomasks is ±1μm,
Since the alignment error of the exposure device is ±1 μm, according to the conventional manufacturing method described above, the alignment error is ±2 μm, that is, 0 to 0.
A shift in the pattern position of 4 μm occurred, and a pattern design with sufficient margin to account for this position shift was required.

Therefore, when manufacturing a display device with a high pixel density, such as an ultra-high-definition liquid crystal display device compatible with high-definition television, with a pixel size of about 30 μm to 50 μm square, there is a problem that the pixel occupation area ratio is significantly reduced. Ta. That is, a reduction in the pixel occupation area results in the disadvantage that the display screen becomes darker as a whole and the display quality deteriorates.

(d) Means for Solving the Problems The method for manufacturing a TPT array of an active matrix display device of the present invention is to form a plurality of gate wirings made of opaque metal on a transparent substrate, and to insulate the transparent gates. After the films are laminated, a transparent conductive film is formed, and with a resist applied to the upper surface of the transparent conductive film, a resist forming an inverted pattern of the gate wiring is left by back exposure using the gate wiring as a mask. Using the remaining resist as a mask, a patterning process is performed to separate the transparent conductive film along the gate wiring, and then a resist is applied again, and an exposure process is performed to leave the resist at areas other than the drain wiring position, and the remaining resist is masked. By performing a patterning process to separate the transparent conductive film along the drain wiring, a large number of display electrodes made of the transparent conductive film in picture units are obtained.

(E) Function According to the method for manufacturing a TPT array of an active matrix display device of the present invention, the etching resist of the semiconductor film and the etching resist of the transparent conductive film are self-aligned to the gate wiring including the gate electrode using back exposure. Therefore, the semiconductor film is formed on the gate electrode and the transparent conductive film is formed offset from the gate wiring with high precision.

Embodiment FIG. 1 shows a plan view of a pixel unit of a TPT array of an active matrix display device obtained by the manufacturing method of the present invention.

A method for manufacturing the TPT array shown in FIG. 1 will be described below with reference to manufacturing process diagrams shown in FIGS. 2(i) to (partial) along line B-B.

(1) First step in Figure (i) A gate line 20 locally provided with a gate electrode portion 2 made of Cr, Ta, etc. is formed on a transparent substrate 1 made of glass using a photomask. Form into the shape of.

A plurality of gate lines 20 are formed so as to extend horizontally between pixels, and the gate electrode portion 2 of each gate line 20 is arranged at a TPT configuration position for each image processing. Note that by anodizing the surface of the gate line 20, it is possible to avoid a gate short-circuit accident.

(2) In the second step of the same figure (ii), the gate insulating film 3 made of a silicon nitride film or silicon oxide film, the amorphous silicon semiconductor film S4, and the phosphorus-doped amorphous silicon impurity semiconductor film S5 are P-C.
Films are sequentially formed using a VD device or the like.

(3), 3rd step of the same figure (ii) Applying a positive resist and exposing the gate electrode part 2 by back exposure.
The resist other than the gate line 20 position is exposed to light, and then the resist is exposed to normal light again from the front side using a 7-oto mask to leave the resist R1 in an island shape on the gate electrode portion 2. The semiconductor film S4 and the impurity semiconductor film S5 are patterned using the remaining resist (residual resist) R1 as a mask to obtain a TPT semiconductor film 4 and an impurity semiconductor film S5' laminated thereon in the same pattern.

(4), 4th step in the same figure (iv) After forming a transparent conductive film made of ITO on the entire surface by a method such as sputtering and applying a negative resist, the gate line with the gate electrode part 2 is formed by back exposure. A resist R2 having a reverse pattern of 20 is formed, and the transparent conductive film is patterned. Note that the above-mentioned reversal pattern formation can also be produced by an image reversal method using a positive resist.

As a result, the transparent conductive film has multiple gate lines 20...
- It is divided into a plurality of transparent conductive films C6 extending horizontally in a band shape with a width slightly narrower than the interval.

(5) The fifth step resist shown in FIG. By patterning C6, . . ., a large number of display electrodes 6, 6, . . . for each unit pixel are formed. Display electrode 6.6 at this time...
To form ., as shown in the same figure, etching is performed so that over-etching of 1 μm occurs.

(6) In the 6th step of the same figure (vi), a second metal such as titanium or aluminum is formed by a method such as sputtering, a resist is applied, and this is further exposed using a photomask to remove the remaining resist. By patterning the second metal using R4 as a mask, source electrodes 7, 7, .
, and a plurality of drain lines 80 including drain electrodes 8 bonded onto the impurity semiconductor film S5'.
...obtain... In this way, it is preferable to obtain channel dimensional accuracy by simultaneously patterning and forming the picture electrodes 7.8 on the impurity semiconductor film S5'.

(7) In the seventh step of the same figure (vii), the impurity semiconductor film S5' in the channel part of each TPT exposed as a result of the sixth step is removed by etching, and the drain electrode part 8 with respect to the semiconductor film 4 is removed. Also, an impurity semiconductor film 5 that realizes ohmic contact with the source electrode 7
．． form 5.

However, this impurity semiconductor film 5.5 is not necessarily necessary, and even if the semiconductor film 4 and the picture electrode 7.8 are directly bonded, TPT
The impurity semiconductor film 5.5 may be omitted if a junction state that does not impede the switching operation can be obtained. In this case, it becomes unnecessary to form the impurity semiconductor film S5 in the second step described above.

Through the steps of the method according to the embodiment of the present invention described above, the number of 7-otomasks used is reduced and the occurrence of pattern position shift due to the use of photomasks is suppressed, so that as shown in the plan view of FIG. , each display electrode 6... is shown in FIG. 6(a).
A TPT array of an active matrix display device that is enlarged with higher precision can be created using the conventional display electrode 6 shown in the plan view.

Furthermore, the steps of another embodiment of the method of the present invention are shown in FIG.

Figures (i) and (vii) are the same as Figure 2 (ii) above, respectively.
, (vii) corresponds to the steps of the embodiment of the present invention, and the other steps of this embodiment are similar to the other steps shown in FIG. 2, so their description will be omitted here.

FIG. 3(i) shows the second step. First, a gate insulating film 3 made of a silicon nitride film or a silicon oxide film is formed.
, amorphous silicon semiconductor films S4 are sequentially formed using a P-CVD apparatus or the like.

Subsequently, the TP on the gate electrode part z is removed using a photomask.
A channel protection insulating film 10 is patterned into a predetermined shape at the T channel position. As for the patterning method at this time, it is preferable to etch a resist formed by back exposure and front exposure using a 7-oto mask into a mask, as in the third step described above.

Thereafter, an impurity semiconductor film S5 is formed using a P-CVD device or the like. For example, a silicon nitride film or a silicon oxide film can be used as the channel protection insulating film IO.

FIG. 3(vii) shows the seventh step, in which the impurity semiconductor film S5' in the channel portion of each TPT is removed.
When removing the semiconductor film 4 by etching, the channel protection insulating film 10 is prevented from being etched to the channel portion of the semiconductor film 4.

As described above, by employing the manufacturing method of the present invention, for example, even when manufacturing an ultra-high definition liquid crystal display device compatible with high-definition with high image processing integration, the display electrodes 6...
By enlarging the pixel area, the pixel occupation area ratio increases.
A bright, high-quality display is possible on the display screen. Further, the present invention is not limited to liquid crystal display devices, and even if it is applied to EL or EC display devices, the manufacturing effect will be the same.

(G) Effects of the Invention The method for manufacturing a TPT array of an active matrix display device of the present invention uses a self-alignment method using back exposure for patterning a semiconductor film and a transparent conductive film,
Furthermore, since the drain wiring is formed by lift-off using the resist used for patterning the display electrodes, it is possible to reduce the number of 7-otomasks used, and as a result, it is not affected by photomask accuracy or alignment error, and in particular, the drain wirings are not affected by photomask accuracy or their alignment errors. This makes it possible to pattern display electrodes with extremely high precision. Therefore, according to the present invention, a high definition active matrix display device with a high aperture ratio can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view of each pixel of a TPT array of an active matrix display device obtained by the manufacturing method of the present invention, and FIGS. 2(i) to (vii) show the manufacturing process of the TPT array of FIG. 3(ii) and (vii) are process sectional views showing still another embodiment of the method of the present invention, and FIGS. 4(a) and (b) are process sectional views taken along line B. A plan view of each pixel of the array and its A-
A-line sectional view. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Gate electrode part, 3...
Gate insulating film, 4... Semiconductor film, 5... Impurity semiconductor film, 6... Display electrode, 7... Source electrode, 8...
・Drain electrode, 9... Additional capacitance electrode, 10... Channel protection insulating film, 20... Gate line, 80.
...Drain line. Figure 1

Claims (2)

[Claims] (1) Thin film transistors are arranged together with display electrodes at numerous intersections between a plurality of gate wirings and a plurality of drain wirings that intersect with the gate wirings, the gates of the thin film transistors are used as gate wirings, the drains are used as drain wirings, In addition, in a method for manufacturing a thin film transistor array for an active matrix display device in which a source is coupled to a display electrode, a plurality of gate wirings made of opaque metal are formed on a transparent substrate, and a transparent gate insulating film is laminated. After the formation, a transparent conductive film is formed, and with a resist applied to the upper surface of the transparent conductive film, a resist forming an inverted pattern of the gate wiring is left by back exposure using the gate wiring as a mask, and the remaining resist is removed. A patterning process is performed to separate the transparent conductive film along the gate wiring using a resist as a mask. Then, a resist is applied again, the resist is left in areas other than the drain wiring position through an exposure process, and the remaining resist is used as a mask to form a transparent conductive film. A method for manufacturing a thin film transistor array for an active matrix display device, characterized in that a large number of display electrodes made of transparent conductive films are obtained in pixel units by performing a patterning process that separates a conductive film along a drain wiring. (2) A first step of forming a plurality of gate wirings each including a gate electrode portion using a first metal on a light-transmitting substrate, a second step of forming a gate insulating film and a semiconductor film, and applying a resist to form a gate wiring. The resist at the gate wiring positions other than the gate wiring positions is exposed by exposure from the back side of the substrate using a plurality of gate wirings having electrode parts as a mask, and the resist at the gate wiring positions other than the gate electrode parts is exposed by exposure processing from the substrate surface. The third step is to leave an island-shaped resist on the gate electrode portion and pattern the semiconductor film using the resist as a mask. After forming the transparent conductive film, a resist is applied, and a plurality of gates with the gate electrode portion are formed. A fourth step in which a resist forming an inverted pattern of the gate wiring remains by exposure from the back side of the substrate using the wiring as a mask, and a patterning process is performed to separate the transparent conductive film along the gate wiring using the remaining resist as a mask. is coated and subjected to exposure processing to leave a resist corresponding to the positions other than the positions of the plurality of drain wirings comprising the drain electrode portion. Using the remaining resist as a mask, a patterning process is performed to separate the transparent conductive film along the drain wirings, and the pixel A fifth step is to obtain a large number of display electrodes made of a single unit of transparent conductive film, and a sixth step is to form a plurality of drain wirings each having a drain electrode portion and a large number of source electrodes in a predetermined shape using a second metal. A method for manufacturing a thin film transistor array for a matrix display device.