JPH0342626A - Production of thin-film diode - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display device having high display image grade by etching a 2nd metallic film and a semiconductor film by dry etching, then etching a 1st metallic film by wet etching. CONSTITUTION:After the 2nd metallic film 27 and the semiconductor film 29 are etched by the dry etching, the 1st metallic film 25 is etched by the wet etching. The overhang parts of the 2nd metallic film 27 on the semiconductor film 29 occurring in the differences in the film quality between the semiconductor film 29 and the 1st metallic film 25 as well as the 2nd metallic film 27 are, therefore, eliminated, by which the property to cover the step between an interlayer insulating film 39 and a conductive film 43 is improved and the generation of the disconnection of wirings 45 is prevented. The liquid crystal display device having the high display image quality is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an active matrix in a liquid crystal display device that drives a liquid crystal and displays an image by controlling switching elements provided in each of pixels arranged in a matrix. The present invention relates to a method for manufacturing an element.

[Conventional technology and its issues]

For example, Japanese Patent Application Laid-Open No. 62-262891 uses an amorphous silicon Luminium thin film diode as a switching element for driving a liquid crystal. As shown in FIG. 5, a plurality of row electrodes 15 and a pixel electrode are provided on one substrate, and a plurality of diodes 19 connected in antiparallel are connected between the pixel electrode and the row electrode 15. A plurality of column electrodes 17 are provided on the other substrate, and liquid crystal 21 is sealed between these two substrates.

The method for manufacturing a thin film diode described in the above publication is shown in FIG. Note that FIG. 6 shows a cross section of one diode.

First, as shown in FIG. 6(a), a transparent conductive film 16 is formed on the entire surface of the substrate 11, and the transparent conductive film 16 is patterned by photoetching to form row electrodes 15 and pixel electrodes 26.
to form. After that, a first metal film 25 made of chromium (Cr) having both light shielding properties and conductivity is formed on the entire surface,
A semiconductor film 29 and a second metal film 27 made of chromium
and sequentially form the sul. This semiconductor film 29 is made of amorphous silicon and has a pin conductivity type. The first metal film 25 and the second metal film 27 are arranged so that when the semiconductor film 29 is irradiated with light, a leakage current flows through the pin junction of the semiconductor film 29, and the diode does not function as a switching element, causing the display to be displayed. Provided as a light shielding film to prevent image quality from deteriorating. Thereafter, a photosensitive resin is formed on the entire surface and patterned by photolithography to form a patterned photosensitive resin 66 on the second metal film 27.

Next, as shown in FIG. 6(b), the second metal film 27, semiconductor film 29, and first metal film 25 are sequentially etched by dry etching using the photosensitive resin 66 as an etching mask. In this dry etching of the second metal film 27, the semiconductor film 29, and the first metal film 25, due to the difference in film quality between the semiconductor film 29, the first metal film 25, and the second metal film 27, The semiconductor film 29 has a pattern dimension smaller than that of the first metal film 25 and the second metal film 27, with a large difference in etching speed between the semiconductor films 29 and 29.
is formed.

Next, as shown in FIG. 6(C), an interlayer insulating film 69 is formed over the entire surface.
form. In forming this interlayer insulating film 69, since the second metal film 27 is formed in an overhanging manner with respect to the semiconductor film 29, the step coverage of the interlayer insulating film 69 is deteriorated. Therefore, the transparent conductive film 16 and the first metal film 2
The interlayer insulating film 69 is not formed in the stepped portion formed by the semiconductor film 29, the semiconductor film 29, and the second metal film 27.

Next, as shown in FIG. 6(d), a connection hole 41 is formed in the interlayer insulating film 69 by photoetching. After that, a conductive film 46 is formed on the entire surface, and the conductive film 46 is etched by photo-etching.
The wiring 45 is formed by patterning. This conductive film 4
6, the step difference in the conductive film 46 is also caused by the fact that the second metal film 27 is formed in an overhanging manner with respect to the semiconductor film 29 described using FIG. Coverage becomes poor. Therefore, there is a problem that the wiring 45 connecting the second metal film 27 and the pixel electrode 26 is disconnected.

It is an object of the present invention to provide a method for manufacturing a thin film diode that solves the above problems and does not cause disconnection of wiring.

[Means to solve the problem]

In order to achieve the above object, the thin film diode of the present invention is manufactured by the manufacturing process described below.

(a) A transparent conductive film is formed on the entire surface of the substrate, a first photoresist is formed on the transparent conductive film, and the transparent conductive film is etched using the first photoresist as a mask to form row electrodes and pixel electrodes. a step of sequentially forming a first metal film, a semiconductor film, and a second metal film on the entire surface and forming a second photoresist on the second metal film;
The second metal film and the semiconductor film are etched by dry etching using the photoresist as a mask, and the first metal film is etched by wet etching to simultaneously etch the second metal film. a step of etching the metal film to form a second metal film having a pattern dimension smaller than the semiconductor film pattern dimension; a step of forming an interlayer insulating film on the entire surface and forming a third photoresist on the interlayer insulating film; A step of etching the interlayer insulating film using the photoresist in step 3 as a mask to form a connection hole, forming a conductive film over the entire surface, and forming a fourth photoresist on this conductive film; and etching the film to form wiring.

(b) A transparent conductive film is formed on the entire surface of the substrate, a first resist is formed on the transparent conductive film, and the transparent conductive film is etched using the first resist as a mask to form row electrodes and pixel electrodes. a step of sequentially forming a first metal film, a semiconductor film, and a second metal film on the entire surface and forming a second resist on the second metal film; and a step of forming a second resist on the second metal film; A step of etching the second metal film and the semiconductor film using a mask by dry etching, and a step of etching the first metal film by wet etching to form a first metal film having a side etched portion.
a step of forming a second metal film and simultaneously etching the second metal film to form a second metal film having a pattern size smaller than the semiconductor film pattern size; forming a conductive film on the entire surface and etching the second metal film on the conductive film; Step 3 of forming a resist, etching the conductive film using the third resist as a mask to form wiring, and removing the second metal film and semiconductor film in the opening of the third resist. have

〔Example〕

The present invention will be described in detail below using the drawings.

FIGS. 1(a) to (g) are cross-sectional views showing the manufacturing method of a thin film diode according to a first embodiment of the present invention in order of steps, and FIG. 2 is a plan view showing the thin film diode of the present invention. Note that FIG. 1 shows a cross section of A-man in FIG. 2. This will be explained below with reference to FIGS. 1 and 2.

First, as shown in FIG. 1(a), a transparent conductive film 16 of, for example, indium tin oxide (ITO) is formed on the entire surface of a substrate 11 made of transparent glass to a thickness of 5Q nm to 200 nm. This transparent conductive film 16 is formed by a vacuum evaporation method or a sputtering method. Thereafter, a photosensitive material is formed on the entire surface, exposed to light using a photomask, and developed to form a first photoresist 61. The planar shape of the first photoresist 61 is indicated by a two-dot chain line 56 in FIG. Thereafter, using the first photoresist 61 as an etching mask, the transparent conductive film 16 is etched with a mixed solution of ferric chloride and hydrochloric acid.
A row electrode 15 consisting of 6 and a pixel electrode 26 are formed. After that, the first photoresist 61 is removed.

Next, as shown in FIG. 1(b) K, a first metal film 25 of molybdenum (MO) having a thickness of about 1QQ nm is formed on the entire surface by sputtering or vacuum evaporation. Thereafter, a semiconductor film 29 made of hydrogenated amorphous silicon (a-8i:H) is formed on the entire surface of the first metal film 25 by plasma chemical vapor deposition. The semiconductor film 29 is the first
It has a diode structure in which the conductivity types are p-type, i-type, that is, an intrinsic semiconductor containing almost no impurities, and n-type conductivity from the metal film 25 side. The thickness of each layer is 10 nm for the p-type layer.
The thickness of the J-type layer is 100 nm to 1.0 μm, and the thickness of the N-type layer is 10 nm to 100 nm. Thereafter, a molybdenum film having a thickness of about 1100 nm is formed as a second metal film 27 on the entire surface by vacuum evaporation or sputtering. After that, a photosensitive material is formed on the entire surface, exposed and developed, and the second
A photoresist 66 is formed. The planar pattern shape of this second photoresist 66 is indicated by a broken line 49 in FIG.

Next, as shown in FIG.
is used as an etching mask, and the second metal film 27 and the semiconductor film 2 are etched by anisotropic ion etching using, for example, a reactive ion etching device as dry etching.
Etch 9.

As the etching gas in the dry etching, a mixed gas of carbon tetrafluoride (CF4) to which 10% oxygen (02) is added is used. The degree of vacuum inside the reactive ion etching apparatus at this time was approximately 8 Pascals (pa).
High frequency power 0.3W/crL~0.4W/crj, etching gas 60 SCCM (standard C
ubiCCentimeters per m1nut
Supply at the flow rate of e). In the dry etching of the second metal film 27 and the semiconductor film 29, the etching speed differs due to the difference in film quality between the two, and as shown in FIG. A semiconductor film 29 having small pattern dimensions is formed.

Next, as shown in FIG. 1(d), the first metal film 25 is coated with phosphoric acid (H3r'o, ):acetic acid (CH8COOH):
Etching is performed by wet etching using an etching solution having a composition ratio of nitric acid (HNO3)=10:30:1. In the wet etching gas for the first metal film 25, the side surfaces of the second metal film 27, which is made of the same material as the first metal film 25, are also etched at the same time. For this reason, the first
The overhang portion of the second metal film 270, which was formed in an overhang shape with respect to the semiconductor film 29 as explained using FIG. A second metal film 2 having
7 is formed. After that, the second photoresist 66 is removed.

Next, as shown in FIG. 1(e), an interlayer insulating film 69 is formed over the entire surface.
A silicon nitride film (S
i x Ny ) is formed by plasma chemical vapor deposition. Thereafter, a photosensitive material is formed on the entire surface, and a third photoresist 65 is formed by exposing and developing using a photomask. The planar pattern shape of this third photoresist 65 is indicated by a solid line 47 in FIG.

Next, as shown in FIG. 1(f), a third photoresist 6 is applied.
5 as an etching mask, the interlayer insulating film 69 is etched by dry etching or wet etching to form a connection hole 41.

Thereafter, the third photoresist 65 is removed, and a molybdenum film 46 with a thickness of 03 μm to 2.0 μm is formed on the entire surface by sputtering.

Thereafter, a photosensitive material is formed on the gold stripes, exposed to light, and developed to form a fourth photoresist 67. The planar pattern shape of this fourth photoresist) 57(') is shown by the dashed-dotted line 51 in FIG.

Next, as shown in FIG. 1(g), a fourth photoresist 6 is applied.
7 as an etching mask, the conductive film 46 is etched using, for example, a reactive ion etching device as dry etching to form the wiring 45 a. The etching gas used in dry etching is a mixed gas of carbon tetrafluoride and oxygen. Note that the thin film diode is formed in the shaded area in FIG. Then a fourth photoresist 67
is removed, and the element-forming substrate is completed. The liquid crystal display device is
After applying liquid crystal alignment treatment to both the element formation substrate and the counter substrate using a general method, and bonding the two substrates together, liquid crystal is sealed, and the polarization axis is added to the outside of the liquid crystal cell thus formed. Complete by placing a polarizing plate in a twisted shape.

In the method of manufacturing a thin film diode of the present invention, after the second metal film 27 and the semiconductor film 29 are etched by dry etching, the first metal film 25 is etched by wet etching. Therefore, the semiconductor film 29 and the first metal film 25
The overhang of the second metal film 270 with respect to the semiconductor film 29 due to the difference in film quality with the second metal film 27 is eliminated, the step coverage of the interlayer insulating film 69 and the conductive film 46 is improved, and the wiring 45 disconnection will not occur.

A second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIGS. 3(a) to 3(f) are cross-sectional views showing the manufacturing method of a thin film diode according to a second embodiment of the present invention in order of steps, and FIG. 4 is a plan view showing the thin film diode of the present invention. Note that FIG. 3 shows a BB cross section in FIG. 4.

First, as shown in FIG. 3(a), a transparent conductive film 16 of indium tin oxide is deposited on the entire surface of a substrate 11 made of transparent glass to a thickness of 5Q nm to 200 nm by vacuum evaporation or sputtering. do. After that, a photosensitive material is formed on the entire surface, and a first resist 55 is formed by exposing and developing using a photomask. The planar pattern shape of this first resist 55 is indicated by a two-dot chain line 53 in FIG.

Thereafter, using the second resist 55 as an etching mask, the transparent conductive film 16 is etched with a mixed solution of ferric chloride and hydrochloric acid to form row electrodes 15 and pixel electrodes 26 made of the transparent conductive film 16. After that, the first resist 55 is removed.

Next, as shown in FIG. 3(b), a first metal film 2 is applied over the entire surface.
5, molybdenum with a film thickness of about 00 nm is formed by sputtering or vacuum evaporation.

Thereafter, hydrogenated amorphous silicon is formed as a semiconductor film 29 on the entire surface of the first metal film 25 by plasma chemical vapor deposition. The semiconductor film 29 has a diode structure in which the conductivity types from the first metal film 25 side are p type, I type, that is, an intrinsic semiconductor containing almost no impurities, and n type. The thickness of the p-type layer is l
Qnm~1100n, i-type layer 03μm~10μm1
n-type layer], On m~1. Let it be OOn m. Thereafter, molybdenum is formed as a second metal film 27 on the entire surface of the semiconductor film 29 to a thickness of about ]-0Q nm by sputtering or vacuum evaporation. Thereafter, a photosensitive material is formed all over, and exposed and developed to form a second lucist 57. The planar pattern shape of this second resist 57 is indicated by a broken line 49 in FIG.

Next, as shown in FIG. 3C, using the second resist 57 as an etching mask, the second metal film 27 is etched by anisotropic ion etching using, for example, a reactive ion etching device as dry etching. and the semiconductor film 29 are etched. A mixed gas of carbon tetrafluoride and oxygen is used as the etching gas in the dry etching. In the dry etching of the second metal film 27 and the semiconductor film 29, the etching speed is different due to the difference in film quality between the two, so as shown in FIG. 3(C), the second metal film 27 is formed in an overhanging manner with respect to the semiconductor film 29.

Next, as shown in FIG. 3(d), the first metal film 25 is etched by wet etching to form the first metal film 25 having side etched portions 61.

As a method for forming the side etched portion 61 in the first metal film 25, the side etched portion 61 can be formed by continuing etching from the just etching process in which the etching of the first metal film 25 has been completed. This first
The side etching amount of the side etched portion 61 of the metal film 25 is 0.51 μm to 10 μm. The side etching amount of the side etched portion 61 is controlled by the etching time from the above-mentioned just etching. In this wet etching step of the first metal film 25, the first metal film 2
The side cylinder of the second metal film 270, which is made of the same material as 5, is also etched at the same time. Therefore, the overhang portion of the first metal film 25 formed in an overhang shape with respect to the semiconductor film 29 is etched away, as explained using FIG. A second metal film 27 having dimensions is formed. After that, the second resist 57 is removed.

Next, as shown in FIG. 3(e), a conductive film 43 of molybdenum is sputtered over the entire surface to a thickness of 0.3 μm.
m to 2.0 μm. Thereafter, a photosensitive material is formed on the entire surface, exposed to light, and developed to form a third resist 59. Since the side etched portion 61 is formed on the side surface of the first metal film 25, a space corresponding to this side etched portion 61FC is generated between the conductive film 46 and the first metal film 25, and the conductive film 46 and the first metal film 25 are not short-circuited.

Next, as shown in FIG. 1(f), using the third resist 59 as an etching mask, the conductive film 46 is etched by dry etching or wet etching to form a wiring 45. Furthermore, using the third resist 59 as an etching mask, the area not covered by the third resist 59, that is, the second metal film 27 and the semiconductor film 29 in the opening of the third resist 59, is etched with tetrafluoride. Etching is performed using a reactive ion etching device using a mixed gas of carbon and oxygen as an etching gas.

Note that the thin film diode element is formed in the shaded area in FIG. As shown in FIG.
It has a two-layer structure of 3 and a conductive film 46, reducing wiring resistance.

In the thin film diode manufacturing method explained using FIGS. 3 and 4, it is possible to manufacture the thin film diode using three photomasks. Furthermore, after dry etching the second metal film 27 and the semiconductor film 29, the first
The metal film 25 is etched by wet etching.

Therefore, the overlapping portion of the second metal film 270 relative to the semiconductor film 29 is etched away during the wet etching of the first metal film 25. Therefore, the step coverage of the conductive film 46 is improved, and disconnection of the wiring 45 does not occur.

In the above explanation, the first metal film 25 and the second metal film 27 are made of molybdenum, but materials other than molybdenum may be used as long as they have both light-shielding properties and conductivity. can. Furthermore, although the first metal film 25 and the second metal film 27 are made of the same material, it is not necessary to use the same material, and the first metal film 25 and the second metal film 27 can be etched using an etching solution in wet etching. Second metal film 2
The first metal film 25 and the second metal film 27 may be made of materials that can be etched at the same time. Furthermore, the first metal film 25 and the second metal film 27 are made of different materials, and after the first metal film 25 is etched by wet etching, the second metal film 27 is formed on the first metal film 2.
The second metal film 27 is removed from the semiconductor film 29 by wet etching using an etching solution different from the etching solution in step 5.
The overhang portion may be removed by etching.

The conductivity type of the semiconductor film 29 is p from the first metal film 25 side.
Although the example has been explained in which a type layer, a type 1 layer, and an n-type layer are laminated, a laminated film of an n-type layer, a type 1 layer, and a p-type layer from the first metal film 25 side may also be used. An n-type layer and a p-type layer are formed from the metal film 25 side.
It may be a type layer or a laminated film of a p-type layer and an n-type layer.

Although an example in which molybdenum is used as the conductive film 46 has been described, a high melting point metal film, a high melting point metal silicide film, or a metal film is also applicable.

Furthermore, the interlayer insulating film 69 includes not only a silicon nitride film but also a silicon oxide film (SiOX), a silicon oxynitride film (SiON), etc.
), an aluminum oxide film (A i 203), and other insulating films can be used.

〔Effect of the invention〕

As is clear from the above description, in the method for manufacturing a thin film diode of the present invention, after the second metal film and semiconductor film are etched by dry etching, the first metal film is etched by wet etching.

Therefore, the overhang portion of the second metal film with respect to the semiconductor film due to the difference in film quality between the semiconductor film, the first metal film, and the second metal film is etched away, and the step coverage of the conductive film is improved. , there will be no disconnection of wiring.

Therefore, a liquid crystal display device with high display image quality can be obtained.

Conventionally, the second metal film, semiconductor film, and first metal film were all etched by dry etching. For this reason, it has been impossible to form a transparent insulating film, such as a silicon oxide film, on the surface of the glass substrate under the transparent conductive film in order to suppress the elution of alkali ions from the glass substrate. This is because, in dry etching, the surface of the transparent insulating film is etched by etching ions and the transmittance of the transparent insulating film deteriorates, making it impossible to form a transparent insulating film on the surface of the substrate. On the other hand, in the thin film diode manufacturing method of the present invention, the first metal film is etched by wet etching, so the etching solution for the first metal film can be etched by 1'! The transparent insulating film formed on the substrate surface is not etched, and a transparent conductive film can be formed on the substrate surface. Therefore, it is possible to suppress the elution of alkali ions from the substrate with a transparent insulating film formed on the substrate surface, and prevent the electrical resistance from becoming small due to the alkali ions in the liquid crystal material, thereby preventing display defects in the liquid crystal display device. The occurrence can be completely suppressed.

4. Brief explanation of the figures Figures 1 (a) to (g) are simplified diagrams showing the manufacturing method of a thin film diode in the first embodiment of the present invention in the order of steps;
The figure is a plan view showing a thin film diode according to the present invention.
Figures (a) to (f) are cross-sectional views showing the method for manufacturing a thin film diode according to the second embodiment of the present invention, without showing the process order;
Also, FIG. 5 is a plan view showing the thin film diode of the present invention, FIG. 5 is a circuit diagram showing thin film diodes connected in antiparallel, and FIGS. 6 (a) to (d) are cross sections showing a conventional thin film diode manufacturing method in order of steps. It is a diagram.

25...First metal film, 27...Second
metal film, 29...semiconductor film, 46...
- Conductive film, 45... wiring, 61... side etched portion.

Game 1 1st rI1 9 semiconductor film Figure 2 15° 3 electrodes 41° "Skill" hole Figure 3 Figure 3 29, semiconductor layer 45, Wiring 61, Su4 Doe, Sochi Department Figure 4 23, Box 1 series Denrei 15, row electrode 17, train electric micro 19, 9” i4-de

Claims (2)

[Claims] (1) A transparent conductive film is formed on the entire surface of the substrate, a first photoresist is formed on the transparent conductive film, and the transparent conductive film is etched using the first photoresist as a mask to form row electrodes and pixel electrodes. a step of sequentially forming a first metal film, a semiconductor film, and a second metal film on the entire surface and forming a second photoresist on the second metal film; and a step of forming a second photoresist on the second metal film; etching the second metal film and the semiconductor film by dry etching using the mask as a mask;
etching the metal film by wet etching, etching the second metal film at the same time as etching the first metal film, and forming the second metal film having a pattern dimension smaller than the semiconductor film pattern dimension. forming an interlayer insulating film over the entire surface and forming a third photoresist on the interlayer insulating film; etching the interlayer insulating film using the third photoresist as a mask to form connection holes; A thin film diode comprising the steps of forming a conductive film and forming a fourth photoresist on the conductive film, and etching the conductive film using the fourth photoresist as a mask to form wiring. Production method. (2) A transparent conductive film is formed on the entire surface of the substrate, a first resist is formed on the transparent conductive film, and the transparent conductive film is etched using the first resist as a mask to form row electrodes and pixel electrodes. a step of sequentially forming a first metal film, a semiconductor film, and a second metal film on the entire surface and forming a second resist on the second metal film; and a step of forming a second resist on the second metal film; etching the second metal film and the semiconductor film using a mask by dry etching, and etching the first metal film by wet etching to form the first metal film having a side etched portion; etching the second metal film to form the second metal film having a pattern size smaller than the semiconductor film pattern size; forming a conductive film on the entire surface and forming a third resist on the conductive film; and a step of etching the conductive film using the third resist as a mask to form a wiring, and further removing the second metal film and the semiconductor film in the third resist opening. A method for manufacturing a thin film diode characterized by: