JP2846681B2 - Method of manufacturing thin-film transistor array for active matrix display device - Google Patents

Description

The present invention relates to a method for manufacturing a thin film transistor array of an active matrix display device.

(B) Conventional technology In recent years, an active matrix display device has been developed in which a thin film transistor (hereinafter, referred to as a TFT) that functions as a switching transistor is coupled to each of a large number of display electrodes in a matrix arranged in a matrix, and the TFT is used as a drive circuit. ing. This device supplies pixel information to each display electrode via a TFT, and applies an electric field, current, or power according to the pixel information to a liquid crystal layer, an EL layer, or the like provided on the display electrode.
An optical change is given to the EC layer to enable a visible display [Japanese Patent Publication No. Sho 62-6674].

In particular, an active matrix type liquid crystal display device using the above-described liquid crystal layer has recently attracted attention as a pocketable TV display.

FIG. 5 (a) is a plan view of a pixel unit of a TFT array in a conventional active matrix type liquid crystal display device.
FIG. 4B is a sectional view taken along line AA of the TFT position.

These TFTs in the same figure correspond to one insulating substrate 1 of the liquid crystal cell.
An ohmic contact is formed on each of the gate electrode 2 formed above and 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. Constituent impurity semiconductor film
5, 5, a so-called inverted staggered type comprising a laminate of a source electrode 7 and a drain electrode 8, and a display electrode 6 for each pixel is coupled to the source electrode 7.

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

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

(2) A step of sequentially forming a gate insulating film 3, a non-single-crystal semiconductor film 4, and a non-single-crystal impurity semiconductor film 5 using a P-CVD apparatus or the like.

(3). A step of etching the semiconductor film 4 and the impurity semiconductor film 5 using a photomask and a photoresist.

(4). A step of forming a transparent conductive film and forming the display electrode 6 using a photomask and a photoresist.

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

(6). A step of etching the impurity semiconductor film 5 at a channel position between the electrodes 7 and 8;

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

Generally, pitch error of current photomask is ± 1μ
m, since the alignment error of the exposure apparatus is ± 1 μm, according to the above-described conventional manufacturing method, a pattern position shift of ± 2 μm, that is, 0 to 4 μm occurs. Design needed. For this reason, when a display device such as an ultra-high-definition liquid crystal display device compatible with high-definition, for example, a high-pixel integrated pixel having a pixel size of about 30 μm to 50 μm square is manufactured, there is a disadvantage that the pixel occupation area ratio is significantly reduced. Was. That is,
Decreasing the pixel occupied area leads to a defect that the display screen is darkened as a whole and the display quality is reduced.

(D) Means for Solving the Problems A method of manufacturing a TFFT for an active matrix display device according to the present invention comprises forming a plurality of gate wirings made of an opaque metal on a light-transmitting substrate, and forming a light-transmitting gate insulating film. After laminating, a light-transmitting conductive film is formed, and a resist is applied to the upper surface of the transparent conductive film, and the 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 for separating the transparent conductive film along the gate wiring is performed, and then, a resist is applied again, and an exposure process is performed to remove a portion other than the position of the drain wiring and the source electrode provided with the drain electrode portion. By performing a patterning process of leaving the resist and separating the transparent conductive film along the drain wiring using the remaining resist as a mask, a pixel unit is formed. A large number of display electrodes made of a transparent conductive film are obtained, and then, a resist is formed so that the display electrodes are exposed by performing an exposure process for further expanding the opening at the source electrode position of the remaining resist to the display electrode side. A metal is deposited on the entire surface, and a drain wiring having a drain electrode portion and a source electrode are formed by lift-off.

(E) Function According to the method for manufacturing a TFT 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 with the gate wiring having the gate electrode by back exposure. Therefore, the semiconductor film is formed on the gate electrode with high accuracy, and the transparent conductive film is formed on the gate wiring with high accuracy in an offset state. Furthermore, since the drain wiring provided with the drain electrode portion and the source electrode wiring are lift-off formed by using a transparent conductive film etching resist that is further exposed, that is, by etching and lift-off using substantially the same resist. Since each pattern is formed, a highly accurate display electrode, a drain wiring, and a source electrode wiring made of the transparent electrode can be obtained without being affected by the photomask and the exposure apparatus.

(F) Embodiment FIG. 1 is a plan view of a TFT array of an active matrix display device obtained by the manufacturing method of the present invention in pixel units.

The method of manufacturing the TFT array of FIG. 1 will be described below with reference to the manufacturing process diagrams of FIGS. 2 (i) to 2 (viii) along the line BB.

(1). (I) First step A gate line in which a gate electrode portion 2 made of Cr or Ta is locally provided on a transparent substrate 1 made of glass.
20 is formed in a predetermined shape using a photomask. A plurality of the gate lines 20 are formed so as to extend between pixels in the horizontal direction, and the gate electrode portion 2 of each gate line 20 is provided for each pixel.
It is located at the TFT configuration position. Incidentally, by anodizing the surface of the gate line 20, a gate short circuit accident can be avoided.

(2). (I) Second step The gate insulating film 3 made of a silicon nitride film or a silicon oxide film, the amorphous silicon semiconductor film S4, and the phosphorus-doped amorphous silicon impurity semiconductor film S5 are subjected to P-CVD.
Films are sequentially formed using an apparatus or the like.

(3). (Iii) Third step: A positive resist is applied, the resist other than the position of the gate line 20 provided with the gate electrode portion 2 is exposed by back exposure, and then the resist is again exposed from the front side using a photomask. Normal exposure is performed, the resist R1 is left in an island shape on the gate electrode portion 2, and the semiconductor S4 and the impurity semiconductor S5 are patterned using the remaining resist R1 as a mask,
Obtaining an impurity semiconductor film S5 ¹ were laminated in the same pattern as the semiconductor film 4 of the TFT thereto.

(4). (Iv) 4th step A transparent conductive film made of ITO is formed on the entire surface by a method such as sputtering, a negative resist is applied, and the reverse pattern of the gate line 20 provided with the gate electrode portion 2 is exposed by back exposure. Is formed, and the transparent conductive film is patterned. The above-described reverse pattern can also be formed by an image reversal method using a positive resist.

As a result, the transparent conductive film is divided into a plurality of transparent conductive films C6 extending laterally in a strip shape with a width slightly smaller than the interval between the plurality of gate lines 20.

(5). A resist is applied by applying a resist, and a resist R3 having a reverse pattern of a plurality of drain lines 80 provided with the drain electrodes 8 and the source electrodes 7 is formed by a photomask. Each transparent conductive film C6 divided into a plurality in the horizontal direction in four steps ...
Are further divided in the vertical direction to form a large number of display electrodes 6 for each unit pixel.
At this time, the display electrodes 6, 6,... Are etched so that over-etching of about 1 μm occurs, as shown in FIG.

The resist R remaining on the TFT channel determines the channel length when the lift-off of the drain electrode 8 and the source electrode 7 is performed later.

(6). (Vi) Sixth step The resist remaining in the fifth step is subjected to a second exposure process to remove a part of the resist R3 of the inversion pattern for the many source electrodes 7 to partially expose the display electrode. obtaining a residual resist R3 ¹ being.

Since the exposure process when this is to extend the opening of the resist R3 ¹ corresponding to the source electrode 7 to the display electrode 6 side, already displayed do not change the channel length defined in the fifth step electrode Exposure is performed only on the edge portion on the 6th side.

(7). It is left a resist R3 ¹ in the seventh step the sixth step of FIG. (Vii), was formed by a method such as sputtering the second metal such as titanium and aluminum in this state, the drain electrode by the resist R3 ¹ 8 ...
Are formed by lift-off. Therefore, the drain line
80 ... by overetching of the fifth step, the adjacent display electrodes 6, 6 ... are separated by a narrow gap of about 1μm and a drain electrode 8 ... some impurity semiconductor film S5 ¹ of
Join on top. And further both S5 ^1, 6 joined together in other portions display electrodes 6 ... upper part of the source electrode 7 ... are joined on the impurity semiconductor film S5 ¹ are wired coupling.

(8). The impurity semiconductor film S5 ¹ of the channel portion of each TFT that results exposed eighth step the seventh step of FIG. (Viii) is removed by etching, the drain electrode 8 against the semiconductor film 4, and the source electrode 7
Impurity semiconductor film 5, which realizes ohmic contact of
5 is formed.

However, the impurity semiconductor films 5 and 5 are not always necessary, and even if the semiconductor film 4 and the two electrodes 7 and 8 are directly
The impurity semiconductor films 5 and 5 may be omitted as long as a junction state that does not hinder the switching operation can be obtained. In this case, the formation of the impurity semiconductor film S5 in the above-described second step is unnecessary.

In the steps up to the eighth step, the structure of each wiring, TFT and display electrode can be obtained. Further, the manufacturing steps of the additional capacitance electrode 9 shown in FIG. An additional description will be given with reference to the drawings.

In the additional capacitance electrode 9, the source electrode 7 and the drain electrode 8 are simultaneously lifted off in the sixth and seventh steps of FIG. That is, as shown in FIG. 3 (vi), a part of the display electrode 6 and the adjacent gate line
A resist R3 ¹ was attached to the opening 20 position. continue,
In the seventh step, as shown in FIG. 7 (vii), an island-shaped additional capacitance electrode 9 overlapping a part of the adjacent gate line 20 via the gate insulating film 3 is obtained by lift-off of the second metal.

The additional capacitance electrodes 9 are connected to the respective display electrodes 6 as described above.
It is formed every time, and increases the charge storage capacity of each display electrode 6 by the capacity between the adjacent gate line 20 and contributes to the suppression of the potential decrease of the display electrode 6 due to power consumption.

As a method of providing such an additional capacitor, a method of providing an additional capacitor counter electrode having an independent counter potential in addition to the above-described method using the adjacent gate electrode as a counter electrode is conceivable. When this method is adopted in the present invention, at the time of the above-mentioned first step, an additional capacitance line having an additional capacitance counter electrode made of the first metal is formed so as to extend in parallel with the gate wiring at the same time as the gate wiring. It should be noted that the additional capacitance electrode 9 may be arranged not on the adjacent gate line 20 but on the additional capacitance counter electrode in the sixth and seventh parts.

By the steps of the method of the embodiment of the present invention described above, the number of photomasks to be used is reduced, and the occurrence of the shift of the pattern position due to the use of the photomask is suppressed, as shown in the plan view of FIG. The TFT array of the active matrix display device in which each display electrode 6 is enlarged with higher accuracy than the conventional display electrode 6 in the plan view of FIG.

FIG. 4 shows the steps of another embodiment of the method of the present invention. Figures (ii) and (viii) correspond to Figure 2 (ii),
This corresponds to the step (viii) of the embodiment of the present invention, and the other steps in this embodiment are the same as the other steps in FIG.

FIG. 4 (ii) shows a second step. First, a gate insulating film 3 made of a silicon nitride film or a silicon oxide film and an amorphous silicon semiconductor film S4 are sequentially formed using a P-CVD apparatus or the like. Subsequently, the channel protection insulating film 10 is patterned into a predetermined shape at a TFT channel position on the gate electrode portion 2 using a photomask. As a patterning method at this time, as in the third step described above, it is preferable to perform etching using a resist formed by back exposure and surface exposure using a photomask as a mask.

After that, the impurity semiconductor film S5 is formed by a P-CVD device or the like. As the channel protection insulating film 10, for example, a silicon nitride film or a silicon oxide film can be used.

Figure 4 (viii) shows an eighth step, in this step, the impurity semiconductor film S5 ¹ channel portion of each TFT when etched away, the channel protective insulating film
10 is prevented from being etched to the channel portion of the semiconductor film 4.

As described above, by adopting 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 pixel integration, the pixel occupancy is increased by forming the display electrodes 6. Since the area ratio increases, a high-quality display with a bright display screen can be performed. Further, the present invention is not limited to a liquid crystal display device, and the same manufacturing effect can be obtained even when the present invention is applied to an EL or EC display device.

(G) Effect of the Invention The method for manufacturing a TFT array of an active matrix display device of the present invention uses a self-alignment method using backside exposure for patterning a semiconductor film and patterning a transparent conductive film.
In addition, since the drain wiring is formed by lift-off using the resist used for patterning the display electrode, the number of photomasks used can be reduced, and thus the photomask is not affected by photomask accuracy or its alignment error. Very high-precision patterning can be performed on the display electrode and the drain wiring. In addition, the source electrode can also be lifted off at the same time as the drain electrode provided on the drain wiring, and the resist exposure that determines the distance between the two electrodes can be realized with a single mask, so that the dimensional accuracy of the channel length does not deteriorate. It is possible to manufacture a highly reliable TFT having no variation in characteristics.

Therefore, according to the present invention, a high-definition active matrix display device with stable display quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view in pixel units of a TFT array of an active matrix display device obtained by the manufacturing method of the present invention,
2 (i) to 2 (viii) are cross-sectional views showing the manufacturing process of the TFT array of FIG. 1 along the line BB, and FIG.
i) and (vii) are cross-sectional views showing the steps of the additional capacitance electrode 9 shown in FIG. 1 along the line CC of FIG. 1, and FIG. 4 is a process cross-section showing still another embodiment of the method of the present invention. Figure, FIG. 5 (a)
And (b) are a plan view in pixel units of a conventional TFT array and a cross-sectional view taken along line AA. DESCRIPTION OF SYMBOLS 1 ... Translucent board, 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 protective insulating film, 20
…… Gate line, 80 …… Drain line.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/336 H01L 29/786 G02F 1/136 500 G02F 1/1343

Claims (3)

(57) [Claims] 1. A thin film transistor is arranged together with a display electrode at a number of intersections between a plurality of gate wirings and a plurality of drain wirings intersecting the gate wiring, and the gate of the thin film transistor is a gate wiring, and the drain is a drain wiring. In a method of manufacturing a thin film transistor array of an active matrix display device in which a source is coupled to a display electrode, a plurality of gate wirings made of an opaque metal are formed on a light transmitting substrate, and a light transmitting gate insulating film is laminated. After formation, a transparent conductive film is formed, and in a state where a resist is 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 Using the resist as a mask, a patterning process is performed to separate the transparent conductive film along the gate wiring. A pixel is formed by applying and exposing a resist remaining at positions other than the drain wiring and source electrode positions provided with the drain electrode portion, and separating the transparent conductive film along the drain wiring using the remaining resist as a mask. A large number of display electrodes made of a unit transparent conductive film were obtained, and thereafter, a resist in which the display electrodes were exposed was formed by performing an exposure process for further expanding the opening at the source electrode position of the remaining resist to the display electrode side. A method of manufacturing a thin film transistor array for an active matrix display device, comprising: depositing a metal on the entire surface in a state, and forming a drain wiring and a source electrode provided with a drain electrode portion by lift-off. 2. A first step of forming a plurality of gate wirings having a gate electrode portion on a light-transmitting substrate with a first metal, a second step of forming a gate insulating film and a semiconductor film, and applying a resist. A plurality of gate wirings each including a gate electrode portion are used as a mask to expose a resist other than the gate wiring portion by exposure from the rear surface of the substrate, and a resist at a gate wiring position other than the gate electrode portion is exposed by exposure processing from the substrate surface. A third step of patterning the semiconductor film using the resist as a mask, forming a transparent conductive film, applying a resist, and forming a plurality of gate electrodes with the gate electrode part. Exposure from the back surface of the substrate using the gate wiring as a mask leaves a resist forming an inverted pattern of the gate wiring, and the remaining resist serves as a transparent conductive mask. A fourth step of performing a patterning process of separating the film along the gate wiring, applying a resist, and performing a first exposure process to form a resist having an inverted pattern for a plurality of drain wirings including a drain electrode portion and a number of source electrodes; A fifth step of performing a patterning process of allowing the remaining resist to separate the transparent conductive film along the drain wiring using the remaining resist as a mask to obtain a large number of display electrodes made of the transparent conductive film in pixel units; By the second exposure process
A sixth step of further removing a part of the resist of the inversion pattern for a large number of source electrodes to obtain a residual resist partially exposing the display electrode, depositing a second metal, and forming a residual resist obtained in the sixth step A method for manufacturing a thin-film transistor array of an active matrix display device, comprising: forming a drain wiring having a drain electrode portion and a source electrode by lift-off. 3. An island-shaped additional capacitance electrode made of a second metal, which is independent of a drain wiring having a drain electrode portion and a source electrode, is formed by lift-off, and a part of the additional capacitance electrode is connected to the display electrode. 2. The method according to claim 1, wherein the other portion is extended over the adjacent gate wiring.